© 2026 Zoe. All rights reserved.
Zoe is a legal information platform. Always consult the official source for authoritative text.
[2009] TASSC 109
Supreme Court of Tasmania
2009-12-11
Porter J
Original judgment source is linked above.
CITATION: Beswick v Tamarack Pty Ltd [2009] TASSC 109
HEARING DATES: 21 - 24 April, 28, 29 April, 6 May 2009
Torts - Negligence - Essentials of actions for negligence - Duty of care - As between employer and employee - Employed driver of log truck - Rollover of loaded truck on bend of highway - Alleged deficiencies in suspension and load measuring systems - Interference in suspension settings by fellow employee - Whether employer negligent - Whether employee contributorily negligent.
Evidence - General - Means of proof - Photographs - Whether substantive evidence - Interpretation of what is depicted.
Blacktown City Council v Hocking [2008] NSWCA 144; Warren v Gittoes [2009] NSWCA 24, followed.
Evidence - Opinion evidence - Expert opinion - In general - Admissibility - Opinion based on specialised knowledge - Admissibility distinguished from weight - Evidence Act 2001, s79.
Sydneywide Distributors Pty Ltd v Red Bull Australia Pty Ltd [2002] FCAFC 157, applied.
Judgment Number: [2009] TASSC 109
Heavy vehicle safety and truck rollovers [16] - [21]
•
Experience and training [22] - [27]
•
Negotiating the Plenty bends [28] - [30]
•
The system in general [31] - [47]
•
Adjusting the height control valves (HCV's) to increase the ride height [48] - [51]
•
Handling problems with the plaintiff's truck [52] - [59]
•
The fitting of high flow HCVs to the plaintiff's truck [60] - [65]
•
The evidence of the plaintiff and other employees [79] - [90]
•
The expert evidence [91]
•
Findings of fact [92]
•
The evidence [93] - [100]
•
Findings of fact [101] - [102]
The cause of the rollover - the expert opinions
•
The use of photographs [108] - [112]
•
Mr Lambert's opinion [113]
o Load weighing system [114] - [129]
o The suspension system, the HCVs and the raising of the ride height [130]
•
Dr McLean's opinion [131] - [140]
o The plaintiff's speed around the corner [141]
o An admissibility issue [142] - [166]
o Mr Lambert's response [167] - [168]
o Further aspects of Dr Prem's second report [169] - [180]
The causes of the rollover and whether the defendant was negligent
•
Discussion [181] - [186]
•
The suspension factors [187] - [189]
•
Uneven loading [190] - [192]
•
The plaintiff's speed [193] - [199]
1 The plaintiff, Harley Beswick, was a log truck driver. He was employed by Tamarack Pty Ltd, which I will simply call "the defendant". (The company has been de-registered; hence the presence of the Nominal Insurer as second defendant.) In September 1996, he was driving a semi-trailer combination, being a prime mover with a single trailer "log jinker" attached. Most of his work was carting logs to the paper mill at Boyer, using the Lyell Highway. On 27 September 1996 at about 11.40pm, he was at Plenty travelling south towards New Norfolk. On the last of a series of bends adjacent to the Derwent River - a left hand bend - his loaded truck rolled over, coming to rest against a tree on the river bank, at a point off to his right hand side of the roadway. (I use the term "rollover" loosely, because there is some debate about the extent to which the truck actually rolled over before it struck the tree.) The plaintiff was injured and has brought this action against his employer for damages. Those damages are agreed; liability is the issue.
2 The prime mover was a Kenworth model. It had a single steer axle with bogie (dual) drive axles. The drive axles were factory fitted with a Hendrickson WD2-460 air suspension system. The jinker was a tri-axle single stanchion trailer which could be longitudinally folded at about its centre point, in order to be piggybacked when not loaded. The tri-axle group was also equipped with an air suspension system. Fitted at intervals of about 3.5 metres from front to back along each side of the trailer, were four steel vertical posts, each about two metres high, referred to as bolsters. The sections created by the two sets of forward bolsters and the two sets of rear bolsters are known as "bunks". With this truck, the forward-most bunk was located at the very front of the trailer, putting it above and just behind the line of the front axle of the drive axles. The centre of this bunk was about 700mm behind the second drive axle. The rear-most bolster sat approximately above the back of the rear-most wheels of the trailer, with the next bolster about in line with the forward-most wheel of the tri-axle group. The centre of this bunk was about 150mm behind the second trailer axle. The practice was to load one pile of logs onto the front bunk, with a second pile of logs onto the rear bunk.
3 The fundamental issue is what caused the log truck to roll over. There is much to be considered in that exercise. Unfortunately, the action came on for trial nearly 13 years after the event. The writ was not issued until July 1999. No explanation for the delay became apparent during the hearing. It seemed to me that the delay did cause some difficulty in relation to what evidence was called, and the way in which it emerged. To a very large extent, the case between the parties was conducted as a contest between two expert engineers called by the plaintiff, and one called on behalf of the defendant, all of whom had impressive credentials in the field. The earliest of the expert reports is dated February 2006.
4 None of the experts were able to inspect the prime mover or trailer, or had the opportunity of visiting the scene within a reasonable time after the accident. Each attempted to interpret skid marks and other features shown in photographs of the scene which were apparently taken a few days after the accident. The person who took the photographs was not called. As to the opinion evidence in general, some of the factual assumptions made were not capable of easy identification, some were proved differently in the evidence than as assumed, and with no consequent revision; some were not proved at all. It is a matter to which I will return, but at the time of the accident, both parties seemed to have an erroneous view of the law as to permissible axle loads, and all experts proceeded on the basis of similar erroneous views.
5 The plaintiff alleges a lack of proper training in relation to driving the loaded log truck with its particular or potential characteristics. Further, based on expert evidence, the plaintiff's case is that the truck rollover commenced from the drive axles and was caused by:
•
the inherent characteristics of the airbag suspension system on the bogie drive axles of the prime mover, which gave rise to handling difficulties and general instability.
•
an exacerbation of that situation by the re-setting of the height of the suspension by a fellow employee on the shift before that of the plaintiff, of which the plaintiff was not made aware.
•
a load indicator system installed on the trailer which, when used in accordance with the defendant's instructions, resulted in the truck being overloaded, with a particular overload on the drive axles of the prime mover.
6 The defendant's case, based on its expert evidence, is that there was but one simple cause of the accident, and that was the plaintiff's excessive speed into and around the corner. The defendant claims that numerical and whole of vehicle animated modelling, along with some photographic evidence of the scene, demonstrates that the rollover commenced from the rear of the trailer. The defendant's argument as to speed, as pursued at trial, did not raise any response to the plaintiff's allegation that this resulted from an absence of proper training.
7 It is common ground that a speed advisory sign of 55km/h was erected just before the particular series of bends at Plenty. Depending on how the characterisation is done, there were either five or six bends in the series. The sign showed a vertical "wavy" line, rather than a single curve, and it seems to be accepted, and in any event I find, that the sign applied to all of the bends. The plaintiff accepts that he attempted to negotiate the last corner at about 70km/h. A printout from a built-in computer on the prime mover (the "Tripmaster" system) reveals a speed of 72km/h at a point in the corner.
8 The plaintiff alleges that the defendant was negligent in the following ways:
"(a) required and/or permitted and/or allowed the plaintiff to drive the truck which was unsuitable and/or dangerous by reason of the facts that:
(ii) the load weighed in excess of the safe load (the plaintiff relies on inference from all the evidence that the weight was excessive)
(b) failed to train the plaintiff in driving the truck, in particular that by reason of the suspension system and/or overloading and/or unevenly distributed load he should enter corners cautiously at a reduced speed and that the truck may become destabilised after successive corners.
(c) failed to install an accurate load indicating system on the truck such as a Lodec.
(d) fitted levelling valves to the suspension system were unsuitable and/or not in accordance with the manufacturer's specifications.
(e) allowed a course its employer, Michael Pearson, [sic Pearton] to interfere with the mechanism of the levelling valves of the suspension system.
(f) required the plaintiff to drive an inherently unstable truck."
9 The defendant alleges that the plaintiff, by his own negligence, caused or contributed to his injuries. The particulars of the negligence alleged are that the plaintiff:
(b) failed to keep his vehicle under any or any proper control.
(c) drove his vehicle at a speed which was excessive in the circumstances.
(d) failed to apply the brakes on his vehicle in time or at all to avoid the said collision.
(e) failed to steer or control his vehicle so as to avoid the said collision.
(f) failed to ensure that his load was evenly distributed before commencing his journey.
(g) failed to direct the loader operator to re-distribute his load in the event that it was unevenly distributed before commencing his journey.
(h) failed to ensure, whether by way of examination, inspection or inquiry, that:
(iii) the centre of gravity of his load was evenly balanced;
(i) drove his truck and load through successive corners at a speed in excess of the signposted advisory limit for all motor vehicles at 55km/h, namely 72km/h."
10 The resolution of the case requires the consideration of seven issues. Matters concerning the truck and the rollover itself, involve examining the expert evidence. The last two issues depend on findings of fact in relation to the earlier ones. The seven issues are:
•
the plaintiff's driving, - generally (including his training), and on the night of the accident;
•
the suspension of the prime mover and the fitting of high flow height control valves to that suspension at some time prior to the accident;
•
whether the ride height of the prime mover's suspension was altered by a fellow employee, Mr Pearton, on the day of the accident;
•
the air pressure load measuring system on the prime mover and trailer, and its effect on how the truck was loaded;
•
the weight and dimensions of the load on this particular occasion;
•
the cause of the rollover; and
•
the liability of the defendant for any of its acts or omissions which caused it, and whether the plaintiff was contributorily negligent.
11 Before dealing with the issues which I have set out, I need to explain a point as to the law which applied at the date of the plaintiff's accident. Maximum wheel and axle loads were then governed by the Traffic (Vehicle Loads and Dimensions) Regulations 1975. Relevantly, the regulations were as amended by Statutory Rule 1986 No 291. Given the axle configurations which I have earlier set out, the following were the applicable axle load limits:
•
6 tonnes on the steer axle - reg7(2)(a)(i).
•
14.3 or 15 tonnes on the drive axles - (depending on whether the air suspension fitted is properly described as a load sharing system or not) - reg7(3)(a)(i) or (ii).
•
17.7 or 20 tonnes on the trailer tri-axle group - (again depending on whether or not that system is properly described as a load sharing system) - reg7(5)(a)(i) or (ii).
12 In his evidence, the plaintiff said that he was instructed by the defendant to load the truck to the maximum legal limit, including "tolerances". The figures he gave were 23.5 tonnes on the truck and 21 tonnes on the trailer; a total of 44.5 tonnes. The tolerances were amounts of grace given by the transport authority. The tare weight of the prime mover and trailer combination was given as 14 tonnes. In cross-examination it was explained that the permitted gross combined mass ("GCM") was 42.5 tonnes, with the tolerances being one tonne for the prime mover and one tonne for the trailer, giving the total of 44.5 tonnes.
13 The first of the plaintiff's experts was Mr John Lambert. Three reports were tendered, the first dated February 2006, the second and third both dated February 2007. In his first written report, he says that the "legal limit" on the steer axle was 6 tonnes, with 16.5 tonnes on the drive axle group "plus part of the enforcement tolerance being 0.5 tonnes giving a total of 23 tonnes". He goes on to say that the "legal limit" on the tri-axle group was 20 tonnes "plus part of the enforcement tolerance being 0.5 tonnes giving a total of 20.5 tonnes"; a GCM of 43.5 tonnes. The second of the plaintiff's experts was Dr Arnold McLean. Two reports were tendered, the first dated 24 January 2008, the second 11 March 2008. The issue was not raised in either. However, in his oral evidence, when he was describing the air suspension system, he described the relevant legal axle loads as 6 tonnes, 17 tonnes and 21 tonnes for a single steer axle, dual drive axle and tri-axle trailer respectively; a GCM of 44 tonnes.
14 The defendant's expert engineer was Dr Hans Prem. In two written reports, one dated August 2006, the other dated July 2008 (both responding to the reports of Mr Lambert) he does not raise any issue as to Mr Lambert's assertions of the legal axle load limits. At the trial he seemed to assume that what Mr Lambert had said was correct. Dr Prem's opinion was based on a configuration of the vehicle in which "the vehicle is both correctly loaded, the axle group loads are at their legal maxima". The loaded weights given were 6 tonnes, 16 tonnes, and 20 tonnes. Accordingly, both parties (including their respective experts) conducted the trial on the basis that the legal axle load limits were the same as, or close to, the figures given by the plaintiff. However, as is apparent, those figures were not the legal axle load limits at the time, but are in accordance with amendments to the regulations effected by Statutory Rule 1996, No 129, which commenced on 1 October 1996, and coincided with the commencement date of the Traffic Amendment (National Road Transport Reform) Act 1996. This was of course only three days after the plaintiff's accident.
15 I made this discovery after judgment had been reserved. By memorandum, I raised this point, along with some incidental issues, with both parties. Neither sought leave to amend the pleadings nor was there any application to re-open. I have been told by way of written submissions that both the plaintiff and the defendant are content to let the evidence stand as it is. The plaintiff acknowledges that it is not part of his case that the defendant had in place a system which resulted, intentionally or otherwise, in continual overloading above the actual legal axle limits, and is "content to proceed on the basis that the plaintiff and the defendant each thought that the stated limits were the legal limits ...". The defendant notes the point as to the nature of the plaintiff's case, and adds that in any event, because of the state of the evidence about the suspension systems, it is not possible to make a finding as to what were the actual limits. All of this means that I am to proceed on the basis that both the plaintiff and the defendant were, at least, acting on a mistaken view of the legal limits, and that the experts, to varying degrees, made the same mistake. It is agreed that I have to approach the expert evidence on the basis that references to the "legal limit" (or similar) should be read as the "assumed legal limit". How all of this came about was not explained.
16 As a further preliminary matter, it may be of benefit to set out some general aspects of this subject-matter, which have been discussed in many papers and reports. The plaintiff tendered a number of these by consent, included in which were the following:
•
An Assessment of Heavy Truck Safety in Tasmania - John de Pont of Transport Engineering Research New Zealand Ltd ("TERNZ") - July 2005.
•
Report on Survey of Heavy Vehicle Rollover Stability in Tasmania - John de Pont - October 2006.
A paper of Dr Prem (and others) entitled Performance Characteristics of the Australian Heavy Vehicle Fleet - February 2002 - was also tendered by the plaintiff in Dr Prem's cross-examination.
17 Although these papers and reports post-dated the accident by quite a few years, it is quite plain that the issues which are discussed have relevance to the question of rollover stability of log trucks, including the type of combination driven by the plaintiff, as things stood in 1996. The TERNZ July 2005 report on heavy truck safety in Tasmania analyses crash data for heavy truck and truck combinations starting in 2002, but the report incorporates a discussion paper on New Zealand log transport safety which has statistics relating to log truck rollover crashes from 1999. The essential characteristics of the vehicles have by and large remained the same, and the relevant laws of physics have not been recently amended. Additionally, Dr Prem in his cross-examination, said that issues of rollover stability, including factors of speed, centre of gravity, and weight of load were well known in the logging industry in 1996.
18 In his first report, Mr Lambert identified the following factors as determining the limits of vehicle stability in rollover situations at a curve. There seems to be no controversy about the list.
•
The height of the centre of mass ("COM") of the vehicle; - the higher the COM, with all other factors constant, the less stable the vehicle.
•
The track width - (the width between the centres of the wheels or dual wheels at the end of each axle); - the wider the track with all other factors constant, the more stable the vehicle.
•
The stiffness of the tyres and the roll stiffness of each suspension; - the higher the roll stiffness, the less the vehicle leans and the more stable it is.
•
The characteristics of the load.
•
The vehicle's speed.
•
The inverse of radius of the curve the truck is following; - double the radius and the side force is halved.
•
The superelevation of the curve (the slope of the road pavement towards the inside of the curve); - the greater the superelevation, the less likely the vehicle is to rollover.
•
The dynamics of travel down the road.
19 A central concept relevant to these issues is what is known as static rollover threshold ("SRT"), which is a measure of rollover stability during steady speed cornering. I have based the following description on material which appears in the two reports of Mr de Pont referred to above. When a vehicle is driven through a curve, it experiences lateral acceleration. The magnitude of this acceleration depends on vehicle speed, curvature and cross-slope (or superelevation) of the curve. SRT is the maximum steady turning acceleration which the vehicle can withstand before the wheels on the inside of the curve lift off the ground. This is the beginning of rollover. SRT is expressed as a fraction of the unit of acceleration due to gravity, the symbol for which is "g". High values of SRT mean a better resistance to rollover. There is a time component involved, in that the force needs to be applied long enough to produce the effect. Research into crashes has demonstrated the obvious implied premise; that is, vehicles with low SRT values have a higher rollover rate than vehicles with high SRT values. Apparently, in 2007, the Australian National Transport Commission in its Performance Based Standards system of heavy vehicle regulation, adopted a minimum value of SRT at 0.35g as acceptable in relation to heavy vehicles.
20 The TERNZ July 2005 report noted that of the 60 large heavy vehicles included in the study which had a rollover crash, 72 per cent were semi-trailers, with the rollover crash rate for log trucks, woodchip trucks and stock trucks, significantly higher (2.5 times) than the rest of the heavy vehicle fleet. The author observed that poor rollover stability does not mean that a vehicle rollover is inevitable. "Within limits it is possible to drive a vehicle low rollover stability reasonably safely provided the driver adjusts the speed through curves accordingly, although there is a smaller safety margin available in emergency situations." The further TERNZ October 2006 report involved a study of 96 heavy vehicles, 15 of which were of the log jinker semi-trailer type. It was established that the average SRT for those 15 vehicles was 0.32. Accordingly, it was concluded that, "overwhelmingly, the vehicle category that currently does not achieve a 0.35 level of rollover stability is log trucks".
21 Dr Prem assessed the plaintiff's truck in a "correctly loaded" state as having at best, an SRT of 0.309. The situation of a vehicle in close proximity to rollover throughout a turn was addressed by Dr Prem in his report of 18 July 2008. Although his remarks were directed specifically to the plaintiff's truck, they are of general application. He said that for a vehicle in such close proximity, "it would take very little to precipitate rollover - an imprecise steer correction, a small change in speed, a small load shift, or a slightly different line through the turn and a sequencing of bumps in the road."
22 At the time of the accident the plaintiff was an experienced semi-trailer driver. He had worked continuously as a semi-trailer driver for 11 years prior to the accident, having driven heavy rigid trucks before then. He had exclusively driven log trucks since 1987, his employment with the defendant starting in 1992. For the whole of the period he was driving log trucks, he delivered logs to either Boyer or Triabunna. The plaintiff underwent an assessment by the Driver Education Centre of Australia in December 1993. This was required for his employment, and involved an evaluation of two trips on the same day. The plaintiff said that both loads were taken from the far Plenty Valley but that the journey did not involve negotiating the series of bends where the accident occurred. His evidence continued as follows:
"Did it involve going past a speed advisory sign?........Yes.
And what was the speed on that sign?........Sixty five.
Right, and did you take that bend at your usual speed on that day?........Yes.
On both loads?........Yes.
And at what speed did you take it?........Approximately ninety.
Mm, and did the instructor say anything to you about your speed on that bend?........No.
Did he say anything to you about your speed on any bend?........No."
In the DECA driver evaluation report, the instructor gave the plaintiff an "A" for his "speed for environment" on both days of the two day assessment. By ticking a box the instructor endorsed the comment that the plaintiff "has an excellent attitude and is very keen to learn. Applies all he/she has learnt during the course and is considered a good and safe driver". The instructor's handwritten comments are that "Harly [sic] is good to work with and had a good attitude toward training..."
23 The plaintiff described John Vanderwal as the principal of the defendant company, with Rob Reynolds, the transport manager, as his immediate supervisor. Michael Cox was Mr Reynold's assistant and was employed as "driver evaluator". The plaintiff described one incident of Mr Cox travelling with him at some stage before his accident. He said that there was no advanced warning of the evaluation. They travelled together in the truck from the defendant's yard at New Norfolk to Tarraleah, through the Plenty bends, and back the same way with a load of logs to Boyer. The plaintiff said that they passed numerous speed advisory signs, including the 55km/h one at the Plenty bends, and said that he did not drive any differently in terms of his speed or of the line that he took on the roadway to any other day. (He said later in his evidence that he usually drove past the speed advisory sign and into the first of the Plenty bends at 70km/h). The plaintiff said that Mr Cox did not say anything to him about his speed, and said that given the configuration of the truck cab, Mr Cox was able to see the speedometer from where he was sitting in the passenger seat.
24 The plaintiff described the operation of the "Tripmaster" system on the truck. Each driver was issued with a plastic ID card about the size of an ordinary credit card. That was put into a slot in the dashboard of the prime mover cabin and was left there for the whole shift. At the end of the shift, the truck would be taken to a diesel bowser where there was a computer connection which was plugged into a USB port or similar, in the cabin, and the information recorded by the system was downloaded to the office computer. The plaintiff said that "_they could look at whatever you did in the truck, the gear changes, speed, revs, engine brake usage - _ ".
25 A "Tamarack Transport - Company Standards" document is in evidence. Amongst other things set out in that document are "The Professional Drivers Ten Commandments", two of which are as follows:
•
"When on the road, observe all state laws and respect the laws of nature to do with forces, momentum, and the centre of gravity of your vehicle."
•
"Don't hesitate to slacken your speed and be ready to stop the instant potential danger appears."
The plaintiff was asked whether he was able to comply with the requirements of the document, or whether he had any difficulty with it. He said that his attitude to it was fine and that he had no problem with it.
26 The plaintiff said that he was under no time pressure in the job. He was asked about his practice in relation to speed advisory signs. I have already noted the situation in relation to the 55km/h sign at the Plenty bends. He was asked questions about other speed advisory signs between the Plenty bends and the Boyer paper mill. By reference to signs shown in photographs, the plaintiff said that he travelled at 70km/h around a bend marked 45km/h, 90km/h around one marked 65km/h, 90km/h around one marked 55km/h. In relation to the final photograph identified, he said that he travelled at 90km/h around a bend marked 85km/h but the reason for that was that it was close to a descent into the town of Bridgewater where there was a 60km/h speed limit sign. His explanation was that he was familiar with the roads and how the truck travelled on that road.
27 Evidence was given of the plaintiff's driving habits by Malcolm McGregor. Mr McGregor worked for the defendant for about 12 years up until 1998 when he retired. He said that he often travelled in convoy with the plaintiff; over the years probably between 60 and 100 times. He said that the plaintiff knew most of the roads "like the back of his hand" and was able to guide him as to what lay ahead. As to his observations of the plaintiff's driving in general, he said:
"Well I would say Harley was one of the best drivers I ever knew. It's all he ever done. I've never seen him recklessly cut corners or on the wrong side of the road, he always kept - was on his own side of the road. All drivers - when you can see a long way ahead you try and straighten the corners out as much as you can without going into the other lane, but I would say Harley his driving was very confident, he wasn't a reckless driver, he was always on his own side of the road and never saw him have any near misses or anything like that." [Emphasis added]
28 The plaintiff said that the defendant operated about 18 trucks in 1996 with around the clock operations; two drivers being allocated for each truck, each driver doing a 12 hour shift. On the day of the accident the plaintiff was carting logs from Tarraleah which was a regular place of origin. In a 12 hour shift he would be able to do three return trips. In his nine or ten years of log truck driving, about 70 per cent of trips had involved negotiating the Plenty bends. The plaintiff said that his driving through the Plenty bends, his speed, selected gear and line taken, were consistent from one occasion to the next. He was taken through the way in which he had normally negotiated the bends prior to the accident. Travelling in a southerly direction, he said that the first bend was a right handed bend. There was "a little left kink" before that bend, which he said, was "hardly really noticed". In the plaintiff's case, the right hand bend was accordingly called the first bend. However, Dr Prem counted this bend as the second corner, and as his numbering ultimately became predominant in the trial, I will use his system. The first right hand bend is therefore bend 2. The plaintiff said that he travelled around that bend at 60km/h. He said that he maintained "roughly about 60, because the exit of that bend where it actually straightens out is the worst part of it, because the road elevates then it - the camber of the road goes the opposite way, so the weight of the vehicle becomes unsettled on that particular part of the road".
29 From the exit of that bend, the plaintiff said that he gradually increased the speed through the rest of the bends and stayed in the same gear. The next bend is a left hand turn, immediately after which is a right hand turn, at which point he said he would be travelling at about 65km/h. What follows is the first of two left hand bends. He said that approaching the first of these two left hand bends, he "lifted off" the throttle so that the drive was "sort of in a neutral zone, ... you haven't got that momentum through but you're still carrying the speed but you're not actually creating momentum ...". He said that this was because the camber of the road changed. It went from assisting the vehicle through the right hand bend to assisting the vehicle through the left hand bend. Approaching the sixth and last of the bends (bend 6) - another left hand bend - he said he maintained the same gear and held the speed. He said it was an "excellent" curve to negotiate. "The vehicle flows through the curve well balanced, there's nothing unsettling in that curve, and the camber of the road assists the vehicle through there, it travels through nicely balanced."
30 The plaintiff was asked about his line through these various corners and said that through each corner the truck was maintained within its lane, and whilst on occasions the right hand wheels would be close to the centre line, it was not necessary to cross over to negotiate any of the bends. Similarly, he said on occasions the left side wheels would be close to the white fog line marked on the left side of the carriageway, but that it was not necessary to cross over that line. In cross-examination, the plaintiff was not challenged on this evidence, nor asked about it all. As will become apparent, the issue has significance in the defendant's case.
31 The essential feature of the suspension system is that instead of mechanical springs, it has airbags. On a suspension for a bogie axle configuration there are two airbags on each side, each located immediately behind the axle mounts on the trailing arms. I set out below a sketch taken from the manufacturer's specifications. As fitted, the front of the truck is to the left of the diagram. The attachment point for the axles are on the arms to the left of the upright springs, which are to the left of the airbags.
32 The airbags are inflated by compressed air sourced from a compressor on the prime mover itself. Each time the rear trailing arms move up or down, a height control valve (one per set of airbags) is activated, moving air into or expelling it from, the airbags. If, for example the vehicle leans to the right, the height control valves will cause the right side airbags to expand, and the left side airbags to deflate, thus "levelling" the prime mover. At least as the manufacturer claims, the height control valves are for "increased roll control". A ride height is pre-set according to the manufacturer's specifications. This ride height can be adjusted. Mr Lambert in his first report described the type of suspension as having "medium roll stiffness". He says that such a suspension system requires the height control valve ("HCV") on each side of the suspension to keep the vehicle upright; "Otherwise the compliant rubber bushes would allow the prime mover to lean to one side or the other in travel. The lean would result from the road camber and/or the fact that the load was slightly off-centre".
33 Mr Lambert says that in Australia, two-lane two-way roads are mostly built with a high crown in the centre to effect water drainage. In that context, he describes the operation of the suspension system as follows:
"[I]n normal travel the vehicle will lean to the left, and the airbag on the left hand side will be compressed and that on the RHS will extend. The HCV on the left will interpret the compression as indicating the height of the axle is too low and so will pressurise the LHS airbag until the height difference is corrected. And the HCV on the right will interpret the extension as indicating the height of the axle is too high and so will exhaust the RHS airbag until the height difference is corrected ... [W]ith twin HCV airbag suspension systems the variation in airbag pressure is much greater than the +- 5% - 10% variation expected. The question is where are the extra airbag forces resisted. Basically the extra forces act to distort the suspension. The trailing arms and their connections to the axle form a large roll resistance bar. The trailing arm of the suspension is forced down on the LHS and the RH arm moves upward. ... [T]he RHS of the axle moves up and backwards and LHS [sic] end of the axle moves down and forwards. The axle is now not aligned correctly with the chassis and so wants to steer the vehicle to the right. ... As the drive axles will want to steer the combination to the right the driver will need to steer to the left ... But that will tend to cause the vehicle to curve to the left. So in time he will have to steer more to the right. This process may require the driver to undertake continuous steering corrections.
Consequential effects of uneven side - to - side airbag pressure. The rate of transfer of air into and out of the airbags is slowed because the tubes leading into and out of the airbags are small. Hence if the airbags on the left hand side have become pressurised, and those on the right have been partially discharged, in a situation where a vehicle starts to lean to the right the high pressure in LHS airbags will cause the trailing arm on that side to be forced up while the low pressure on the RHS will allow that trailing arm to drop down. This will tend to increase the likelihood of the prime mover rolling over to the right."
34 The plaintiff tendered the manufacturer's specifications. However, these are dated April 2000. They state: "To achieve exceptional roll control with improved air system response times a High Flow Height Control Valve (HF-HCV) may be fitted. When using two High Flow Height Control Valves, the need for a high volume to supply the air is increased". I would here interpolate Mr Lambert's evidence that the WD2-460 was withdrawn from the market, (I infer sometime in or after 2000), and replaced with a different version in 2003.
35 In cross-examination, Mr Lambert was not able to offer a flow rate in explanation of his comment that the rate of transfer of air into and out of the airbags was slow. He answered the question by saying that he had conducted a test on the same suspension showing a time taken of 13 seconds for the airbag pressures to equalise on the two drive axles. There was a 10 centimetre lift of one axle. Mr Lambert disagreed that the height control valves had any function to perform in terms of roll control. He said that the valves were not there to assist roll control but to make sure that as the load on the truck was altered, the height was not altered so that "the steering angles and all the other aspects - of alignment aspect of the vehicle are maintained". He said that they were not there to work in travel, but unfortunately many manufacturers positioned the valves in places which made them work in travel, which was not their purpose.
36 Mr Lambert continued: "[N]ormal height control valves that are fitted have a dead band in the middle where movement of the suspension up and down does not result with any air flow moving into or out of the airbags, but where there are trucks with problem suspensions and as this one - in other words, trucks that wander and dart and are difficult to drive - one of the solutions or part of the solution is ... to put high flow, high response height control valves and on some vehicles that improved the way they performed. But the height control valve is not designed to install as part of the suspension to actually act dynamically in travel ...".
37 Mr Lambert accepted that the manufacturer represented that the height control valves were for increased roll control, but maintained that the valves were primarily to set the height of the suspension as loads were put on and off. Mr Lambert explained his point as follows:
"The flow is so low that it doesn't have any meaningful effect on [the suspension and the stability of the vehicle]. Because the time it takes for air to move round is so slow in relation to - if a truck goes over a 50mm bump at 100 kilometres an hour, a second later it's 30 metres down the road. It's passed the bump. In that time there's virtually no - there can't be any meaningful airflow from one airbag to another in that time."
38 Dr McLean, in his first report, referred to the general deficiencies of heavy vehicle, (particularly prime mover), air suspensions as including:
"• The air spring pressure varies significantly over time dependent on the actual instantaneous suspension displacement, instantaneous loads and system response to previous in-service events.
•
The air suspension roll, resistance and spring stiffness varies very significantly over time.
•
The suspension characteristics including vehicle dynamic rollover threshold characteristics are strongly non-linear.
•
The suspension and hence vehicle and steering handling characteristics are strongly payload extent and centre of gravity location dependent.
•
The suspension characteristics differ significantly from those in mechanical systems which are stable and consistent.
•
Heavy vehicles installed with air suspensions on both the prime mover and trailer exhibit particularly adverse handling behaviour."
39 In his second report, Dr Mclean says that the WD2-460 exhibits a high sensitivity to low centre of gravity, and significant roll steer. He identified a number of other design deficiencies of this suspension, amongst which were that the pivoted trailing suspension arms were excessively stiff in comparison to the flexible prime mover chassis, and the system utilised twin ride height control valves - one set per side located remote from the bogie centreline. Additionally, Dr McLean says that the WD2-460 suspension "has application to slow (ie less than 80km/h) heavy, high tare, relatively rigid chassis, essentially off road vehicles".
40 In the report, the first identified "general deficiency" was further explained as it specifically related to the plaintiff's vehicle negotiating the corner at which the accident occurred. Dr McLean noted that the cornering would have caused the vehicle, "particularly and initially the prime mover", to lean to the offside. This would have caused the near side height control to have vented. He goes on to say:
"It must noted the cornering lean and load transfer action is instantaneous. Whereas the air spring venting action is strongly prime dependent. Due to the aforementioned different actions excessive pressures occurred in the near side air springs. The excessive pressure in the near side air springs generates a catapulting action. This catapulting action is enhanced by the fact exhaust from the furthest connected air spring is slower due to the systems exhaust flow resistant characteristics. The same is further exacerbated by the offside ride height control valve opening to counteract the depressed offside ride height. During this valve operation the pressure differential across the offside ride height valve is adverse. Consequently adverse backflow may occur. This catapulting action would have been exacerbated by the rapid change in the road camber up to and immediately after the corner's apex and the suspension and chassis flex in response to the same".
41 In his evidence, this first identified deficiency was explored. Dr McLean explained that "actual instantaneous suspension displacement" means that when a vehicle rolls, sufficient resistance air pressure in the airbags has to develop to resist the roll effect, so it instantaneously increases. He continued:
"But if a truck goes through a long sweeping corner, ... the rolling action causes the ride heights control valve to make the truck become more level. So that fluid flow is a time dependent variable and it takes times for that actual levelling to occur."
This, Dr McLean said, keeps the pressure the same, but when the vehicle exits the corner there is excess pressure, "so you have this integrated effect of pressure which is the system response to previous in-service events".
42 Dr McLean went on to explain another factor which caused increase and decrease in the air spring pressures and which affect the roll stability. This was the third identified general deficiency; that of "strongly non-linear suspension characteristics". He described a phenomenon known as "torque rise" or "frame rise" which was the combination of two forces created by the application of power to the drive wheels. Drive torque applied to the drive axles lifts up the frame or chassis of the prime mover in a vertical rearward action. This upward movement causes a decrease in airbag pressure. At the same time, because of the revolutions of the drive line, the torque applied results in high pressure in the airbags (with this truck) on the right hand side. If power is applied, the roll stability on the drive axles is actually reduced, as well as the roll effect of the truck being assisted. Dr McLean described all of this as "a very complex phenomena" with air suspensions on drive axles being vastly different to mechanical suspension.
43 In his first report, Dr McLean said that he understood the plaintiff's truck had negotiated a succession of corners prior to the rollover, which succession had generated "a magnitude accumulation of pressure deviations and approach through and exiting of the corners". In his evidence he explained this as follows:
"Well as a vehicle in the sequence of corners lead into the subject corner there's a major long - generally long sweeping right hand bend and the vehicle would've leaned to the near side, or to the left, and that would've caused instantaneous increase in pressure on the air bags on the near side, on the drive, and the effect is that because it's a long sweeping bend that the levelling valve's tried to correct it and through flow is a time phenomena and will take time to do it. In a short sequence of bends the air bags don't have enough time to get the truck to stand up perpendicular to the road and so it's a time phenomena, so on a big long sweeping bend, which is the first bend into this sequence of curves, at and about the 55 advisory speed sign there that is termed the long sweeping curve. And also we have the problem that the - if the driver backs off and - the truck speed will suddenly decrease because of rolling resistance, so the fact that he's maintaining constant speed or increasing speed slightly indicates that power is going down the drive line so these air springs are actually subject to the frame rise effect becoming like marshmallows, they're actually pressuring these air springs, they're decreasing, so it's a very highly non-linear complex phenomena, subject to this levelling effect on a long sweeping bend."
44 It will be recalled that Dr McLean in his first report said that the catapulting action he described would have been exacerbated by the rapid change in the road camber up to and immediately after the corner's apex and suspension of chassis flex. In evidence, he was asked to explain that. He said that due to the fact the vehicle had completed a major sweeping right hand bend, it was expected that the pressure in the left hand side airbags was excessive and "even though the vehicle is travelling light on the bogey because of this disturbance due to this torque being applied to the drive line that the pressures were higher still on the new side and that gets the left hand chassis rail and kicks it up and transfers the load to an increased amount to the steer tyre" [sic].
45 He went on to elaborate on an additional factor which related to his complaint that the WD2-460 had trailing suspension arms were excessively stiff. In the suspension setup, the trailing arm was fixed to the chassis at its forward-most point. To the rear of that point there is a point on the arm at which the axle is attached, with the airbag being at the rear-most point of the trailing arm. These three points were described as the pivot point, the load point, and the point of effort. As I understand it, Dr McLean's premise was that the pressure in the airbag could reach a stage at which, because of the stiffness of the trailing arm, the axle connection point formed the pivot, with the load being taken up by the airbag. The end result of that was "... very large forces going to the pivot point. It elevates the chassis rail."
46 In cross-examination Dr McLean said that his evidence as to the characteristics of air suspension systems was based on involvement in a study on vehicles operating with air suspension systems which was initiated by the Federal Office of Road Safety in approximately September 1998. This was a major investigation, a number of vehicles involved in which were equipped with the WD2-460 suspensions. He said he studied those very closely as to why they were causing problems. He agreed that airbag suspension systems were generally still in use, but that some manufacturers, including Hendrickson, since about 2000 have used flexible trailing arms to mitigate the effects of the rigid arms.
47 Dr Prem did not specifically address the features of the suspension in his two reports, but the issue was taken up with him in his evidence-in-chief. He referred to the two height control valves, one on the left and one on the right, those valves being "... designed to keep the suspension arm, if you like, in the same position relative to the chassis. So, it's designed to reduce the amount that the axle rotates relative to the chassis and that's rotation in roll." He agreed that that is what the phrase "roll control" meant and went on to say that the high flow height control valves were seen as an improvement to the previous version of those valves, and that Hendrickson now have an even higher flow version.
Adjusting the HCVs to increase the ride height
48 In his first report, Mr Lambert noted the suggestion that someone had adjusted the HCVs to raise the ride height of the suspension "in the belief that it would make the suspension more rigid and hence more stable". He thought that this might have been done on the assumption that forcing more air into the airbags would increase the pressure in them and make them stiffer. Mr Lambert detailed a number of actual effects of carrying out this exercise. It raises the COM at the drive axles and makes the vehicle less stable. The COM will increase by roughly the amount of the rise in suspension height. The pressure in the airbags actually remains about the same, but the height of the airbag will increase and alter its characteristics. Using a graph and assuming a height increase of 70mm, he purported to illustrate that "the changed airbag height results in a softer spring - that is a lower spring rate. Hence for any circumstance where there is a variation in vertical loads on the changed airbag it will deflect further." As a result of the lower spring rate, the HCV will be open for longer, so variations in airbag pressure will increase, and the problems he had previously described in relation to airbag suspensions generally would worsen.
49 He said that it was possible that if the height of the airbag was increased too much, then the limits to the extension of the shock absorber may be reached. As a result, the suspension would be much stiffer, and in fact for much of the time it would act as though it were rigid. However, based on the description of the vehicle performance at the time, he said that this seems not to have been the case. The description of the vehicle performance he was given is not revealed. The plaintiff's evidence about the behaviour of the truck on the accident was not put to him. He said that in summary "altering the HCV to significantly alter the height setting has many detrimental effects on vehicle handling and stability. As a result this could have significantly reduced the vehicle's stability". (Although in his opening address, the plaintiff's counsel went through the process in some technical detail of how the suspension height might be adjusted, all that is in evidence is the WD2-460 "Technical Bulletin", in which there is direction as to how, in very simple practical terms, to effect an adjustment to the ride height.)
50 In cross-examination, Mr Lambert accepted that the ride height was intended by the manufacturer to be adjustable but "within a very narrow range for each vehicle ...". The WD2-460 Technical Bulletin provides that "a given ride height must be obtained" as shown in a table. For Kenworth, the minimum and maximum ride heights are shown as 430mm and 440mm. It is not clear whether this is the minimum and maximum physically achievable, or whether as Mr Lambert's evidence might suggest, it was the manufacturer's intended, or recommended settings.
51 In his second report, Dr McLean said that he understood that prior to the accident the ride height had been increased by approximately 38mm "by adjusting the lengths of the feedback linkage between the feedback take off connection and the ride height control valve input arms". No source of this information is revealed, and again, the plaintiff's evidence was not put to him. He went on to say that a 38mm change in the ride height would have severely altered the vital drive line geometry and power transmission efficiency. He continued:
"By increasing the ride height the centre of gravity of the load is higher. In general the lower the centre of gravity the more stable the truck and its load. Accordingly increasing the centre of gravity by approximately 38mm will increase both the static and dynamic rollover risk. Further it will also increase the ... height (to the top of the turntable coupler plate between the truck and trailer). This would also reduce the static and dynamic rollover stability of the truck and its load.
Both the adjustment of the ride height and the use of the WD2-460 suspension system would have given a driver false feedback concerning the stability and weight of the load being carried at the time.
With the increase in ride height the suspension would have become 'stiffer' at the bogie. This would give the driver feedback on a straight level section of road of increased stability."
52 The plaintiff said that he commenced to drive the Kenworth prime mover in the middle of May 1996. Before that he drove a Freightliner prime mover. He said that this truck was consistent in its road behaviour and feedback, explaining feedback to mean "the feeling of the vehicle as you travel along, you get a feeling of the vehicle, how it behaves, how it's cornering, and you drive within the limitations of the vehicle". There was no need to make continual steering adjustments with this truck, nor did it wander nor veer at all. He was asked as to whether he noticed anything different about driving the Kenworth as distinct from the Freightliner. He replied that he had to continually apply steering input which he did not have to do with the Freightliner. The evidence continued as follows:
"And why was it that you had to continually put, have steering input?.............Um, the truck appeared to veer from side to side in the lane carriageway. So, I'd have to steer - if it veered right I'd have to steer to the left and vice versa to keep the truck under control.
Did you find any problem with the rear of the vehicle?.............Um, yes.
And what was that?.............Oh, the rear of the vehicle would lift up while it was in motion or either lift up as a whole or lift up one side or the other left or right.
HIS HONOUR: Sorry, when you say vehicle do you mean the entirety, truck and trailer?
WITNESS: The, no, the -
HIS HONOUR: Or just the prime mover?
WITNESS: The prime mover, the drive wheels of the prime mover.
MR READ (resuming): Did you find anything unusual about the way it cornered?.............Yes.
And what was that?.............It could do that in a corner or on a straight piece of road and that would require an input from the driver.
Right, now were these problems predictable. In other words you'd know when they were going to happen, happen according to a particular time or place?.............No.
Can you just enlarge on that answer?.............Um, they was predictable as in I expected it, um, be ready for it to happen, um, but exactly - you could say exactly where it was going to do it, you couldn't.
Now, did those problems change at all in the three months that you drove your vehicle up to the time of the accident?.............Yes.
Mm, can you enlarge on that please?.............The night of the accident it didn't give any veering or wandering characteristics.
All right, now back to when the problems were there, did you attribute the problems to anything?.............I, yes.
Mm, and what was that?.............Um attributed it to the overloading on the drive."
53 He was asked whether he spoke to anyone at Tamarack in relation to these problems. He said that he first spoke to Rob Reynolds and John Granville - (Mr Granville's role was identified in the evidence). He said that he told them that the truck would veer from side to side and he would have to continually correct the steering to keep the truck in the direction of intended travel, and that he believed it to be dangerous. On one occasion he spoke directly to Mr Vanderwal, notwithstanding a company directive that employees not take problems to directors. That one occasion was on Friday 13 September 1996, two weeks before his accident. His complaint to Mr Vanderwal was that the veering problems were caused by the truck being continually overweight "on the drive". (I will return to this particular complaint.) To his knowledge, nothing was done as a result of his complaints, the only change to the being that on the night of the accident "the truck appeared to be more rigid, more like a steel spring suspension without the variations that required the steering input".
54 It can be seen in that passage of his evidence, the plaintiff seems to have identified two problems. The first was veering from side to side in the carriageway. The second was that the prime mover would lift up at the rear as a whole or on one side or the other. The plaintiff was asked whether there was anything unusual about the way the vehicle cornered. His response that "It could do that in a corner or on a straight piece of road ...", in the context of the questions and answers seems to relate to the lifting problem. As can also be seen from the passage set out, the plaintiff was asked whether he had spoken with anybody at Tamarack "in relation to these problems" [my emphasis]. Immediately after the passage I have set out, it was established that the accident occurred at 11.45pm and then attention was refocussed on problems with the truck. Notwithstanding the earlier questions and answers, the following line of questioning, which seems to suggest three separate problems, was pursued by the plaintiff's counsel:
"And did you make any complaint in relation to the bumping that you've described?........Yes.
Who to?...........Both Rob Reynolds and John Granville.
Was that at the same time as you complained about the steering problems or at a different time?............That's at the same time.
Right. And was there any response to that?...........No.
Right. And the cornering problem that you've described, did you make any complaint about that?..............Yes.
And the same or a different time?........The same time.
And any response to that?...........No.
When I asked you about response I'm at least meaning by the question, did anything change in relation to the truck to your knowledge, did Reynolds or Vanderwal give you any answers, say what they'd do?....Yes.
Yes, and what was that?.............Rob Reynolds would say, 'I hear what you say'."
55 In cross-examination the plaintiff agreed that he first noticed something "unusual" about the handling of the truck on the first trip on the day of the accident. He said that he first experienced the handling differences on the first trip up to Tarraleah unloaded, and that the things he had earlier described about the truck's handling on the particular night were present throughout the whole of the first trip when loaded. He did not do anything when he got to Tarraleah on his first trip, to try to find out what might be different. He said that he did not give any thought to what might be causing the differences in the handling, and that it did not cross his mind to wonder about the cause.
56 The plaintiff said that the truck seemed to sit up more solidly and not roll about as much, and that this applied to when the truck was both unloaded and loaded. He was then asked whether, when he arrived at Boyer with the first load, he tried to find out what might be different, and inspected the truck. He said that he looked at the rear end of the prime mover and saw that the gap between the drive wheels and the mudguards appeared to be larger than normal. He said that normally the gap was about five inches, and that this was in both loaded and unloaded states because the airbag suspension kept it at a steady state. He said the gap appeared about three inches higher than normal. This did not sound any note of caution in his mind, nor concern him, and he did nothing about it.
"The suspension on that truck was adjustable wasn't it?..........I believe it can be yes.
Well Mr Beswick, you knew that it was didn't you?...........No.
You didn't know that the suspension on the truck was adjustable?...........No.
If you didn't know that the suspension on the truck was adjustable, didn't it cross your mind that there was something very unusual going on here if the guards were some three inches higher off the wheels, off the tyres, than normal?..........No.
Didn't occur to you to wonder why that might be so or how it had come about?..........No.
So you just got back in the truck and drove it back up to Tarraleah for another load?.........Yes, yes.
Wouldn't, wouldn't you want to know?........It wasn't unusual when you unload the truck for the actual - in the Boyer yard when I looked at the truck after it was unloaded, for when the loads taken off the airbags get a blast of air and lifts the back of the truck up so it wasn't unusual for me to see the truck actually lifted up higher in the Boyer yard. That was a pretty normal occurrence.
Well I thought you explained that when you got to Boyer you had a look at the truck and found that it was higher, that the guards were higher off the tyres than normal and that was unusual?..........Well it might be just a bit confused with how to answer this but it's unusual, if it stayed like it, it would be unusual.
So what did you do?.........I got in the truck and proceeded to do my job.
Did you have another look when you got back to Boyer after the truck was loaded to see whether that situation had changed?........No.
But you said if it stayed that way when the truck was loaded it'd be unusual so you'd want to know, wouldn't you?........No, the truck was travelling okay, it felt okay."
58 It was specifically suggested to the plaintiff that he did not notice any difference at all in the handling of the truck that night. He said that he did notice something different, that he disagreed with what was being put, but confirmed that he did nothing about it. He said that the "truck was behaving well on the road, it was actually probably behaving better. I had my shift to do and I proceeded to do my job". It was then clarified that he had looked at the gap between the wheels and the mudguards when the truck was unloaded. The plaintiff went on to say "When he was taking the load off, I noticed that the height was sitting - to me appeared to be sitting quite high, but sometimes the air bags would make it do that with the unloading process". He agreed that the situation was not unusual "in that context".
59 The plaintiff agreed that the truck was still handling well when being driven back unloaded after the first trip, better than it had previously. "It didn't require the steering input". He thought that the truck was just sitting on the road better, and that in terms of being pleased or concerned, he just did not think about the matter at all. Later, he agreed that after he had noticed the differences in the handling of the truck, he did not alter the way in which he drove. He did not drive more slowly, he did not take a different line through corners but kept driving the way he always had. He said it did not cross his mind that because the truck was handling differently "perhaps under load", he should take a bit more care, and agreed that even when loaded he made no change to the way in which he normally drove the truck, even after he had seen the height difference between the wheels and the mudguards.
The fitting of high flow HCVs to the plaintiff's truck and the alteration of the ride height
60 In cross-examination the plaintiff was asked whether he had ever had any discussion with Mr Pearton - the day shift driver - about the handling of the truck. He said he did this occasionally, discussing the problems he was having. Mr Pearton told him that he was experiencing similar problems. The plaintiff confirmed that he had complained a number of times about the handling of the truck. He said he told management that he was having veering problems and had to continually use more input into the steering to keep it under control, which he attributed to the vehicle being overweight. The question of the installation of new height control valves for the truck was raised with him. The relevant exchange is as follows:
"At some point prior to the accident it's alleged in your case that new valves, new height control valves were fitted to the truck, fast acting valves?..........Sorry, I've got to take you back to the start.
Yep, that's all right, that's my fault. At some point before your crash I think you're aware now at least that new height control valves were fitted to the truck?.........Yes.
Now, as I understand it your evidence is that you didn't know about that before the crash?...........No.
Are you telling his Honour that you had no knowledge at all that new fast acting valves had been fitted to the truck?.......Yes.
Did you know or understand that any modification had been made to the suspension of that truck?.............Yes.
Now, just to make sure you understand my question, you knew before the crash that some modification had been made?...........No, no, in that - how you put that to me, no.
So, you adhere to your evidence that you knew nothing about any modifications to the suspension before the crash?.............Yes.
Nobody ever told you that new valves had been fitted?.............No.
Nobody ever told you that something had been done to the suspension?.............No.
Didn't you tell the workshop supervisor at Tamarack that the fitting of new valves to the suspension had improved its handling?.............No, I never did, no." [My emphasis]
61 Having regard to that evidence and the position taken by the plaintiff, it is curious that in the plaintiff's case, directly contradictory evidence was introduced. This was in the form of a letter from the defendant, signed by Mr Vanderwal and dated 4 December 1996. It was addressed to a firm of solicitors which is not presently involved in the litigation. It refers to "PM15" which was the defendant's designation of the Kenworth prime mover driven by the plaintiff. The letter, signed by J R Vanderwal - Director, reads as follows:
"Approximately 3 to 4 months ago, both drivers of PM15 complained about their truck suspension being slow to level out. Upon further investigation it was found that the truck had the old (slow) levelling valves and not the quick levelling valves which the truck was specified.
The new valves were supplied by Kenworth Tasmania under warranty, and were installed by workshop staff.
Both drivers praised the new levelling valves to our workshop supervisor. No further action was taken. ..."
The specifications for the prime mover with the date of manufacture of February 2006 are in evidence, but they do not show anything other than that the rear suspension was the WD2-460. As I have noted, the WD2-460 specifications speak of high flow height control valves which may be fitted as an option "to achieve exceptional roll control with improved air system response times". In all of this, it is unclear whether the quick levelling valves referred to in the letter, were the standard valves in the suspension's 2000 specifications, and whether the high flow valves referred to in that document are a further improvement.
62 Another curious aspect of the plaintiff's case occurred in relation to the alleged alteration of the ride height of the suspension on the day of the accident. It will be recalled that a particular of negligence alleged, is that the defendant allowed Mr Pearton "to interfere with the mechanism of the levelling valves of the suspension system". The plaintiff was asked whether he had met with Mr Vanderwal after the accident. He said he had, and that Mr Vanderwal told him that the ride height of the suspension had been raised on the night of the accident This had been done by the adjustment of the "levelling valve that controls the air flow to the airbags on the drive suspension." The plaintiff said that he had not previously been aware of this. But the issue was more dealt with in far greater detail in re-examination. The passage is as follows:
"You were asked this question Mr Beswick, 'Did you ever have any discussion with Michael Pearson [sic] about the handling of the truck?' You were then asked in relation to discussions before the accident, have you had any discussion with Pearson [sic] about the handling of the truck since the accident?.........Yes.
And the - when was that or when were those discussions?..........He came into the hospital to visit.
Yes...........And I've passed him twice on the footpath, just generally passed him.
Right, and what has he said about the handling of the truck in those discussions or on those occasions rather?.............Could you -
What has he said about the handling of the truck on those occasions?.............It was standing up well.
And did he say why?.............He had a play with the levering valves on the way back on his, previous shift to mine.
Did he explain what play with the levelling valves meant?.............No, but what he said to me 'I had a play with the levelling valves on the way back. She's standing up - I've got her standing up', referring to the truck as her."
63 It will be remembered that Mr Brazendale said that it was probably seven or eight months after the accident when the plaintiff's truck came back after being repaired. He said, "at the start it was a new truck to me because I'd never driven an airbag truck before, so it was sort of different, but after a while it was - it wasn't the best vehicle I've ever driven. [It]just never seemed to sit up properly on the road - like it wanted to lay over all the time, in the corners". He said that as a consequence he had to change his driving style in that he had to be a little bit more careful and more conscious of what he was doing.
64 I have already noted the evidence of the plaintiff's experts as to this issue. In his examination-in-chief, Dr Prem was asked about the plaintiff's evidence in relation to the behaviour of the truck on the night of the accident; in particular, his evidence that:
•
the truck appeared to be more rigid, more like a steel spring suspension without the variations that require the steering input;
•
the prime mover did not display any wandering characteristics or veering;
•
it felt a lot more rigid, similar to a steel spring suspension.
"You, as I understand it, were asked to assume, at least in part, that a modification may have been made to the suspension on this truck for the crash which involved the fitting of faster acting height control valves. Is that correct?.............That's correct.
Is the description there given by the plaintiff of the behaviour of the truck, consistent with the fitting of faster acting height control valves?.............Yes.
Is it consistent with faster acting height control valves doing their intended job? Performing their intended function?.............Yes, it is."
66 There are a number of factual issues which arise from this discussion about the prime mover's suspension and associated matters. The first relates to the Hendrickson WD2-460 suspension itself. I am satisfied that the suspension system had the characteristics, and suffered from the problems, as described by Mr Lambert and Dr McLean and which I have set out. As I have noted, there was no real challenge to this evidence. There was a debate between Mr Lambert and Dr Prem about what the purpose of the system's design was, but in essential terms, Dr Prem's brief evidence did not raise any fundamental contradictions. The point of departure arose in relation to the effect of the fitting of high flow HCVs. Leaving that to one side, in simple terms this means that there was a factor of instability inherent in the suspension system.
67 The more acute manifestation of that instability was in the way in which it operated when the vehicle negotiated successive opposite corners. In a right hand corner for instance, the system operated to raise the near side chassis height to neutralise the effect of the left hand roll. Depending of course on the distance between corners, that would still be happening when the truck quickly exited that corner and entered a left hand corner. This would exacerbate the right hand roll. All of this was in turn exacerbated by the application of power.
68 In general terms, whilst the fitting of high-flow HCVs may go some way to alleviate the problem, the essential difficulties would remain. The degree to which they would be manifest would depend upon the actual level of flow achieved, the degree of roll of the truck to which the suspension had to respond and the space in terms of time and distance between corners or other events such as road unevenness, which would trigger the activation of the airbags. For those reasons the airflow may not be quick enough to have any meaningful effect, particularly given the speed at which the truck moves and the suspension needs to respond.
69 The rate of air flow was not the only problem. Dr McLean described the problems with the point of load bearing which arose because of the rigidity of the trailing arm. From about 2000, flexible trailing arms were introduced on such systems to mitigate the effects of the rigid arms. This itself might suggest that high flow HCVs were not seen as a panacea.
70 All of that leads to a consideration of what the defendant knew or ought to have known in relation to the inherent characteristics of this suspension system. I leave to one side for the moment, what may arise from the complaints which the plaintiff says he made. The present focus is on whether the defendant was negligent in providing the truck which had this particular suspension system fitted to it. I am not satisfied on the evidence, that in 1996 the level of understanding of the problems to which this type of suspension system might give rise, was such that the defendant knew or ought to have known, that its use on a log truck would give rise to a foreseeable risk of injury. In September 1998, the Federal Office of Road Safety instigated an inquiry involving a number of heavy vehicles, some of which at least, were equipped with WD2-460 suspensions. Dr McLean was involved in the investigation and I infer from his evidence that the need for it arose from reported handling difficulties, if not a number of accidents, which had occurred. The resultant report was not available at the time at which the plaintiff was provided with this truck to drive, or when this accident occurred. Further, these types of suspension systems are still generally in use, although with some modifications.
71 The next factual issue is the plaintiff's complaints to the defendant, when it was that the high-flow HCVs were fitted to the suspension, and what effect that had. I accept the plaintiff's evidence that he complained to the defendant's management, on more than one occasion, about the handling problems. I am satisfied that the high-flow HCVs were fitted an appreciable amount of time before the accident, and I infer that such fitting was done, at least in part, as a response to those complaints. One of the particulars of negligence alleged is that levelling valves were fitted which "were unsuitable and/or not in accordance with the manufacturer's specifications". There is no evidence at all that the valves were not in accordance with the manufacturer's specifications, and to the extent that the allegation means anything other than the valves were ineffective as a solution to the problem, it is unsustainable in fact.
72 Questions of precisely when that fitting occurred and what effect it had are inter-related. The letter from Mr Vanderwal, tendered in the plaintiff's case, suggests that the valves were fitted at some time between the first week in August 1996 to the first week in September 1996. At the most that would be about six weeks before the accident; about two weeks at the least. The plaintiff was not challenged in his evidence that he spoke to Mr Vanderwal on 13 September 2006 about handling difficulties with the truck, although the focal point of that discussion seems to have been that it was the load measuring system causing overloading, which in turn caused the handling difficulties. Whether or not he spoke to anyone after that date is not made at all clear by the evidence.
73 I am not persuaded by the plaintiff's evidence that he knew nothing of the fitting of the new valves. There were two particular aspects of his evidence which cause me to approach his evidence with caution where it is challenged or contradicted. As I will discuss shortly, those aspects are his initial assertion that by taking various weights at the weighbridge at Boyer, he was able to determine the front bunk of the trailer was overloaded, and his explanation when cross-examined about the speed at which he was travelling through the corner, that the recorded speed of 72km/h was because the wheels spun off the ground as the vehicle was tipping over. This suggested to me that he may have been tailoring his evidence to match what he understood to be some of the expert evidence.
74 I am satisfied though, that the fitting of the high-flow HCVs referred to in the letter (whatever precise specifications they were), did not resolve the handling difficulties, and that they were still being experienced up until the day of the accident. The evidence of Mr Lambert and Dr McLean assists me to that conclusion. Additionally, there is evidence that subsequent improvements to the suspension system were carried out by the manufacturer. These included valves with an even higher flow rate, and the replacement of rigid trailing arms with flexible ones. Further still, for the reasons which follow, I am satisfied of Mr Pearton's intervention on the day of the accident. His raising of the ride height lends supports to the conclusion I have reached. Without him having been called, there is no direct evidence as to what he did, or more particularly perhaps, the reason for it. However, I think a reasonable inference to be drawn is that he adjusted the ride height of the suspension in an attempt to further improve the truck's handling.
75 As just flagged, the last factual issue is whether the ride height had been increased by Mr Pearton on the day of the accident, and what effect that had. I am satisfied that it is more likely than not that Mr Pearton did alter the ride height on the suspension system on the drive axles on the prime mover on the day of the accident and before the plaintiff commenced his shift. The plaintiff said that Mr Vanderwal told him that the ride height of the suspension had been raised on the night of the accident by the adjustment of the levelling valve. In the letter concerning the fitting of the high flow HCVs Mr Vanderwal described himself as "Director", and the plaintiff described him as "the principal" of the company. Mr Vanderwal was not called to give evidence. In those circumstances, I am prepared to treat the statement attributed to Mr Vanderwal as an admission. I think it is reasonably open for me to find that when the representation was made, it related to a matter within the scope of Mr Vanderwal's authority; see the Evidence Act 2001, s87(1)(b). Further, the plaintiff's evidence that Mr Pearton himself admitted he had "played with the levelling valves" to get the vehicle "standing up", is first-hand hearsay within the meaning of Division 2 of Pt 3.2 of the Act. I am not sure whether or not notice had been given under the Evidence Act, s67, but it was given without objection.
76 The next question is to what extent, and with what effect, Mr Pearton raised the ride of the suspension. The two aspects of the question are inter-related. As will become apparent, the experts have assumed varying amounts by which the ride height may have been increased, but the only direct evidence of this comes from the plaintiff. His evidence was of a three inch gap higher than normal. His answers in cross-examination about this issue were not entirely compelling, but the evidence has to be put in context. He said that he noticed a gap between the wheel and the mudguard which was higher than normal; about three inches. It was when he was pursued as to why this did not cause him any concern, that he said it was not unusual to see the truck sitting higher after being unloaded. What would be unusual, he said, is if it stayed that way. The evidence is that he did not check it again. As to the extent of the raising, the evidence does not permit a finding as to a precise dimension, but I am satisfied that it was an appreciable amount in the sense of having a noticeable effect.
77 As to the second aspect, Dr Prem's animated modelling of a correctly loaded truck showed no difference in behaviour when a ride height increase of 1.5 inches was factored in. Dr McLean said that a 38mm increase would cause increased instability, and also lead to false driver feedback. Mr Lambert said that an increase of 70mm would exacerbate the handling problems caused by the suspension itself, and that an increase could be taken to the point at which for the most part the suspension would be rigid. Whilst I had some cause to hesitate about parts of the plaintiff's evidence as I have previously mentioned, in this respect there is no reason for me to reject his evidence. It was unchallenged. I am satisfied that on the night of the accident, the truck's handling was as he described, and that it had not previously behaved in that manner. On the night, it did not veer or wander, it "sat higher", it did not roll about as much, and was more rigid as with a steel spring suspension. That situation seems close to, but not actually within Mr Lambert's description of what would occur if the increase was excessive. (It seems possible that the other handling problems which the plaintiff described were still present, but I cannot be satisfied of that).
78 On the evidence, I doubt very much that with the suspension systems available at the time, the plaintiff's description of the truck's behaviour can be explained on the basis that high flow HCV's were simply doing their job. As to the extent of the increase in height, I am satisfied that it was something in the order of two to three inches, or 50 to 70mm. I am satisfied on the basis of the evidence of Mr Lambert and Dr McLean, that the increase in the ride height would have caused a corresponding increase in the height of the centre of gravity, a degree of greater instability, and given the driver false feedback concerning the stability of the vehicle. At the very least, it would have caused the feedback problem. I will later deal with what ultimate significance any of this may have as a contributing factor in the accident.
The evidence of the plaintiff and other employees
79 I have previously described the two "bunks" on the trailer, formed by the eight bolsters, four on each side. In evidence, the plaintiff described the method of loading his truck. The front bunk was loaded first. Another person operated a log loader (normally Terry Gill), whilst the plaintiff remained in the truck. He had to do this to monitor what he described as "the air gauge or the scales". There was a gauge which was located by the side of the driver's seat. The plaintiff's instructions were to load the front bunk until the air pressure gauge reached 60 kilopascals (kpa). The plaintiff had radio contact with Mr Gill, so that when the air pressure gauge reached 60kpa when loading the front bunk, he would tell Mr Gill by radio to stop loading the front bunk. Loading of the rear bunk then continued until the pressure gauge showed 260kpa, again, at which point the plaintiff would tell Mr Gill to stop.
80 The plaintiff went on to describe an alternate load measuring device called a Lodec, which consisted of a device attached at a point where the trailer is attached to the prime mover and which has a digital display in the cabin of the prime mover. That display was in kilograms. The plaintiff said that all other trucks in the defendant's fleet were fitted with the Lodec system, and that his was the only one which did not. The Lodec system could give separate readouts for the tri-axle group on the trailer and the drive axle group or the combined weight on both axle groups.
81 The plaintiff said that the Lodec system was accurate to within 10 kilograms "so if I stood on that device it would weigh me to the nearest 10 kilo". Accordingly, with the Lodec system the truck driver could tell the loader with some precision as to the extent to which the bunk should be loaded. The plaintiff's instructions were that the truck should be loaded to the maximum amount including tolerances. I have already noted his evidence in relation to the legal axle loads. The instructions were 23.5 tonnes on the truck and 21 tonnes on the trailer, with an allowance of 1 tonne on each, giving a total of 44.5 tonnes; 42.5 tonnes without the tolerances.
82 In contrast to the Lodec system, the air pressure system on the plaintiff's truck had an analogue gauge. The plaintiff confirmed that the system on his truck did not enable a separate measure of the load on the drive axle group as distinct from the tri-axle trailer group. There was no evidence as to what pressure was measured by this gauge; it may be assumed the pressure in the airbags of the suspension system. The plaintiff said that if the truck was moved, the gauge would move. Moreover, the plaintiff said that the gauge would vary considerably at times. If the truck was a down an incline "it wouldn't come up as normal". The reading would be lower. This was not explained, but I assume that the plaintiff meant lower than might have been expected having regard to the amount of logs on the trailer at any point in time. The plaintiff said that each load was weighed when he got to the Boyer mill. That is to say, the truck and trailer were put on a weighbridge and deducting the tare weight of the truck and tailer (14 tonnes) from the total load, gave a weight for the logs. He said that the weighbridge weight was either close to what the weight on the truck should be, or it was "way overweight". There was no instance of it being "way underweight".
83 At this point, the evidence is a little confusing. This suggests that the truck was overweight in terms of the total weight. I have already referred to the plaintiff's complaint that the truck was regularly overweight "on the drive". He explained his comparison of weights to mean the actual weight against what weight was intended to be achieved by the pressure gauge readout figures about which he had been instructed. However, he went on to say that he sometimes drove the drive wheels of the truck onto the weighbridge, leaving the trailer off, to determine the differential weights as best he could. He was asked what he discovered from that practice. He said "It was always on the drive - on the truck", from which I infer, (having particular regard to answers he later gave in cross-examination), that he was saying the greater part of the weight of the load was on the prime mover.
84 The plaintiff said that he raised his concerns about the weighing system with Messrs Reynolds and Cox. He said he told them that the truck was continually overweight and that he believed this was causing the veering problems. He said this overweight issue was raised at the same time as his complaints about the handling difficulties. As I have previously noted, on 13 September 1996 he spoke directly to Mr Vanderwal about the veering problems being caused by the truck being overweight. Mr Vanderwal told him that they were looking at another device but did not want to fit a Lodec system to his truck because it would intrude on the weight the truck could carry. The plaintiff explained that the Lodec device was of considerable weight, and that would reduce the payload the vehicle could carry. There is evidence that the tare weight of the plaintiff's truck was 1.9 tonnes less than at least one of the others in the defendant's fleet.
85 In cross-examination, the plaintiff said that normally the loader operator depended on him reading the air pressure gauge in order to tell the operator when to stop. He agreed that it was the responsibility of the truck driver to monitor the amount of logs being put on the truck, and the responsibility of the driver before leaving the coupe to ensure that he was satisfied "that he has a proper load". He agreed that at Boyer, the system was that the truck and load were weighed on the weighbridge, the load was then taken off, the truck and trailer were then reweighed on the same weighbridge, with a docket being produced on the second weighing. The driver handed those dockets into the defendant's office at the end of the shift. An example docket was tendered. (This was actually the docket for the plaintiff's spilt load, ultimately taken to Boyer at 8.06 am by another driver on a different truck.) As well as showing times in and out, it shows "weight in", "weight out" (the tare weight of the truck), and "nett weight" (the weight of the load). (With this docket the figures were 42.1, 15.9, and 26.2 tonnes respectively.) The plaintiff was asked about the frequency with which he found that the loads were way overweight. He said that about 80 per cent of loads were "way overweight" which he explained to mean "probably two to three tonnes", although he said that some loads were up around 48, 49 and over 50 tonnes.
86 The plaintiff was asked about his method of establishing the distribution of the weight of the load:
"Now you just weigh the whole combination don't you?......Yes.
So you would never know, even if you had an overweight on the weighbridge at Boyer, how much of that overweight was on the rear bunk and how much was on the front bunk?......Yes, I would.
How would you know that?......When - if the mill wasn't busy quite often I would check the truck and the trailer independently to try and ascertain some kind of system to use with the air gauge to try and better it.
Yeah, when did you start doing that?......Quite often during the course of the vehicle - use of the vehicle.
Yeah, when did you start doing it?......I'd say pretty much when I immediately went on the vehicle.
Did you come up with any figures that you could use?......Not in accordance with the air gauge, no, because - I'll give a reason if you like?
No, just let me ask you this question though. How often did you find that the weight on the front bunk was more than you expected?......Every time I checked it.
Every time you checked it?......Yes.
And that started back in May?......Yes.
So in June - through June you weighed on some occasions independently the front bunk and the rear bunk or the drive wheels and the tri-axle wheels?......Yes.
And on each of those occasions you found your front bunk was overloaded?......Yes."
87 In cross-examination, the plaintiff agreed that he said nothing to the loader operator, Mr Gill, about the issue, or did anything differently in relation to the gauge readings. He said he first started doing the checks in May 1996 and he continued to do them about two or three times a week. He said that mainly when he experienced a lot of problems with the vehicle, he would check it "just to see where it was". He said he regularly discovered that the front bunk was overloaded. The following questions and answers relate to how it was that the plaintiff was able to establish a differential in weight, and to ascertain what sort of weight was on the front bunk:
"What sort of weights were you getting?..........Anywhere from the forty-five up to sixty-one tons, that's the gross combination.
No, no, I'm talking about the front bunk?........I can't, I can't remember specifically, I can't remember specific weights -
You can't remember?..........I'd have to write them down to remember it.
Well, how much would you have expected to find on the front bunk?...........Twenty-three and a half -
Twenty-three and a half. Well, how much over that were you consistently finding?..........Some occasions I was up over twenty-six, I remember, or more.
Twenty-six tonnes on the front bunk?............Yeah.
Twenty-six tonnes on the front bunk?.........Yes.
That's out of the gross combined mass is it?.........Yes.
Did you have any idea, did you have any idea how much that meant you had in pay load on the front bunk?.........Yes, I would.
Well, what was it? If you had twenty-three tonnes weighed on the drive wheels, what was your pay load on the front bunk?.........It would be in excess of thirty tonnes.
In excess of thirty tonnes. It can't be can it?.......Why?
That's nonsense. If you had a gross combined mass on your drive wheels of twenty-six tonnes you couldn't have a pay load of thirty on the front bunk?..........I'd say it would be in excess of thirty tonnes, yes.
Mr Beswick when you talk about individually weighing the front and rear bunks what you mean is this isn't it, you would position your truck so that the weigh bridge weighed the load - sorry, I withdraw that - recorded the weight on the drive wheels?...........That would be the drive wheels and the steer wheels.
So, the whole prime mover?.............The prime mover.
So what it would be recording was the weight of the prime mover...........Yes.
The whole prime mover and at least some of the weight on the front bunk...........Yes.
Now, you're telling us that on occasions you were getting weights of 26 tonnes for the prime mover and some of the load on the front bunk. Is that right?.............Yes, yes.
And I understood you to say that you knew from that what weight of logs you had on the front bunk...........Yes.
And you're telling us that was 30 tonnes...........Well, actually no because I'd have - I just take that back. You'd have to come, you'd have to weight just the prime mover independently of the trailer on the way out and then take that from the first weight and I never did that, no.
No, none of this ever happened, did it, Mr Beswick...........Yes, it did.
You never really had any idea at all what weight you had on the front bunk...........It did happen and I did have an idea, yes.
All that you knew was what weight you had on the truck as a whole from the weigh bridge dockets. That's all you ever knew, isn't it?.............No."
88 The plaintiff was asked about the assessment of tonnage in any particular load. The logs carted to Boyer were pine logs. The plaintiff said that the weight of the logs depended on how long they had been harvested. The moisture in the logs dries out so they get lighter as time goes by. The plaintiff agreed that it might be very difficult to tell what weight was in any particular load of pine logs, but disagreed that an overload of two, three or four tonnes would be fairly obvious and not too difficult to spot. He said that loads were usually taken from a particular stack, so that the logs in a particular load would not differ much in nature and age from one to the other. There is no evidence of the weights of any previous loads carried by the plaintiff. There is evidence of the weight of three loads carried by a fellow employee, Graham Smith, on the day of the plaintiff's accident. This is in the form of Mr Smith's time sheet. With a tare truck weight of 15.9 tonnes, Mr Smith carried loads of 27.65, 26.60 and 29.10 tonnes. I infer that he too was instructed to load to the maximum. This suggests, as does common sense, that the actual weight of the load may be governed by the discretion of those involved in the loading process. Obviously to achieve a particular weight, a load of light logs would assume higher proportions than the equivalent load of heavier logs, and may be so high as to create a risky situation due to the location of the centre of gravity. At least with the Lodec system, far more precise weights could be determined for the drive and trailer axle groups.
89 Mr Gill gave evidence in the plaintiff's case. In relation to loading generally, he said he loaded the front bunk until it had "the right amount on it" and then the truck moved forward and the back bunk was loaded. In relation to trucks with the Lodec system, it would reveal when the right amount of weight was on the truck. However, the plaintiff "had nothing. It was guesswork." As to loading the plaintiff's truck, Mr Gill said that he usually did it by sight until the plaintiff thought he had enough. He confirmed that radio contact existed between the two and that normally it was either that the plaintiff said he had enough and then he would move forward, or if he thought there was enough, he would tell the plaintiff. He said that they would come to a decision that way and then he would move forward to the next bunk. He said that sometimes a reasonable estimation of the weight could be obtained through the "gauge set up"; other times the gauge would not move.
90 Peter Brazendale was also called in the plaintiff's case. He also drove a log truck for the defendant, starting in the early 1990s. He was working for the defendant at the time of the plaintiff's accident. He took over driving the plaintiff's truck after the accident, and after it had been repaired. He said that it was probably seven or eight months after the accident the truck came back. Mr Brazendale confirmed that when he took over the truck it still had the air pressure gauge load measurement system. He said that he had driven trucks with the Lodec measuring system. He was asked how he would compare the two systems. He said "There was no comparison". He said that with the Lodec system he could load within probably half a tonne or so, but with the air pressure gauge system "It was purely guesswork".
91 I will of course come back to this evidence when dealing with the asserted causes of the rollover, but Mr Lambert concluded that the load weighing system was "defective", in that it caused or could cause the front bunk to be significantly overloaded to the extent that the overturning moment due to load could be up to 20 to 40 per cent higher than it should have been. For present purposes, it only needs to be noted that using his assumed legal axle weight figures, for the truck to have been correctly loaded, the driver should have been told that the airbag pressure limit for loading the front bunk was 55kpa, not 60kpa. At this point, it is also worth noting the effect of disproportionate loading on the bunks. Dr McLean was shown a series of photographs depicting the plaintiff's loaded truck on various dates before the accident. (I will later discuss these photographs in greater detail.) He was asked whether they indicated to him anything about the distribution of the load, or whether he had any comment to make. He noted two photographs as showing the front bunk as more heavily loaded than the rear. He noted a further two photographs which showed "a particularly adverse load distribution", in that the stack of logs in the front bunk was higher than that in the rear. He was asked why was that adverse. He replied:
"Because you've got more load on the bogey and the bogey is most flexible component, or most - so it has the least roll resistance of the vehicle because the tri-axle is much greater stability than the bogey, so that is particularly adverse and also the other aspect your Honour, is the high centre of gravity of the load above the turntable, it's higher there than at the trailer so it's better to load the trailer because due to the slope of the chassis frame the trailer is automatically lower so you get a low centre of gravity by carrying it at the rear bunk."
92 I have grave reservations about the plaintiff's evidence of weighing the loaded truck at Boyer, and what he determined from that. I am prepared to find though, that he regularly observed what he thought to be excessive loading on the front bunk, and that he when he complained about handling problems, he related that overloading to the load measurement system. As to the further relevant underlying facts, the plaintiff and the other employees were not challenged about the nature or operation of the system. The plaintiff was not challenged as to what his instructions were in relation to the particular pressure readouts as to the load sought to be achieved, nor as to what Mr Vanderwal said to him about the fitting of the Lodec device, when complaint was made that veering problems were caused by the truck being overloaded. There is no reason to reject this evidence. I find accordingly and proceed on that basis. As indicated, I will later examine further expert evidence about this issue, and address the likely consequences of the use of the system.
93 On the day of the accident, the plaintiff started work at about 4pm. He was instructed to go to a coupe at Tarraleah and to cart pine logs to Boyer. Unloaded, the trip took about an hour and a quarter; 1½ hours when loaded. He said that he was under no time pressures. He did one load and returned for the second. He thought that the second load took about 20 to 30 minutes to put on, which was about how long it usually took. The plaintiff said that during the loading of the front bunk, Mr Gill questioned the weight or the amount of logs he was putting on. He put more logs on after questioning it, and then decided to stop loading, refusing to put on any more. At that time, the plaintiff said that the pressure gauge readout did not show 60kpa, but was less.
94 In cross-examination the plaintiff said that the pressure gauge read considerably less than 50kpa when Mr Gill stopped loading. The sequence of events was explained as follows:
"So your evidence is that Mr Gill stopped loading when the reading on the gauge was considerably less than 50 kilopascals?........Correct.
When he stopped loading, what did you say to him?........He stopped loading on the first occasion because he felt...
No, no Mr Beswick I asked you, when he stopped loading and the gauge still showed less than 50 kilopascals, what did you say to him?..........I haven't got enough weight, the gauge isn't at the 60 kilopascals to continue loading.
Did he put more logs on then?.........Yes.
And what reading was on the gauge when you told him to stop?.......I didn't tell him to stop and the gauge wasn't moving.
So am I understanding you correctly, that Mr Gill stopped loading, you looked at the gauge, it read less than 50 and you told him to put more on?.........Yes.
He then stopped loading?.........He put more on, he put, I can't remember how many grabs of logs he put on and then he stopped and then said he's not going to put any more on because he considered it to be too much.
Well is that what he said, that he considered it to be too much or did he in fact say that he considered it was loaded?..........He considered it to be too much. If I - If you'd like me to quote 'I think you've got too much'.
No, just bear with me Mr Beswick. He said to you that he would not put any more on because he considered it to be too much?.........Correct.
Did you tell him then to take any off?..........No.
But he'd already told you there was too much on there in his view?.........Yes."
95 In relation to the rear bunk, the plaintiff said that it was he who told Mr Gill to stop loading when the reading on the gauge got close to 260kpa. He acknowledged that at that point, he knew it was Mr Gill's view that there was too much on the front bunk. He said that he assessed the situation himself, comparing front to rear, and thought there was too much on there. He did not however, tell Mr Gill to remove any logs. He said that he did not do that "Because according to the gauge it was - I had to have the weight that they wanted me to cart". He agreed that due to his experience he would have been a good judge of how much load was on a truck and whether it was too much. He said that he did not make a decision that there was too much on the front bunk, but went on to say "In comparison to the amount, like the height of the load, the front bunk did appear to have too much, yeah".
"Now, you've said that on your second load on the night of the crash you left coupe as I interpret your evidence with a load that registered on the gauge at, did you say close to or at 260 kilopascals?...........Close to 260 kilopascals.
Close to. Close to under or close to - or over?...........I believe it was roughly a needle width under.
Under. You left the coupe with a load that registered on the gauge at under 260 kilopascals but with a load that you knew to be greater than, in your view, should have been on the front bunk?...........No, not greater than (indistinct words), no.
Well, you told us that you thought it was overloaded?..........It appeared to be, with the height of the load compared to the height of the rear bunks, when you load trucks to scales you roughly know how they stack up."
97 The plaintiff said that after the accident, the load was scattered down the embankment "all the way to the river". The area was "full of blackberries and vegetation". Mr Gill said that on the night of the plaintiff's accident he was called to the accident scene to collect the logs that had come off the truck. He said that he recalled putting that load onto the truck, but could not really remember what occurred during that loading, explaining that it was 13 years ago. Mr Gill's "Loaderman Daily Record" for 27 September 1996 was tendered in cross-examination. It shows 19 loads for nine different trucks, and includes the plaintiff's two loads. In a column headed "Estimated Weight", all loads were noted by Mr Gill as 28 tonnes, which he described as "general" estimates.
98 Mr Gill explained what happened when he arrived at the accident scene, which he said, was somewhere between 2am and 4am:
"Thank you, and when you got there did you see Harley's truck and trailer?.............Yes.
And where were they?.............They was upright again, sitting on its wheels and more or less alongside where the Armco railings had been.
All right and did you see the logs?.............Yes, yeah, scattered down over the bank.
Yes, and how did you go about getting the logs out? Were you able to simply use the grab?.............Yeah, put the truck back into position and pick the other logs up over the bank.
Mm...........And I was assisted by Graeme Smith with a chain so we could grab the logs that was out of reach of the boom.
Right, and you chained those logs up?.............Yeah, Graeme chained those logs up and we dragged them up, kept doing that until we got what was there.
Right.
HIS HONOUR: What did you do with them when you retrieved them from the bank?.
WITNESS: Ah, dragged them up onto the road or onto the edge of the road behind the (inaudible), undone them and them put them off the ground onto the truck, another truck that was there.
HIS HONOUR: Another truck.
WITNESS: To pick that load up, yeah.
MR READ (Resuming): And that was Mr Smith's truck?.............Yes."
99 Graham Smith was called in the defendant's case. He gave evidence of his retrieval of the logs from the scene of the plaintiff's accident. His time sheet for 27 September 1996 was tendered. (I have previously referred to this evidence.) It shows a starting time of "3.15" and finishing time of "8". The weighbridge docket and Mr Smith's evidence suggest that he finished a little after 8am. The reason for the long shift was his involvement in the retrieval of the logs. There are four entries on the time sheet which relate to loads carried. The first three are loads he carried in the ordinary course of events from Tarraleah to Boyer, the respective tonnages being 27.65, 26.60 and 29.10. The fourth entry shows a load taken from Plenty to Boyer. His evidence was that this was the load "that was lost off the truck, that fell over -". The weight shown for that load is 26.20, which of course accords with the actual weighbridge docket to which I earlier referred.
100 In cross-examination, Mr Smith was asked what the maximum load was he could carry on his truck at the time. He said that at this stage he could not remember the actual loads which were allowed. He said that they were not allowed to overload and anything over the limit was not paid for. 44.5 tonnes was put to him as the maximum tolerance. He said "42 or something". He replied "Something like that, yeah" to the proposition that it was 42 or 42.5, but said that it should not be as high as 44.5. It was pointed out to him that one of his loads was 29.10 tonnes which, given the tare weight of his truck at 15.9 tonnes, gave a total weight of 45 tonnes, being three tonnes over the limit if the limit was 42 tonnes. Mr Smith responded that he was not sure, it was 13 years ago, and he was getting "old and forgetful".
101 There are two issues which arise in relation to the particular load. The first is its weight; the second is its distribution. As to the weight of the load, I am unable to say that it is more likely than not that it exceeded 26.2 tonnes. The evidence does not permit a positive finding that it was greater than that. Whilst it is possible that some logs were lost into the river, and hence that the load weighed more, the evidence taken as a whole does not justify that finding. There is no evidence that this was an unusually light load. In reaching this conclusion, I have also taken into account the evidence of the weight of the three other loads which Mr Smith carried that night, and which I have set out above. Those weights have to be put along side the fact that the tare weight of his truck was 15.9 tonnes and was equipped with the Lodec weight measuring system. One of its loads was 26.6 tonnes, and in this context, I repeat that I infer from the evidence that he would also have been instructed to load to his truck's maximum capacity. There is no evidence that of itself the weight of this load was in excess of a safe load, and there is therefore no factual foundation for particular of negligence (a)(ii), which alleges a load weighing "in excess of the safe load", to the extent that it is intended to be directed at the weight of the load as such.
102 As to the distribution issue, the word "overload" in this context, is a relative term. Whilst the truck may not have been overloaded in the absolute sense of its GCM, it may have been overloaded in that one or other of the drive axle pair, or the tri-axle group, bore a disproportionate part of the load. The effect of such overloading depends on the overall weight and the extent of any disproportion. As to the facts, I accept that Mr Gill stopped loading the front bunk because he considered there was already too much on it, and that he said words to that effect to the plaintiff. At that stage the gauge was reading less than 50kpa. More was then put on. The total loading process ended when the plaintiff told Mr Gill to stop loading the back bunk when the gauge was reading close to 260kpa. I accept that at that point, the plaintiff thought that too much of the load was on the front bunk. I think the probabilities are that the front bunk bore an uneven share of the load, and hence the drive axles were overloaded, but here again, this is an issue to which I will return in ultimately considering the cause of the rollover.
103 The plaintiff was reminded that he had given evidence of how he usually drove around the Plenty bends, and asked how he did that on this particular occasion. He said that it was the "normal" way he drove around the bends, with the same amount of engine revolutions, speed and gear changes. Up to the sixth bend he said there was nothing different about his method of driving than usual. As to the sixth bend, his evidence was then as follows:
"The truck - going round there the truck veered to the right, I steered to the right to try and keep control. It was clear I didn't have control of the vehicle so I...
Sorry can I just stop you there? Why did you steer to the right rather than to the left when it's now going towards the wrong side of the road?........This was a significant veer - the whole weight had taken over the vehicle; the feel of the vehicle, I had to steer to the right.
Okay sorry, keep going..........I steered to the right to try and balance the load. It was clear that I just was not going to get - I didn't have control of the vehicle and I hit the brakes to try to stay with that for a moment but it was just obvious that it wasn't going to come back, I wasn't going to get control of the vehicle, so I hit my brakes as hard as I could, pushed as hard as I could, and shut the engine down - the vehicle down with the brakes, stalling the engine."
104 He said that the truck went some distance across towards a tree. This tree is shown in photographs which were tendered. It is a large gum tree on the right hand side of the road just after exiting the bend 6 at a point where the road has straightened. There was Armco railing on the right hand side of the road for the entirety of the five bends. Just before reaching the tree, there was a gap in the railing for a track leading down to the river. The plaintiff said that the truck went towards the tree, "... took out a section of guardrail and went on its side and I remember seeing the tree and I knew the cab was going to come in contact with the tree".
105 He said that the cab of the truck came to rest against the tree, lying on its right hand side with the trunk of the tree parallel with the windscreen. He had to climb out through the passenger side door, standing on some logs that had broken through into the cabin. Later in his evidence the plaintiff said that it was at about the apex of the bend at which he steered onto the incorrect side of the road and that it was the right front (steer) wheel of the prime mover which first crossed over.
106 In cross-examination, the plaintiff said that on the first trip, he had not driven slower than he normally did, nor took a different line. As to the second trip he said that he had gone around the sixth bend at "Approximately between sixty and seventy kilometres an hour, around seventy kilometres an hour." When pressed, he agreed that it would have been closer to 70km/h, but said that he did not look at the speedometer on that particular bend. He was asked whether he accepted that his speed around the last bend on the second trip when the crash happened, was 72km/h. He said that he accepted about 70km/h. He was asked whether there was a reason for challenging the extra two km/h. He replied that the drive wheels "actually spun off the ground on the vehicle as the vehicle was tipping over". He said he was aware that the Tripmaster graph showed that at a particular point the speed increased from 70km/h to 72km/h, and agreed that he had "come up with the explanation" that the increase in road speed as shown on the graph, is to be attributed to the drive wheels lifting off the ground.
107 In the final part of the relevant exchange, the plaintiff accepted that he drove into the corner at 70km/h as he had done on the first trip on that day. In further cross-examination, the plaintiff agreed that the Plenty bends had an advisory speed of 55km/h, and that he had driven into the sixth bend at 70km/h, some 15km/h over the advised speed. He said that he had driven into and through other bends between Tarraleah and Boyer that night where there were advisory speed signs, at similar amounts above the advised speeds. He was not challenged in cross-examination about the line he had taken through any of the four corners of the Plenty bends leading up to the point of the accident.
The cause of the rollover - the expert opinions
108 I need to say something about two categories of photographs which were in evidence. The first category is comprised of photographs of the accident scene and upon which each expert witness commented. I have already mentioned the second category which consists of photographs of the plaintiff's truck taken, I infer, at various times from when he first started driving it up until the day of the accident. They show the truck loaded with logs of a similar type to that carried on the day of the accident.
109 Of course, photographs may be used as material to understand the evidence. On their own, they may have some probative value, but care needs to be taken to ensure that they are not used as the sole source from which a primary fact is to be inferred where that fact is not revealed on their face. Photographs can be used to establish such things as approximate distances or dimensions, where the evidence otherwise establishes the dimension or location of an object, provided great care is exercised. Apart from that, I am able to act on the interpretation of persons with appropriate skill and experience; see Blacktown City Council v Hocking [2008] NSWCA 144, per Spigelman CJ, at [7] - [13], per Tobias JA at [167] - [170], and Warren v Gittoes [2009] NSWCA 24, per Hodgson JA at [2] - [3].
110 As to the first category, in each of Mr Lambert's and Dr Prem's case, their opinions were in part based on what they derived from skid marks shown in these photographs. Two in particular were the subject of debate: numbers 38 and 42. (Enlargements of those were marked as P18A and 18B.) One is taken on the western or river side of the roadway looking generally south; the other from the same side of the roadway but generally looking southwards and northwards. I have already noted that the photographs of the scene in evidence were taken at an unspecified time, but apparently shortly after the accident and by an unidentified person. An A3 size enlargement of each of the two photographs was put in evidence, as were copies of colour enhanced versions produced by Mr Lambert. The point of debate was what skid mark, or marks, could be discerned from the photographs, and what significance, if any, those marks had in determining the cause of the rollover.
111 At first glance there is a single skid mark on the plaintiff's incorrect side of the road starting from about the middle of that laneway and veering across, ending at a point a very short distance inside the fog line. Mr Lambert said that he could discern in the skid mark, two marks consistent with the bogie drive of the prime mover, from which he inferred that the rollover commenced from those drive wheels. Dr McLean took the view that there was an absence of marks he would have expected to see, and that the mark had nothing to do with this accident at all. Dr Prem said that it was one mark consistent with it being left by the near-side steer wheel of the prime mover, this being supportive of the proposition that the rollover commenced from the rear of the trailer. I will, of course, return to these theories themselves, but say at this point that I find these interpretations of the photographs of little assistance. There was also an issue about what was to be made of the nature and extent of damage to the Armco railing shown in the photographs.
112 As to the second category of photographs, Mr Lambert produced a detailed analysis of these photographs to demonstrate features of the general load distribution of the plaintiff's truck resulting from the particular load weighing device which was used. I will shortly turn to that evidence. These are the photographs which were shown to Dr McLean in the course of his evidence and about which he expressed a view. The same principles which I have earlier set out also apply, of course, to the approach to this category of photograph.
113 In his first report, Mr Lambert identifies five possible "causative elements". The second one is that the load "may have been slightly off centre due to the log sizes and placement". Mr Lambert says that no opinion can be expressed as to whether this may have been a factor, and it was not pursued in the trial in any way. The remaining four, each of which are said to have "significantly contributed to the rollover" were:
•
The "unusual" system of determining the weight of the load.
•
The WD2-460 suspension system.
•
The fitting of high-flow HCVs "two days before the rollover".
•
The raising of the height setting on the suspension "on the previous shift".
114 This first factor as further explained is that "the system used to determine the weight of the load was unusual in that there was only one weighing device for the two axle groups supporting the load - the drive axles and the tri-axle group". Mr Lambert's final conclusion is that the weighing system caused, or could cause, the front bunk of the trailer to be significantly overloaded to the extent that with a correctly loaded combination, the overturning movement due to the load could be up to 20 to 40 per cent higher than it should have been. Leaving aside an analysis of a series of photographs to which I have referred, the reasoning in the written report leading to this conclusion is, to me at least, a little hard to follow, with a series of observations and assertions, about some of which there is no evidence. It was not explained in examination-in-chief. However, the thrust of the point seems clear enough. The analysis of the photographs as contained in the report has its own difficulties which I will detail in a moment.
115 Mr Lambert (correctly) assumed that the system consisted of an airbag pressure sensing gauge in the cabin, attached to the rear suspension. He also correctly stated that the procedure was to load the front bunk until the pressure on the air pressure gauge reached a certain reading, and then to load the rear bunk until a higher pressure was achieved. Mr Lambert's reasoning is based on a normal load of 28 tonnes with the tare weight of combination given as 15.5 tonnes. That total of 43.5 tonnes was based on the assumption of a .5 tonne tolerance for each of the drive axle and trailer axle groups, which is not the evidence of the plaintiff, who gave evidence of a tolerance of 1 tonne for each axle group. The tare weight figure is also incorrect, the evidence from the plaintiff being that the tare weight of his combination was 14 tonnes. In a particular photograph of the plaintiff's loaded truck, Mr Lambert estimates that the height of the load in the front bunk is about 2.1 metres, making the overall COM 3 metres. Assuming this was an average load, the relevant height of a maximum load would be about 2.4 metres.
116 From that basis, the key aspects of the reasoning seem to be as follows:
•
nearly 15.5 tonnes (about 55 per cent) of the 28 tonnes would be supported on the trailer axle group;
•
his modelling showed that around 82 per cent of the front bunk load would be supported by the kingpin and turntable, and 18 per cent of the front bunk load "through the trailer group axles";
•
the centre line of the front bunk is about 700mm behind the second drive axle, but loaded, the location of the COM along the vehicle could vary by plus or minus 200mm;
•
if the vehicle were located on a slope when loading, then assuming a slope of up to plus or minus 4 per cent, the COM of the load could move forward or back another 120mm.
"Hence total variation may be up to plus or minus 320 mn. In turn this would mean that if the triaxle airbag pressures were used as a load mass indicator for the front bunk, then the variation in the weight logs loaded in the front bunk could be up to 5 tonnes (that is + - 2.5 tonnes).
In addition the rear bunk load could be similarly affected with a variation of 1.2 tonnes, (that is + - 0.6 tonnes) going on to kingpin. Hence total variation could be + - 3.1 tonnes."
118 The essential proposition is that by calibrating the relationship of the mass of logs at the front bunk to the airbag pressures on the tri-axle group, an error occurs which biases the loading towards overloading the drive axles. The end result of this is an increase in the overturning moment (the mass in tonnes by COM height in metres) by about 20 per cent. In the report Mr Lambert said: "And even the average load may have been an overload situation, so that the overturning moment due to the load may have been up to 40% higher than when legally loaded. This would significantly increase the chance of rollover of the front of the trailer." It would pay to set out at this point some of Dr Prem's figures relevant to all of this. He assumes tare weight tonnages of 5.5, 4.0, and 4.5, for the steer axle, drive axles, and tri-axle group respectively. "Correctly loaded", he says the axle loads would respectively be 6 tonnes, 16 tonnes, and 20 tonnes. Using those figures and assuming the same distribution, with a 26.2 tonne load, the "desired" axle loads become 4.7, 11.23, and 14.5 tonnes respectively. A 20 to 40 per cent increase on the drive axle groups, with that load, results in a 13.47 to 15.72 tonne loading on the drive axles.
119 In support of the proposition, Mr Lambert analysed 14 photographs showing the plaintiff's truck loaded with logs of a similar type to that carried on the day of the accident. Making the assumptions as to the legal axle limits which I have noted, with a tolerance of 1 tonne on the drive axles and the trailer axles, by use of known truck and trailer dimensions, Mr Lambert calculated from the photographs that on average, the loads shown were 113 per cent of the legal limit for those axles.
120 There are, however, difficulties with Mr Lambert's analysis. The first report as tendered contains the photographs with comments underneath, which include the estimated percentage proportion of payload in the front bunk, and the indicative weight on each axle group, if the GCM is 43.5 tonnes. Figures for the steer axle, the tandem drive axle and the tri-axle group are given for each photograph. It might have been assumed that the total load set out in relation to each photograph would have been the same; that is, 43.5 tonnes being Mr Lambert's estimate of the tare weight of 15.5 tonnes, plus the assumed load of 28 tonnes. However, the total weight in respect of five photographs is 43.6 tonnes, whilst two are given a total weight of 43.4 tonnes.
121 This analysis was carried out on the basis of the assumed tolerance of 0.5 tonnes rather than the 1 tonne in accordance with the plaintiff's evidence. In Mr Lambert's evidence-in-chief, a table of recalculated figures was tendered. His evidence was that he did the recalculations "based on the weight indication system on the truck being designed such as to get about 21 tonnes on the triaxle group". In the table, 21 tonnes is a figure ascribed to the tri-axle group for each photograph, with differing figures given for the steer axle and the drive axles.
122 The total of the weights on the various axle groups does not in each instance add up to 43.5 tonnes. It varies from 44.9 tonnes to 47.6 tonnes. I raised with the parties the point that the table did not seem to be based on an assumption of a total GCM, and asked whether the evidence disclosed how the weight figures for the steer axle and drive axle group were arrived at, given the constant figure of 21 tonnes for the trailer axle group. The plaintiff agreed that no assistance could be found in the evidence. The defendant pointed out that the assumption that the total weight of the tri-axle group was 21 tonnes, was an unlikely assumption and highlighted the unreliability of the assessment.
123 As noted above, Mr Lambert was proceeding on an estimate of the tare weight of the plaintiff's truck of 15.5 tonnes. In cross-examination, Mr Lambert agreed with the proposition that logging trucks, at least until the early part of this decade, were recognised as a particular group of heavy vehicles frequently operated with SRTs of less than 0.35g. However, he disagreed with a further proposition that in 1996 that the plaintiff's truck, "in terms of its SRT when loaded would have been on a par with most or all of the logging trucks operating in this country at that time". He said that, "It was a particularly light vehicle therefore its SRT would be worse. Its tare weight was particularly low". He went on to say that he had been advised by the plaintiff that it was "fourteen point something". He said that he did not have confirmation of its exact weight, but he accepted that the weight of the combination was in the range of 14 tonnes. The next question and answer were as follows:
"In 1996 I suggest in fact this truck would have been very little different to most others, most other logging trucks I should say in terms of its SRT when loaded?.........It would have been worse because of the light tare weight of the combination."
124 Mr Lambert agreed that he had not been given any tonnage figures for what might have been the weight of the plaintiff's load. He said that he had based his reasoning and opinions on a range of payloads, but confirmed his view that the front bunk was overloaded in the sense that of the total payload, too much was on the front bunk. He said:
"The weight indication system basically determined the weight on the tri-axle group of about 21 tonnes. The design and calibration of that unit from my calculations showed that the front bunk was then - when that was 21 tonnes, the front load bunk would be overloaded and the vehicle would be overloaded."
125 What Mr Lambert meant by basing his opinions on a range of payloads, was neither clarified in cross-examination nor explored in re-examination. In further cross-examination, Mr Lambert said that:
•
his conclusions as to the distribution between the front and rear bunks was based not only on the photographs, but also on the known dimensions of the trailer, and calculations based on the geometry and size of the airbags for the drive suspension and the trailer suspension, together with the relevant pressures;
•
the biggest variation in weight (by which I understood him to mean the estimate of load on the drive axles) arose because the slope at the point at which the vehicle was loaded was unknown. He said that if the vehicle was on a downwards slope that would increase the weight on the front drive dramatically. Using an air gauge on the rear as the indicator if the brakes were applied, that would affect the way the suspension reacts;
•
if there had been a reliable independent source of the probable weight of the actual load, "that would have been marvellous";
•
with the photographs and information provided, an estimate of weights could be made, giving "some idea of how much the drive axle group would be overloaded ... The only conclusion would be that ... it's likely that the drive axle was overloaded by between 5 and 14%";
•
because overloading had happened on perhaps 14 previous occasions, it was possible, rather than likely, that it had occurred on this particular time.
126 Mr Lambert was pursued further as to his lack of information as to the loads on the plaintiff's truck in conducting his analysis. The questioning continued as follows:
"No. Well you said you weren't given weighbridge tickets my question was any information at all about what weight was on - take photograph 1......The only information I had initially was that the loads were likely - the target weight of the combination was forty three and a half tonnes, that's all I had.
Forty three and a half tonnes......At that time, yes.
So is it correct that you have assumed - you've started with the premise that the weight of the load on the truck in each of these photographs was forty three and a half tonnes?......No, the total weight of the combination including the tare weight of the trailer and prime mover was forty five tonnes.
I'm sorry, the total gross combined mass, the GCM?......Yes.
Yeah. And that's the premise you've started with in your analysis of each of these photographs?......Yes."
127 He agreed by way of an illustration that overloading on the front bunk was relative to the total payload, so that with a very small total payload there was only likely to be an overload on the front bunk. He went on to explain that the rollover stability of the combination had to be seen in two components; one was the rear tri-axle group and its load, with the second being the front bunk and the drive axles. There was a separate SRT in respect of each. He said it was possible to have a lower SRT on the rear than the front, which was the most common situation, and such vehicles would normally roll from the rear, "or you can have a situation where the SRT on the front is lower than the rear then you expect in that case the vehicle could roll over at the front".
128 Mr Lambert then confirmed that he started with the premise that the indicated target weight was 43.5 tonnes, and that he set out to make an estimate of how much of that 43.5 tonnes was on the front bunk and how much on the rear bunk. Mr Lambert agreed that in addition to the two points he had noted which made the methodology imprecise, the absence of actual load weight was a variability affecting the assessment of the photographs. The point was not taken up but it seems that Mr Lambert's reference to 43.5 tonnes and then to 45 tonnes, came from his initial reference point using the 0.5 tonne tolerance, which was revised upwards and ought, of course, to have resulted in a 44.5 tonne indicative weight. The reference to 45 tonnes would seem to be an error.
129 I should note before leaving this issue however, that Mr Lambert's evidence about the overloading on the front bunk was supported, in general terms, by Dr McLean's evidence upon being shown the photographs whilst he was in the witness box, which evidence I have previously set out. In turn, of course, this expert evidence corroborates the plaintiff's evidence as to the load on the front bunk on the night of the accident.
The suspension system, the HCVs and the raising of the ride height
130 I have already dealt with Mr Lambert's opinions as to the causative contributions that these matters might have made, together with his additional evidence and cross-examination in the trial. Mr Lambert's second and third reports were by way of response to Dr Prem's first report. Although these aspects of his evidence were given in the normal course of things, I will deal with this evidence when considering that of Dr Prem, as it is more convenient to do so.
131 Again, I have already detailed much of Dr Mc Lean's evidence relating to the suspension system and the raising of the ride height. Primarily, his first report was directed to an interpretation of the data from the Tripmaster system printout, or "vehicle event log". The log shows vehicle speed noted as a "*" symbol, and the engine rpm shown as a "+" symbol, on two horizontal axes. The speed has a range of zero to 130km/h, with the rpm from zero to 2,500. Time is shown on the vertical axis of the log. The exhibit starts at 23:38:24 hours. It concludes at 23:41:34, but the truck seems to have come to a stop both in terms of speed and engine revolutions at 23:41:29. On another vertical axis "switch actuations" (brakes) and "switch 2 actuations" (engine brakes) are shown as "X" and "Y" respectively. This detailed data is also represented in another document; a vehicle event graph. This shows vehicle speed as against time in one graph, under which is engine rpm against the same timeline, under which again is a representation of the application of brakes and engine brakes by black lines as against the timeframe.
132 Working from all of this, and with known distances and photographs, Dr McLean was able to provide the following summary of what had occurred:
•
the truck's speed was 70km/h per six seconds before commencing to negotiate the sixth bend. This was between 232 to 135 metres from the final resting place;
•
on approaching the corner's apex, and until slightly after the apex, the nearside drive wheels suddenly lifted up from the roadway and the indicated vehicle speed rose to 70km/h;
•
the nearside drive wheels were not in contact with the roadway for three seconds over the distance 135 to 75 metres from the final resting place. The first event of lifting occurred at about the 125m mark, with the second happening between 75 metre and the 55 metre marks;
•
the sudden increase in indicated road speed confirms that there was a steering/handling deviation precipitated by the vehicle's drive wheels;
•
after the corner's apex, and after the nearside drive wheels reconnected with the roadway, the vehicle's speed was approximately 70km/h, some 55.5 metres from final resting place;
•
shortly after the steering/handling deviation, the plaintiff commenced to reduce the vehicle's speed by easing off the throttle, followed by the application of the vehicle's engine brakes. This reduced the speed to approximately 58km/h when 19 metres from the final resting place;
•
at that distance, the plaintiff applied controlled vehicle braking which continued to be applied up until the vehicle came to rest. When travelling at approximately 45km/h and approximately 13.5 metres from the final resting place, the vehicle impacted the guardrail.
133 Dr McLean says that the fact that the indicated road speed suddenly increased confirmed that the steering/handling deviation was precipitated by the drive wheels. The load and trailer did not initiate the deviation as the trailer remained upright after the deviation. This was confirmed by the fact that there were no heavy tyre outside edge scuff marks corresponding to the trailer tri-axle wheels. Additionally, he says that at or about the 19 metre mark away from final resting place, the prime mover moved across the centreline onto its incorrect side. "As it crossed the road the changing road camber would have further disturbed the vehicle's steering/handling including further disturbance of bogie suspension wheel loads and chassis' reaction". The truck basically continued on in a straight line and hit the guardrail at approximately 45km/h and at a point approximately 13.5 metres from final resting place.
134 The relevant section of the report continued as follows:
"On impacting the guard rail recovery was no longer possible and the situation became an accident. The vehicle combination continued through and past the Armco guard rail removing a substantial section of it. The actual deviated motion terminated on contacting a eucalyptus tree at the front right-hand side of the vehicle. The impact with the tree occurred at less than 21km/h. The sudden deceleration of the prime mover cause the trailer to roll over and/or partially rest upon the guardrail and the load to totally dislodge."
135 In his evidence-in-chief, Dr McLean explained that the facts upon which he based his conclusion that the nearside drive wheels left the pavement, were those evident from the vehicle log event and the graph based on the actual distances between axle groups and "The known time lags between the events occurring when the steer tyre went through the apex of the corner, the bogie and then the time delay because of the greater distance ... to the tri-axle." He was asked to explain how he had reached the conclusion that the trailer did not initiate the deviation as it remained upright after the handling deviation. He said that one unusual feature of this accident was that there were no heavy tyre scuff marks from the tri-axle were it to be rolling over. If it did rollover then he would expect a series of three marks on the off side or incorrect side of the roadway.
136 One of the matters focussed on in cross-examination was the movements of the truck once it had crossed onto its incorrect side, up until the point at which it struck the tree. Involved in this discussion was consideration of damage to the Armco railing as shown in the photographs. Dr McLean said that he had looked at photographs of the damage to the prime mover, and said that he was very confident the truck was "near upright" when it struck the tree. He said though, that the whole truck would have been at an angle because of its progress down the embankment. It would have been leaning over, but it was not his understanding that it was on its side when it collided with the tree.
137 Dr McLean confirmed that, in his opinion, the truck was "more or less still upright when it left the roadway". Discussion then turned to the nature of the damage to the guardrail. The photographs show a flattened section of the guardrail over a short distance before the opening for the track which I have earlier described. The actual length of railing involved is difficult to estimate, but it involves three sections with four posts having been flattened and the railing obviously squashed. The particular point of focus was that the flattened railing itself is sitting to the roadside of the posts, with the posts also showing signs of being pushed in the direction of the truck's travel. The particular point is that the posts were on the river side of the flattened railing, not the road side.
138 Dr McLean suggested that the contact was at a relatively low speed with the final rollover then occurring and damage done by the logs falling off the truck in and around the guardrail where it is shown as flattened. It was suggested that the damage to the guardrail was caused by the trailer moving forward and rolling on to it. Dr McLean said that there had essentially been vertical force onto the guardrail indicating that the load on the back bunk of the trailer had rolled onto the guardrail in an essentially vertical manner with very minimal forwards force. This point of difference was pursued. For the purpose of the pursuit, reference was made to the two reports prepared by Dr Prem. Dr McLean was asked whether he had read them; he said that he had not seen them. He said that he had not been asked to give any consideration at all to the theories advanced by Dr Prem as to how the accident might have happened, and had not been told what those theories were. He agreed that he did not "even know anything at all about what Dr Prem says about this accident". The questioning continued as follows:
"You see, Dr Prem's explanation for this accident, if you have both of those large photographs in front of you - ......Yes.
Is this. That as the vehicle came into and started to negotiate that corner, the trailer has begun to tip, roll. That is the tri-axle - left hand tri-axle wheels have begun to lift and as its continued around the corner, that roll has progressed to the point where the trailer has reached the point of no return by which time the inside left hand drive wheels on the prime mover have then also started to lift. Eventually we're still progressing along the roadway. Now I ask you to follow very carefully what I'm about to say. The trailer rolls and falls onto the Armco as shown in exhibit P18(b), by which time the drive wheels - inside drive wheels are off the road and the mark that we see in the photograph - this mark on P18(a) and P18(b), starts to be created by the lightly loaded left hand steer wheel. The end of that mark, which is seen as the darkest part of the mark, in photograph P18(a) is the final point where the left hand steer wheel also lifts off the road as the whole rig finally rolls over. It continues on along that path keeping in mind that the left hand steer wheel where my thumb is on the darkest part of the mark in P18(a). So the other side of the prime mover is probably off the road there, can you see that? The one I'm showing you?......Yes.
And it continues on and comes into contact with the tree. Already, the whole rig by then is on its side. Now that's how Dr Prems has described this accident occurring. What do you say about that theory?......Incorrect.
You reject, do you not, the notion that this mark that looks like a skid mark, and we'll call it that for the moment, on P18(a) has anything to do with this accident?......Sorry?
You say you don't think this mark -......I'm confident that that mark has no relation to this accident, yes.
You're confident that mark has no relationship to this accident?......That is correct."
139 The point was later revived. Dr McLean confirmed that in his view, the prime mover would have been leaning over as it went down the bank, and that it impacted with a tree at about 21km/h; the trailer then rolling over or partially resting on the guardrail. He continued:
"When that truck hit the tree and in a rolled over position you can see there's kinematic coupling here between the turntable of the truck and prime mover so that would have bumped it and kicked it around and the momentum is still here so it tended to jack-knife a bit and then that would have gone on, over the guard rail, but the truck is still, you know, bumped into the tree and in that motion there was the damage that was done to the posts of the guard rail. If that had been rolling over, the guard rails proper would have been on the outside, not on the road side of the post to the guard rail but the logs landed on the western section, the damaged section ...".
140 Dr McLean said that it was correct that the trailer did not roll over and cause the damage until the truck hit the tree, but that the prime mover itself had just "clipped" part of the railing at the end, as it went past. These conclusions, he said, were drawn from the vehicle event report and the photographs. As to the two instances of "handling deviation", in which the nearside drive wheels left the roadway, Dr McLean agreed that the corollary was that there was more loading on the off side wheels, with the vehicle rolling. After some prevarication, he ultimately agreed that the phenomenon of the nearside drive wheels becoming less loaded for two periods of time "could simply mean that the truck was being pushed hard into the corners".
141 In his first report, Dr McLean said that the photographs of the curve indicate that the road camber was extremely favourable, with infill inside the fog line of the curve's apex contributing greatly to safe negotiation of speeds. He gave evidence about an investigation into complaints of high vibrations involving a number of vehicles. As a consequence, he travelled in coal trucks. He noticed that the drivers would negotiate corners with speed advisory signs of 55km/h, at speeds of 75 - 80km/h. He said: "I then realised what they're doing subconsciously. They simply applied the lock gradually, pick the apex and then decrease the lock slowly". He said that he "did the mathematics" of all of this which resulted in a paper which he presented to a conference. The effect of this evidence was that this experience accorded with his observations made of log trucks driving through the Plenty bends shortly before the trial started. He said they were able to effectively maintain one line through to corners without crossing over the centreline and just missing the near side edge of the roadway. Dr McLean did not make specific reference to speed, but I infer from the evidence that his assessment of what he had seen suggested speeds in excess of the speed advisory limit. Apart from the questioning as to an explanation for the two handling deviations which I have noted above, there was no cross-examination as to this aspect.
142 The plaintiff objected to the admission of parts of Dr Prem's reports. The evidence was taken provisionally, and cross-examination directed to the admissibility issues. I heard submissions before the close of the defendant's case and ruled that the parts of the report objected to should be admitted. I said that I would later give my reasons in my final reasons for judgment, and I now do so.
143 Dr Prem's evidence was contained in two reports and a DVD of three dimensional animated imaging showing a representation of the rollover. His opinion was based on two types of modelling. The first was described as "numerical" modelling. That involves breaking down the particular mechanical system into separate parts comprising, for example, masses. Those masses will represent various parts of the vehicle such as the chassis, suspension members and payload. The fixed and moving parts and other connecting parts such as tyres are given a numerical value, as are sets of conditions imposed on the basic "system". Each operative element is assigned a numerical value that relates to its actual physical properties. This results in a virtual version of the vehicle in a mathematical model and its behaviour under changing conditions can be determined. It is a process of spreadsheet calculation based on the laws of physics.
144 The second type of modelling was "whole of vehicle modelling" using what is known as the ADAMS software (Automatic Dynamic Analysis of Mechanical Systems). The software can be used to produce animated modelling of vehicular behaviour. Dr Prem said that the results from the whole of vehicle modelling match those from numerical modelling. The graphics were produced with the aid of what was called MSD Atruck Toolbox. This was not explained. The ADAMS software requires input of the same sort of datasets but the software program produces the graphic outcome of the calculation process. In this case, of course, the modelling was shown in the DVD. This was sought to be tendered. Dr Prem said that the DVD modelling contained some additional features to that which was reflected in his two reports, and that it confirmed the conclusions made in the two reports.
145 The objection related to the ADAMS modelling, not to any conclusions which Dr Prem might have drawn from the numerical modelling. The part of the first report which was objected to was in the following terms:
"Simulations were performed ... and the rollover stability of the logging truck was estimated. Logging truck SRT was estimated to be 0.314G. Further, Fig H3 shows the modelled logging truck at the point of roll instability. This shows that wheel lift occurs first semi-trailer axle group, which has higher roll stiffness than the drive group and is able to support a larger proportion of the overturning moment. This result is consistent with rollover scenarios of prime mover and semi-trailer combinations as revealed in full-scale testing and numerical modelling of both high and low CG vehicles, and with the descriptions presented earlier in this report."
146 Figure H3 was a still image taken from the DVD showing in illustrated format the modelled logging truck at the point of roll instability, or when it was "just about to rollover". It shows the entirety of the nearside trailer wheels off the ground. The last item of evidence objected to, apart from the DVD itself, was Figure 15 in the second report which was a similar type of image. It shows the final stages of wheel-lift sequence from the numerical modelling. It also has the nearside trailer wheels off the ground and purports to show the nearside steer tyre as "the last tyre to lift-off". A discrete objection to an aspect of the DVD was also made. This part purported to show the previous model but with an increased ride height of the suspension on the drive axles raised by 1.5 inches.
147 The plaintiff submitted that, as confirmed in cross-examination, the reports did not disclose the numerical values used in the modelling. It is not clear what particular aspects of these features required what values, but Dr Prem agreed that in relation to, for instance, the Hendrickson suspension and the tyres, the mechanical properties assigned to the model were based on information received from the manufacturer. Dr Prem was taken to a joint publication of his - Comparison of Modelling Systems for Performance-Based Assessments of Heavy Vehicles. This document had a detailed tabulation of values for a range of matters which, I infer, are needed to properly create the modelling. Dr Prem agreed that in relation to about six or so identified examples that the figure he actually used in this case was not disclosed in his reports. As to some of these examples, the source was identified as being for example, apart from manufacturers' specifications, generic figures based on studies or general experience.
148 The plaintiff pointed to the fact that neither in Dr Prem's evidence-in-chief, nor the point having been pursued at some length in cross-examination, did it seek to prove any of these values in re-examination. It was said that the numerical values used for the modelling were of critical importance in the outcome of the modelling. Both of Dr Prem's reports contain similar statements as to the assumptions and data upon which the analyses were based. Relevantly, they were the technical specifications for the prime mover and mechanical properties of a number of key components, as obtained from the vehicle and component manufacturers. As to the semi trailer, specifications, mainly key dimensions, "were based on the information presented by Mr Lambert in his first report. The mechanical properties of key components (suspensions) were based on information available in the public domain. Payload mass properties were developed from first principles". It was further stated that the analysis of rollover stability relied upon developments of that information.
149 I have already noted that the objection was not to Dr Prem expressing an opinion based on his numerical modelling. The objection was taken to the evidence in the form of the animated modelling. The objection to admissibility was based on the failure, as it was asserted, to identify and prove "assumed" or "accepted" facts. Relying on what Heydon JA said in the well-known passage from Makita (Australia) Pty Ltd v Sprowles [2001] NSWCA 305; (2001) 52 NSWLR 705 at [85], it was argued that as these matters were not "made explicit it is not possible to be sure whether the opinion is based wholly or substantially on the expert's specialised knowledge", as required by the Evidence Act, s79, and that: "If the court cannot be sure of that, the evidence is strictly speaking not admissible, and, so far as it is admissible, of diminished weight."
150 It was further submitted that if admissible, I should refuse to admit it, on the basis that its probative value was substantially outweighed by the danger of unfair prejudice. The asserted unfair prejudice was the plaintiff's inability to test the results obtained, and the fact that no critical evaluation of the opinion could be carried out. The plaintiff submitted that the process underlying the graphics themselves were "where the opinion resides", rather than being illustrations of it. For the defendant, it was accepted that specific and particular values were not disclosed, but submitted that the thrust or substance of the opinion was contained elsewhere than in the evidence objected to. It was submitted that further, or in any event, the issue was one of weight rather than admissibility.
151 In Sydneywide Distributors Pty Ltd v Red Bull Australia Pty Ltd [2002] FCAFC 157, Branson J at [7], expressed the view that the approach of Heydon JA in the Makita case was to be understood "as a counsel of perfection". Her Honour said that a reading of the reasons for judgment of Heydon JA as a whole, revealed that his Honour "recognised that in the context of an actual trial, the issue of the admissibility of evidence tendered as expert opinion evidence may not be able to be addressed in the way outlined ... ". At [16], her Honour said:
"Further, the requirement that an expert opinion be wholly or substantially based on the witness's specialised knowledge is not, in my view, intended to require a trial judge to give meticulous consideration, before ruling on the admissibility of the evidence of the opinion, to whether the facts on which the opinion is based form a proper (in the sense of logically or scientifically or intellectually proper) base for the opinion. Were the position otherwise the smooth running of trials involving expert evidence could be expected to be interrupted by the need to explore in detail, in the context of admissibility, matters more properly considered at the end of the trial in the context of the weight to be attributed to the evidence. It is sufficient for admissibility, in my view, that the trial judge is satisfied on the balance of probabilities on the evidence and other material then before the judge that the expert has drawn his or her opinion from known or assumed facts by reference wholly or substantially to his or her specialised knowledge."
152 In the same case, Weinberg and Dowsett JJ said at [87]:
"The use of the phrase 'strictly speaking' in the last sentence should not be overlooked. It may well be correct to say that such evidence is not strictly admissible unless it is shown to have all of the qualities discussed by Heydon JA [in Makita's case]. However many of those qualities involve questions of degree, requiring the exercise of judgment. For this reason it would be very rare indeed for a court at first instance to reach a decision as to whether tendered expert evidence satisfied all of his Honour's requirements before receiving it as evidence in the proceedings. More commonly, once the witness's claim to expertise is made out and the relevance and admissibility of opinion evidence demonstrated, such evidence is received. The various qualities described by Heydon JA are then assessed in the course of determining the weight to be given to the evidence. There will be cases in which it would be technically correct to rule, at the end of the trial, that the evidence in question was not admissible because it lacked one or other of those qualities, but there would be little utility in so doing. It would probably lead to further difficulties in the appellate process."
153 A fair reading of Dr Prem's first report bears out his approach as outlined in his evidence. After setting out a number of factual matters and a critical appraisal of Mr Lambert's report, he proceeds to a "preliminary analysis" of the rollover crash. After looking at the "road and warning signs", the truck speed as shown by the vehicle event log, and features of horizontal curvature and lateral acceleration, he deals with "Numerical Model of Logging Truck". In a section entitled "Verification of Numerical Model", Dr Prem observes that in the absence of the truck itself, it is not possible to verify the performance of the numerical model against that of the actual vehicle through physical testing. He then goes on to describe the simulations carried out in accordance with the rules. These rules come from Rules for Assessment of Potential PBS Vehicles - a publication of the National Road Transport Commission in 2005. The second report contains more detailed analyses of matters contained in the first report.
154 I formed the view that it was not correct to say that Dr Prem's opinion resided in the parts of the evidence objected to. It seemed to me that his approach was a co-ordinated one involving numerical modelling with the datasets then being applied to the whole of vehicle modelling by way of the software program. This was to verify the numerical modelling, the end stage of which was the DVD model which was a graphic representation of an outcome which he could have, and did in reports, describe in words. I took the view that there were insufficient deficiencies in the disclosure of the values used to make the material inadmissible as being irrelevant pursuant to the Evidence Act, s55. Further, I did not think that any deficiencies were of sufficient proportions to prevent me from concluding that the opinion was wholly or substantially based on Dr Prem's knowledge, within the meaning of s79; see Neowarra v Western Australia [2003] FCA 1399; (2003) 205 ALR 145 at [16] - [27], and Gambro Motel Pty Ltd v Fresenius Medical Care Australia Pty Ltd [2007] FCA 1828; (2007) 245 ALR 15 at [44]. I took the view that the issue was correctly described as one of the weight to be attributed to the evidence objected to rather than its admissibility.
155 In Cadbury Schweppes Pty Ltd v Darrell Lea Chocolate Shops Pty Ltd [2007] FCAFC 70; (2007) 159 FCR 397, the court at [108] - [109] said that:
"It should not be for a cross-examiner to endeavour to elicit the facts or assumptions upon which an opinion is expressed, and it would be unfair to leave such matters to the cross-examiner. Except in a straightforward, uncomplicated case, where the facts are admitted or otherwise readily identified, opinion evidence would normally be rejected under s135 if the facts or assumptions upon which the opinion is based are not expressly stated ... The process of inference or reasoning that leads to conclusions ought to be stated or revealed in a way that enables the conclusions to be tested and a judgment to be made about their reliability and the weight that should be given to them. If not, the opinion evidence would normally be rejected under s135."
1">156 In this case however, as I have noted, it seemed fairly clear to me that the substance of the ultimate opinion as to the cause of the rollover, was not contained, even to a large extent, in the evidence which was the subject of the objection. That evidence, taken on its own, might not have the significant probative value, but in those circumstances, neither could it be said that it was unfairly prejudicial.
157 Dr Prem's view is, of course, that excessive speed was the sole cause of the accident. I should record at the outset, that his modelling is based on an assumption of a "correctly loaded" truck, and beyond an allowance for a maximum load height of 2.4 metres, his evidence does not take into account or address the issue of possible overloading of the front bunk. In his first report, one of the principal issues considered was "Horizontal Curvature and Lateral Acceleration". This was based on available maps. The bends were identified, together with the location of the associated points of maximum curvature; that is, minimum radius. The bend having the highest curvature is the plaintiff's bend 2. Bend 6, where the accident occurred, has the second highest curvature of the series of bends. Dr Prem goes on to develop a "lateral acceleration profile". This is explained as follows:
"A vehicle travelling along a curved path is subjected to an outward force in an overturning moment that is proportional to the lateral (or sideways) acceleration experienced by the vehicle. Rollover occurs when the lateral acceleration that causes the overturning moment is sufficient to exceed the vehicle's rollover limit."
158 Dr Prem then sets out the basic equation for lateral acceleration in a steady turn. He says that this shows "that lateral acceleration is highly sensitive to speed, and it is inversely proportional to the radius of the turn; doubling speed leads to a four-fold increase in lateral acceleration whereas halving the turn radius only doubles the lateral acceleration". In evidence, he said that as long as the SRT of a vehicle is higher than the lateral acceleration it will not roll over, but that once the lateral acceleration exceeds the SRT, there is a high roll over risk.
159 Three separate speed scenarios were adopted. They were a constant speed of 55km/h, consistent with the speed advisory speed; a constant speed of 60km/h which was asserted to be the speed the plaintiff determined as a safe speed for the first bend, and the actual speed as recorded in the vehicle event log "synchronised to the curvature profile". The resultant calculations using the actual speed recording give rise to the conclusion that even if the vehicle was safely to negotiate bend 2, the risk of rollover would still be present and actually higher on bend 6. The degree of lateral acceleration in relation to bend 6 was shown as 0.340, a 124 per cent increase over bend 2. From that point, to assess the significance of the lateral acceleration levels, the rollover stability of a "correctly loaded logging truck" was estimated. This is dealt with in the next section of the report, entitled "Numerical Model of Logging Truck", a section of the report to which I have previously made reference.
160 The numerical modelling commenced with an empty logging truck consistent with the geometrical layouts and mass distributions as shown in one of the appendices. This drawing shows the dimensions of the assumed layout and axle group loads. Payload shape and mass properties of a typical "good" load were developed from "first principles" based on information from certain stated sources. Dr Prem says that these are consistent with a logging vehicle operating at the maximum allowed gross mass and the maximum allowed group loads. The basic shape of the assumed payload and the centre of gravity height is shown in a further diagram. Dr Prem continues in that "it is important to note that in this configuration the vehicle is both correctly loaded, the axle group loads are at their legal maximum and the payload COG height is also consistent with that described in [Mr Lambert's] report for a correctly loaded logging truck".
161 The further diagram referred to shows axle group loads for the steer axle, the drive axles and the tri-axle group as 6 tonnes, 16 tonnes and 20 tonnes respectively. In his evidence, Dr Prem said that he assumed that the vehicle was loaded to the maximum legal load and that as to the distribution of the load, "the axle loads were correct". He explained that when he used the expression "correctly loaded", he was referring to the maximum legal axle loads stated by him. In relation to the payload, he assumed that it was a rectangular prism with the centre of gravity at its centre.
162 In the first report, Dr Prem goes on to deal with the verification of the numerical model, and the estimation of static rollover threshold, referring to the simulations in the passage which was the subject of objection and which I have set out above. It will be recalled that the SRT of the plaintiff's truck was estimated at 0.314g. Dr Prem then turns to an analysis of factors which led to the rollover. He says that the analysis of the rollover stability of a correctly loaded log truck is "used to assess the significance of the lateral acceleration levels determined from consideration of the interaction between path curvature and speed ...". Using the speeds of 55km/h, 60km/h and actual speed profile, lateral acceleration figures of 0.227, 0.267 and 0.274 are given in respect of bend 2, whilst the respective figures for bend 6 are 0.193, 0.228 and 0.340. The latter figure represents 108 per cent of the SRT of 0.314.
163 Dr Prem goes on to say that this safety margin of 8 per cent "ignores the stabilising influence of the pavement superelevation". Superelevation, or crossfall, is the degree of slope from one side of the road to the other. On curved sections of the road, the slope is towards the inner radius. Taking into account a typical crossfall (the actual figures were not available to him at the time) this would reduce the amount by which the safety margin had been exceeded on bend 6 from 8 per cent to a value in the range 1 to 5 per cent. This, it is said, shows that on bend 6 at the recorded speed of travel, the truck achieved and sustained a lateral acceleration level exceeding that required to cause the vehicle to roll over. "This indicates clearly that the truck was simply going too fast to negotiate the bend safely. ... The vehicle speed on that bend was more than 15km/h faster than the posted advisory speed of 55km/h." The conclusion from this "preliminary analysis" was "that excessive speed was the primary reason for the rollover crash."
164 The second report covers much of the same ground, but primarily "considers new and compelling evidence from the analysis of road geometry". Additionally, some further information as to the details of the prime mover are said to provide clarity in relation to a number of issues. "The new information disclosed as part of this report, together with the further investigations provide new insights and a clear picture of the circumstances and factors that led to the log truck rollover."
165 This report contains additional discussion as to the log truck and its rollover stability. As to the subject-matter of physical dimensions, axle group loads and payload, three key points of difference from the assumptions made in the first report were noted. The drive axle group spread was increased to accord with the latest advice from Kenworth. The drive axle group load for the laden vehicle was increased from 16 tonnes to 16.5 tonnes "consistent with a maximum permitted axle group load under the regulations prevailing at the time". Precisely how this figure was arrived at was not made clear. Lastly, two load configurations were considered; the first was with a front bunk load height of 2.1 metres as in the previous report, but with a second configuration with the front bunk load height at 2.4 metres. These were said to represent average and maximum loads.
166 With those front bunk load assumptions, the SRT values are given as 0.309 (as distinct from 0.314), and 0.294 with the payload height at 2.4m. These SRT values are said to be more consistent with Mr Lambert's views, and "overlap with Australian fleet vehicles that have the lowest rollover stability, ... That is, the log truck that rolled over should be considered as having a low to very-low rollover stability, a fact that would be well-known to skilled and experienced log truck drivers." In cross-examination, Dr Prem agreed that this fact would equally have been known by the drivers' employers. He also agreed that in 1996 the logging industry would have known that the greater the speed, the greater the chance of loss of control when cornering, and that the higher the centre of gravity, the greater the chance of a rollover. As it was later clarified, the true point is that for a given track, the higher the centre of gravity, the greater the chance of a roll over accident. Further still, he agreed with the proposition that even moderate reductions in centre of gravity height lead to substantial improvement in rollover stability.
167 As I earlier indicated, it is more convenient to deal at this point, with some of Mr Lambert's evidence. In his second report he notes that accuracy in determining curvatures may be in the order of + - 10 per cent, which may have an appreciable effect on the calculation of lateral acceleration given that the radius of the turn is a factor in the equation. Moving on from that, he deals with the subject of "cutting corners" by a skilled driver. Such a driver, he says, would use the lane width to reduce the minimum curve radius by:
•
starting with the outer side of the vehicle with the outer edge of the lane at the beginning of the curve,
•
having the inner edge of his vehicle at the inner edge of the lane or pavement at the middle of the curve; and
•
finishing with the outer side of his vehicle at the outer edge of the lane at the end of the curve.
168 On the basis of his measurements of the particular corner, he says that if the truck had followed the centre line, it would have been following a radius of 128.4 metres, but by using the "whole pavement width" the driver could increase the radius to 152.5 metres (18.8 per cent) and by using the lane width only he can increase the radius to 146 metres (13.7 per cent). By means of a table with comparative speeds, measurements and corrections for superelevation, Mr Lambert arrives at a value for lateral acceleration at 72km/h of 0.178g where the radius of the curve is corrected for error and measurement and "corner cutting". In his third report, he undertakes a similar exercise, but using a "best fit" curve of 89 metres, and curvatures of 122.5 metres if cutting the corner within the lane, and 135.0 metres if cutting the corner using the road shoulder. At a speed of 72km/h and with an average crossfall of 8.72 per cent, the resultant lateral acceleration figures are respectively 0.371g, 0.246g and 0.215g.
169 The second report contains considerable discussion of the road geometry, and in particular a verification of the horizontal curvature and the crossfall. Dr Prem concludes that the maximum accorded value of crossfall on bend 6 is 10.6 per cent which occurs at the tightest part of the curve. He goes on to assert that the horizontal curvature profile shows that the relevant curves were significantly tighter than estimated in his first report. The radius of bend 6 is shown as between 87.7 to 92.6m and the crossfall as between 10.0 to 10.6 per cent.
170 From that point, consideration is given to lateral acceleration levels and rollover risk, included in which is discussion as to the speed profile and the assumed steer path. For the time being, a steer path in the centre of the southbound lane is assumed. Dr Prem gives the equation for lateral acceleration in a steady turn, but including the influence of superelevation or crossfall. The equation is basically the same as for lateral acceleration as such, but the value for superelevation operates as a deduction at the final point of calculation. The value ascribed to superelevation is expressed as a decimal representing the percentage; eg, 10.6 per cent crossfall results in a value in the equation of 0.106. The introduction of superelevation to the equation adjusts the lateral acceleration figure by a reduction by the relevant percentage.
171 The report then moves to a tabulation of the rollover risk for the three speed scenarios, similar to that which I have earlier set out, but taking into account the updated horizontal curvature information. On bend 6, the figures are 0.180, 0.230 and 0.385 for the speeds of 55km/h, 60km/h, and the actual speed profile. The latter figure is between 124.3 per cent and 140.6 per cent of the SRT, the range being attributable to the two different front bunk load assumptions. Dr Prem concludes that there is no doubt rollover would occur at bend 6, "where the lateral acceleration level exceeds the truck's rollover threshold by between 24.3 % to 40.6 %."
172 However, I should immediately note that, as was amplified in cross-examination and as Dr Prem agreed, the lateral acceleration figures of 0.340 and 0.385 for bend 6 given in the first and second reports, make no allowance for superelevation. He agreed that factoring in a 10.6 per cent figure to the value of 0.340, gives the result of 0.234. Obviously, 0.385 becomes 0.279. This needs to be compared to the estimated SRT of the truck as 0.314g. The cross-examination was as follows:
"Why is it that you assumed a reading - or sorry, that you calculated a reading for lateral acceleration without taking into account superelevation?.............There is a discussion on superelevation in this - in this report.
Yes, there is a discussion, but you ignored it, Doctor. I want to put to you that you ignored it because it didn't suit your theory to include it?......No, I was using the best information I had at the time.
That there was no superelevation?......No, there was superelevation.
Well why didn't you take it into account, Doctor?......That was a shortcoming of this report.
I put it to you, Doctor, the only reason you excluded it was because it did not suit your theory, that is that lateral acceleration exceed static rollover threshold, ie speed was the cause, what do you say to that?......I don't agree."
173 What is then considered in the second report is Mr Lambert's views on "cutting corners". Dr Prem says that there are "fundamental and important issues" which Mr Lambert failed to consider. These issues relate to calculations of the radius of the curve, the movements of the truck necessary to achieve the corner cutting, and the lateral acceleration values produced. He says that in order to decrease the horizontal curvature of bend 6 and attempt to contain lateral acceleration levels, the driver must travel outside his lane and use more road space than is legally available to him. In particular, he says that when the truck had its offside steer wheel on the centre line, and following a curve with an outside radius of 89 metres, the lateral acceleration is 0.378g, with an average superelevation of 9.75 per cent. In order to cross to the other extremity of the roadway a change of heading of 18.5 degrees is required over a distance of 28.4 metres. At 72km/h, the average lateral acceleration is 0.377g. To return to the other extremity of the lane, a heading change of 14.9 degrees is required over the length of the vehicle being 17.8 metres, which gives a 0.509g which is 60 per cent above the truck's rollover limit of 0.309g.
174 By looking at the horizontal curvature in diagrammatic and pictorial form, Dr Prem concluded "that it was not possible for the log truck to keep within its lane at the speed that it was travelling and not rollover." He said in evidence that if the vehicle was doing the indicated speed and staying within its lane, the lateral acceleration would be about 0.4g. In fact, if it had kept within its lane, the calculations indicate that rollover would have occurred on the previous bend, or even earlier on bend 2. He reports: "However rollover occurred on bend 6 and, therefore, it can be concluded, without any doubt, that the driver did not keep the vehicle within its lane on the previous tight curve, bend 6."
175 Dr Prem then addresses the question of whether or not the truck was able to negotiate the series of bends at the recorded speeds under the most favourable turn conditions. The most favourable "cutting-corner-steer strategy" that will give the driver the best chance of successfully negotiating the curves, and in particular the curve where the rollover occurred, is shown by him in diagrammatic sketches superimposed on Google Earth maps. These show the truck wholly on its incorrect side of the road in the straight section approaching the corner, then wholly on its correct side of the road through the apex and crossing onto its incorrect side of the road just before rollover.
176 Dr Prem says that there is sufficient information from the analysis presented to reconstruct the rollover crash with a reasonable degree of confidence. A probable scenario is offered. Again this is illustrated by sketches superimposed on actual photographic maps. He says:
"The overview scene shows the vehicle taking a wide line through the curve ... This has been assumed because the analysis concluded the speed was too high for the driver to stay within his lane, and therefore a wide line in cutting-corner steer-path appears to be the only way to attempt to negotiate this corner at high-speed (70km/h) in a fully-loaded log truck."
177 When cross-examined about the "cutting-corner steer-path", Dr Prem agreed that in reaching his conclusions, he had not assumed that the driver had effectively used the whole of the available lane in the way in which the plaintiff had described his negotiation of the bends. Dr Prem said that there were a number of factors, including tyre flexibility, which influenced the way a trailer tracked. His view was that if a driver was doing as the plaintiff said, then the trailer would be on or crossing the centre line.
178 I should also mention part of this report which deals with the suggested cause for the skid mark. Dr Prem said he assumed the driver's reaction to the rollover situation was delayed and occurred when the rollover was well advanced. "Once the driver realised something was happening and the vehicle was running wide, his instinctive reaction would be most likely to brake and then steer to the left. It is assumed that the braking and steer action occurred before the front left steer tyre lifted." He goes on to explain that this tyre would be the last to lift off, and being lightly loaded it would lock easily (I assume on braking) and skid to leave a light scuff mark on the road. The point is that he assumed the plaintiff steered to the left. This was not the plaintiff's unchallenged evidence. Dr Prem also conceded the possibility that the skid mark had nothing to do with this accident.
179 The question of the skid mark raises Dr Prem's theory as to the behaviour of the truck in the rollover. In his first report, after analysis of a photograph of the skid mark, he concluded from various distances, that at some stage during the rollover process up until the vehicle came to rest, the pitch angle orientation of the prime mover with respect to the semi-trailer was 90 degrees, which physically lead to separation at the turntable between the two vehicle units. In his evidence he described the process of the front left steer tyre lifting off, at which stage the whole of the vehicle is well into the final stages of the rollover. He said that at that point the vehicle would roll onto its side, and slide down the road on its side but going through a rotational turn as well. "So what I am suggesting is that once the vehicle is on its side it's now rotating and sliding towards that tree ... and it impacts with the tree when it's on its side." In his second report, by use of the sketch overlays, Dr Prem demonstrates that the vehicle is relatively upright at the commencement of the skid mark but totally on its side with all components of the truck in line when it has come to rest against the tree. I may be misunderstanding the thrust of his evidence, but doing my best, I am unable to reconcile these aspects of his evidence.
180 Finally, I note Dr Prem's ultimate conclusions set out in his second report. They are:
•
rollover was highly probable for a correctly loaded log truck operating within normal load parameters and proper suspension settings travelling at the speeds recorded.
•
it was physically not possible to negotiate the curve in a correctly fully loaded log truck travelling at 72km/h and stay within the designated lane, without precipitating rollover.
•
it appears physically possible to negotiate the curve at 72km/h in a correctly loaded vehicle which has an SRT value greater than 0.30g using the entire road space, but this carries an extremely high risk of rollover and very little margin for error.
•
the precise location in the turn at which the point of rolling stability was reached is not known, but given the vehicle's proximity to rollover, it would take very little to precipitate it.
•
the driver used the entire road space (both lanes of the two lane road) to negotiate the curve and in moving from one lane to the other crossed continuous double white lines.
•
the most likely cause of the crash was excessive speed.
The causes of the rollover and whether the defendant was negligent
181 I fear that I have been overly long in my summary of the relevant expert evidence, but I think it was necessary in order to understand the parameters of the debate, and in deference to the arguments which were put. As a starting point for what follows, I find that speed, centre of gravity issues, and the correlation with the risk of a rollover crash were known in the logging industry in 1996. I also find that the low to very low rollover stability of log trucks was a phenomenon familiar to those who operated them in 1996. These statements are supported by Dr Prem and it is of note that respect for the laws of nature to do with forces, momentum and the centre of gravity was set out as a requirement in the defendant's "Ten Commandments" for drivers, to which I have referred. Mr Lambert said, and I accept, that of the factors influencing rollover, the most critical are the centre of mass and the weight of the load. This was particularly so with a product such as logs. At the same time, Mr Lambert accepted that a driver should allow for a proper safety margin when selecting a curve speed.
182 An issue which is dealt with in the TERNZ July 2005 report is that of curve speed selection. The following observations in the report cover a number of factors relevant both to the cause of the rollover, and the question of the likelihood of a risk of injury materialising:
"The standard method for determining the advisory speed is based on a scale that reflects passenger car comfort, not truck safety. For lower advisory speeds (35km/h and less) this speed can generate lateral accelerations of 0.3g or even higher. Thus, if a truck has relevantly low rollover stability ... it may rollover if driven around this curve at the advisory speed. At higher advisory speeds the lateral acceleration is less, but as a general principles trucks with low rollover stability should be driven round curves at speeds well below the advisory speed to maintain an adequate margin of safety ... Without an adequate margin of safety, small differences in load distribution, speed selection, line through the curve, road roughness and other factors can combine to take the vehicle from a situation where it can negotiate the curve safely to one where it rolls over. For an individual vehicle this occurs very rarely. It is not uncommon to hear of a driver saying words to the effect of 'I was going through the curve with the same load at the same speed as I always do and it just rolled over'. However, when these additional rare events are accumulated the end result is an increased rollover rate." [My emphasis]
183 There is a difference of opinion of course, between Mr Lambert and Dr McLean on the one part, and Dr Prem on the other, as to the basic scenario of the accident. The difference more starkly exists between Dr McLean's view of things as a "handling deviation" leading to loss of control in the collision with the tree, and Dr Prem's theory that rollover commenced at the rear of the trailer with the truck ending up on its side sliding towards the tree. Mr Lambert and Dr McLean focus on the suspension and load issues. Mr Lambert addresses speed in response to Dr Prem's opinion but in the context of considering the way in which the corner may have been negotiated by the plaintiff. On the other hand, Dr Prem focuses on the aspect of speed but does so on the assumption of a correctly loaded vehicle, and pays no regard to the suggestion of overloading on the front bunk. It may not be strictly necessary to determine the precise behaviour of the truck, save to the extent that the part of the vehicle from which the rollover is said to have initiated, is relevant to the competing theories.
184 The issue is whether or not the rollover commenced from the rear of the trailer. I found Dr McLean's analysis of the vehicle data, and his spontaneous rejection of Dr Prem's hypothesis with which he was not familiar, to be persuasive. I have already said that I am not able to gain much assistance from the photographs of the skid mark, nor from Mr Lambert's and Dr Prem's interpretation of them. The point that causes me difficulty with Dr Prem's theory in this respect is the nature of the damage to the Armco railing. I also find Dr McLean's view as to this to be persuasive. If the truck were on, or falling onto its side and veering off the roadway towards the tree, one would expect the railing to be pushed the other way, and indeed, some distance away from where it was. As things are shown in the photographs, most of the railing has been pushed forward and rotated anti-clockwise, as viewed from the direction in which the truck was travelling. There is some ostensible conflict between Dr Mclean's view, and the evidence of the plaintiff as to the position of the prime mover at impact, but the two are not irreconcilable. I accept the evidence of Mr Lambert and Dr Mclean that the initiation of the accident was from the drive axles.
185 The plaintiff's unchallenged evidence was that he was negotiating the curve at about the same speed and on the same line as he had done on many occasions in the past. In the nine or ten years at the frequency with which he negotiated the Plenty bends, quite a few thousand trips around this corner were involved. In this particular truck, loaded with logs, he would have driven around the bends several hundred times. There is no evidence that any incident occurred other than this one. In those many hundreds of trips, no doubt precisely the same speed, precisely the same load, and precisely the same line were not involved. That increases the probability that something quite untoward was operating on the night of the accident.
186 Having regard to my basic findings of fact as previously set out, and taking into account the further expert evidence, it is more likely than not that a combination of a number of factors operated to cause the accident. I am unable to say that any one factor on its own was the sole cause. Those factors, which I will examine in turn, are:
•
the inherent nature of the suspension system;
•
the adjustment of that system by the raising of the ride height on the day of the accident;
•
a higher centre of gravity, and hence a lower SRT than might reasonably have been expected, due to disproportionate loading as between the front bunk and the rear bunk, causing excessive loading on the drive axles;
•
the plaintiff's speed of driving.
187 The first two factors can be dealt with together. The starting point is the air suspension itself. It is clear that even with high flow HCVs, the nature of the system's operation results in instability when negotiating a series of left and right bends. In general travel, the vehicle leans to the left due to road camber, the consequent force operating to rotate the chassis frame in a clockwise direction, (when looking at it from the rear). In this series of bends, there is a slight left, followed by a sharp right, with the successive bends being left, right, left and left. As I have determined, it has not been shown that a reasonable employer in late 1995 ought to have known of the inherent design problems with the suspension. Whether or not the new valves which were fitted were the "high flow" ones referred to in the 2000 specifications, is not capable of being determined. But the evidence satisfies me that even with some form of high flow valves then available, the time delay of operation is such that counterproductive forces would have operated in this scenario. However, this needs to be considered in light of the adjustments to the ride height, to which I will now turn.
188 First, what I am satisfied of is that the increase in the ride height caused a corresponding increase in the height of the load on the front bunk above the drive axles. That exacerbated any high centre of gravity issue caused by the loading system. Second, the plaintiff's evidence is a little unclear but at the least, as I have found, on the night of the accident the prime mover did not have the veering or wandering characteristic. It was more rigid and did not require the steering input. I have found that the alteration in the ride height led to a greater degree of instability and that the adjustment of the ride height caused a lack of feedback to the plaintiff, to the extent that he was not able to readily discern the effect on the truck's handling, of any disproportionate load on the front bunk.
189 Thus, the elevation of the ride height of the suspension by Mr Pearton contributed to the increase in the centre of gravity of the load in question, and, looking at it objectively, resulted in a false sense of security. It operated as a disguise, in the sense that the plaintiff was not able to utilise the usual feedback which may well have alerted him to risk factors associated with the load. The alteration was carried out without the plaintiff's knowledge, and without any warning to him before he drove the truck on the night. It was done in the background of handling and stability problems known to Mr Pearton and apparently complained of by him to the defendant's management. In my judgment, in the circumstances the conduct was foolhardy. To make, without warning, such a change to the suspension of the vehicle leading to completely different handling, and to an elevation of the load height at the drive axles, was to create a risk of foreseeable injury. That is, it was foreseeable that such changes may cause an accident of some description, whilst the plaintiff was driving. It follows that Mr Pearton failed to exercise reasonable care in relation to foreseeable injury to the plaintiff. As argued by the plaintiff, the defendant is vicariously liable for Mr Pearton's actions.
190 This particular truck, correctly loaded and assuming an average load height of 2.1 metres, was estimated to have an SRT of 0.309, a figure at the upper end of the range for it, but still to be regarded as low. As is apparent, there seemed to be no disagreement with Dr Prem's assessment that the truck's SRT would ordinarily have been in the range of 0.273g to 0.309g. That proposition assumes a correctly loaded truck in the sense of a distribution of the weight of the load proportionate to the maximum legal axle loads. I am satisfied on the evidence, that even though I have not been able to find that the load was greater than 26.2 tonnes, a disproportionate amount of that load was borne on the front bunk. Using the figures which I have previously set out, this extra loading was somewhere in the order of two to four tonnes. This caused excessive load on the drive axles and created an overall higher centre of gravity of the load. In summary, the evidence supporting those conclusions is:
•
the evidence of the plaintiff, Mr Gill and Mr Brazendale as to the general operation of the particular load weighing system and the uncertainty of the end result with any particular load;
•
the evidence of the plaintiff as to the loading process as to the particular load, and the appearance of the front bunk having too much on it, even though the gauge at that stage read some 10kpa less than the nominated reading, with more logs put on the bunk even after that;
•
Mr Lambert's evidence that to get to the correct load, (legal axle loads plus tolerances), a pressure of 55kpa in relation to the front bunk load was the correct figure, and not 60kpa;
•
the plaintiff's evidence of his general observations of overloading on the front bunk, leading to his complaints that the veering problem stemmed from that;
•
what is evident from the series of photographs of the plaintiff's loaded truck prior to the accident. (Although there are some difficulties with Mr Lambert's analysis which I have pointed out, a simple inspection of these photographs bears out the thrust of all of his evidence as to this aspect. The amount of load in the front bunks can be measured against the height of the bolsters which are of consistent height along the length of the trailer. This evidence is also supported by Dr McLean's spontaneous evidence after inspecting the photographs in the trial);
•
Mr Lambert's evidence and calculations as to the range of possible overloading on this truck, arising from the use of the load measuring system.
191 It should be borne in mind that the trailer above the drive axles is 10 centimetres higher than its rear point. It should also be borne in mind that all of Dr Prem's modelling assumed a correctly loaded truck, implicit in which is a distribution of the load, proportionate with the maximum legal axle loads. Dr Prem also assumed that the centre of gravity of the total load was in the centre of a rectangular prism. A centre of gravity of the entire load is really the product of a combination of the centres of gravity of the loads on the front and rear bunks. An increase in the height of the centre of gravity of the front bunk leads to an increase in the overall centre of gravity. The overturning moment as described by Mr Lambert becomes significantly higher. This illustrated by Dr Prem's figure of 0.273g for a front bunk load height of 2.4 metres, as distinct from 0.309g at 2.1 metres. As Dr McLean pointed out, an increase in the height over the drive axles is an "adverse" situation. For those reasons I am satisfied that the front bunk was overloaded in the sense of that load being disproportionate to the load, and that this factor contributed to the accident.
192 The loading system on the plaintiff's truck was likely to lead to overloading on the front bunk, causing a higher centre of gravity than would otherwise be reasonably achievable. The risk of a rollover crash was therefore materially heightened. The magnitude of the risk in terms of its consequences was high, and the degree of probability of such an occurrence was also high, given the small margins for safe operations. The plaintiff's truck was the only one in the fleet equipped with the particular device. All others were fitted with the Lodec system. The defendant's reason, at least as given to the plaintiff, was that with the lighter tare weight of the truck, load carrying capacity would be adversely affected. No evidence was given on behalf of the defendant as to why the Lodec system could not reasonably have been fitted to the plaintiff's truck; McLean v Tedman [1984] HCA 60; (1984) 155 CLR 306 at 314. The defendant had in place the particular load weighing system which included the instruction as to its use, to load the front bunk until the reading was 60kpa. In my view, by so doing, the defendant failed to exercise reasonable care not to expose the plaintiff to a risk of foreseeable injury. It was in breach of its duty.
193 Just as with load, in bare theoretical terms speed will always be a factor in a rollover crash scenario. To state the obvious, a loaded stationary truck will not roll over. The question is whether it was excessive speed which caused or contributed to the accident. I approach this question on the basis that the plaintiff was travelling in the vicinity of 70 to 72km/h. I am satisfied on the evidence that leading up to the accident, the plaintiff was taking the line through the corner which he normally took and which he described in his evidence. His evidence as to this was not challenged and was consistent with the observations of Mr McGregor. It was also consistent with what Dr McLean described of his trips with coal truck drivers and it is supported by Mr Lambert's calculations which show that as a matter of physics, it is possible to negotiate bend 6 in the manner alleged at the relevant speed.
194 To accept Dr Prem's evidence that as the plaintiff went around the corner, he approached it from a point holding on his incorrect side of the roadway, is to reject the plaintiff's unchallenged evidence, supported as it is. It also means accepting that invariably, a correctly loaded truck would never make it around the corner at 72km/h if it were wholly within its proper lane.
195 It is neither possible nor necessary to settle on a speed at which the truck on this particular occasion could have safely negotiated the corner. But having said that, I am satisfied that in the circumstances which prevailed, the speed of 70 to 72km/h was excessive and that this excessive speed contributed to the accident. By prevailing circumstances I mean to refer to:
•
the plaintiff having been alerted to a potential risk in terms of the centre of gravity of the truck created by an unusual loading issue, and one perhaps even more unusual than previously encountered;
•
the fact that without warning to him, the truck suddenly began to sit up more solidly, not roll about as much, and had lost its veering and wandering characteristics;
•
the proposition that generally, a speed of 70 to 72km/h with a fully loaded log truck leaves little margin of safety.
196 The defendant's argument as to liability is that the sole cause of the rollover crash was the plaintiff's excessive speed. No response was made to that part of the plaintiff's case which was based on the assertion that his speed immediately before the crash, was the responsibility of the defendant by failing to train or instruct him having regard to the truck's actual or potential characteristics.
197 It is convenient to repeat the particular of negligence alleged. It is said that the defendant:
"Failed to train the plaintiff in driving the truck, in particular that by reason of the suspension system and/or overloading and/or unevenly distributed load he should enter corners cautiously at a reduced speed and that the truck may become destabilised after successive corners."
198 The unchallenged evidence is that the plaintiff, at an unidentified time before the accident, travelled through the Plenty bends with Mr Cox, the assistant transport manager. When loaded, he travelled through the Plenty bends at his usual speed. Mr Cox was sitting in a position where he could observe the speedometer. Mr Cox said nothing about his speed or manner of driving. The defendant was at all times in a position to check the plaintiff's speed and manner of driving, correlated to particular stretches of roadway, by reference to the daily Tripmaster data.
199 I have already noted the defendant's actual awareness of "the laws of nature to do with forces, momentum, and the centre of gravity". The plaintiff, and it would appear Mr Pearton, complained to the defendant about the truck's handling. The plaintiff blamed the handling difficulties on overloading caused by the loading system adopted. The employer's responsibility is not confined to unexpected and unusual dangers. In appropriate cases it extends to dangers which are obvious. In my view this was not a simple and obvious matter; see Raimondo v State of South Australia (1979) 23 ALR 513 per Mason J at 517. The defendant was aware of handling problems with the truck, at least until shortly before the accident. Some action had been taken, but Mr Pearton's intervention on the day, suggests the problems were continuing. The plaintiff had attributed the handling problems to overloading on the drive axles. The defendant had actual or constructive knowledge of centre of gravity issues correlated with high rollover risk. I have previously noted its attitude to the load measuring system. I think a reasonable employer would have taken steps to obviate or minimise the risk of injury caused by a driver travelling at an excessive speed in all of those circumstances. There is nothing to suggest that such training instruction was unduly onerous or impracticable for any reason. For those reasons, I find the defendant failed to take reasonable care, and was in breach of its duty in this respect also.
200 The plaintiff needs to establish that any one of the breaches of duty which I have identified, was a cause of, or materially contributed to his injury in the sense of being a contributing factor: March v E & MH Stramare Pty Ltd [1991] HCA 12; (1999) 171 CLR 506 at 514; Bennett v Minister of Community Welfare [1992] HCA 27; (1992) 176 CLR 408 at 420; Romeo v Conservation Commission (NT) (1988) 192 CLR 431 at 482 and Shorey v PT Ltd [2003] HCA 27; (2003) 77 ALJR 1104 at [41]. A contributing factor is material unless it is negligible: Bendix Mintex Pty Ltd v Barnes (1997) 42 NSWLR 307 at 345 and Western Australia v Watson [1990] WAR 248 at 286.
201 I have found that the defendant was in breach of its duty by failing to have in place a load measuring system which did not create a risk of injury by causing overloading on the front bunk, and in respect of the act of Mr Pearton in raising the suspension ride height. For the reasons which I have earlier given, I am positively satisfied that these breaches made material contributions to the plaintiff's injury. The only question that arises for discussion in this context is the breach of duty in relation to the failure to provide proper training. The plaintiff needs to establish that such training would have been effective; that is, he would have driven more cautiously and at a reduced speed. In cases involving an employer's duty to a worker, and at least where the issue is the failure to provide a particular piece of equipment or device, the determination of what the worker would have done, based on an assessment of the behaviour of a reasonable worker; McWilliams v Sir William Arrol & Co Ltd [1962] 3 All ER 623 per Lord Reid at 632 and Walfertan Processors Pty Ltd v Dever [2006] NSWCA 289 at [35] - [38].
202 In the general law of negligence, where questions arise as to the effectiveness of warnings (by sign or advice) the test is a subjective one The inquiry is what a particular plaintiff would have done; Chappel v Hart (1998) 195 CLR 232 at [32], [93]; Rosenberg v Percival [2001] HCA 18; (2001) 205 CLR 434 at [24]. In Fox v Leighton Contractors Pty Ltd [2008] NSWCA 23, this subjective test seems to have been adopted in the context of a duty of care alleged to be owed to an employee of an independent contractor; see per Basten JA at [57]. (Giles and McColl JJA agreed. The subsequent appeal to the High Court did not involve this point). In this type of case I would tend to the subjective test, but particularly as it was not argued, I need not decide the point. The end result would be the same. (I note that statute now mandates a subjective test, with evidence from the relevant person as to what they would have done, made inadmissible: Civil Liability Act 2001, s13(3).)
203 In this case there is no direct evidence, and in the absence of such evidence it is a question of whether I am prepared to draw the inference; RTA v Dederer [2007] HCA 42; (2007) 234 CLR 330 per Gummow J at [40], State of Victoria v Subramanian [2008] VSC 9; (2008) 19 VR 335 at [57], and Fox v Leighton Contractors Pty Ltd (above) per Basten JA at [58]. Even where there is direct evidence, it is still a matter for the determination of the Court, having regard to the hypothetical nature of the exercise, the dangers of retrospective reasoning, and the use of hindsight: Rosenberg v Percival [2001] HCA 18; (2001) 205 CLR 434 per Kirby J at [158], per Callinan J at [214]; Hoyts Pty Ltd v Burns [2003] HCA 61; (2003) 201 ALR 470 at [64] Ellis v Wallsend District Hospitals (1989) 17 NSWLR 553 at 560, 581.
204 The plaintiff said that he had no difficulties with the "Ten Commandments" document and that he was "fine" with it. Precisely what all that meant was not explained. Although oddly enough, the DECA assessment did not contain any adverse comment as to the speed at which the plaintiff negotiated corners, generally it shows a competent driver alert to his responsibilities. From the whole of the evidence, I infer that the plaintiff was fond of his job and took his responsibilities seriously. On several occasions he brought to the attention of management, problems he had with the truck's handling and said what he thought to be the reasons. He obviously felt strongly enough about this to speak directly to Mr Vanderwal on one occasion, notwithstanding a company directive not to raise operational problems with company directors. Although the evidence is meagre as to this point, I am prepared to infer that on the balance of probabilities, had the plaintiff been trained, and warned against excessive speed having regard to actual or potential handling problems with the truck, he would have complied and driven more cautiously. Consequently, speed would not have been a material contributing factor in the accident.
205 Of the nine particulars of contributory negligence alleged, those ultimately pursued related to the failure of the plaintiff to have his load adjusted before he set off on the journey, and his excessive speed through the corner. It is said that he failed to properly check his load and require that it be correct before he left on the journey, and that he failed to drive within the "limitations of his vehicle". The use of those words is linked to the plaintiff's own evidence that he knew to drive within such limitations provided by the feedback from the vehicle.
206 In my view, the practice of driving at the speeds at which the plaintiff customarily did in excess of the speed advisory sign, was one fraught with danger. The evidence makes it clear, as I have previously mentioned, that the margins of safety, particularly with loaded log trucks, are slim. In this respect I refer to Mr Brazendale's evidence who, when he took over the plaintiff's truck after the accident, drove through the corners at some 10km/h or so less than the plaintiff regularly did. He was not asked about why he did this, nor did he offer any reason. There appears to have been no reason why the plaintiff could not have adopted this practice. On his own admission he was under no time pressures.
207 In Astley v Austrust Ltd (1999) 197 CLR 1 at [30] Gleeson, McHugh, Gummow and Hayne JJ said (omitting references):
"A finding of contributory negligence turns on a factual investigation of whether the plaintiff contributed to his or her own loss by failing to take reasonable care of his or her person or property. What is reasonable care depends on the circumstances of the case. In many cases, it may be proper for a plaintiff to rely on the defendant to perform its duty. But there is no absolute rule. The duties and responsibilities of the defendant are a variable factor in determining whether contributory negligence exists and, if so, to what degree. In some cases, the nature of the duty owed may exculpate the plaintiff from a claim of contributory negligence; in other cases the nature of that duty may reduce the plaintiff's share of responsibility for the damage suffered; and in yet other cases the nature of the duty may not prevent a finding that the plaintiff failed to take reasonable care for the safety of his or her person or property. Contributory negligence focuses on the conduct of the plaintiff. The duty owed by the defendant, although relevant, is one only of the many factors that must be weighed in determining whether the plaintiff has so conducted itself that it failed to take reasonable care for the safety of its person or property."
208 In this case, the plaintiff was aware that there was something particularly unusual about the load. Mr Gill had stopped loading the front bunk when the gauge read 50kpa, saying that it was too much. More logs were put on after that. The truck in question had a history of handling problems of various descriptions. I have found that some of these were alleviated to some extent, but were not totally resolved. On the night of the accident, the truck was behaving in a foreign manner. I need not detail that evidence again. This handling behaviour was a matter which ought to have put the plaintiff on notice that care may be required, even though the change was seemingly for the better. On his own evidence, the plaintiff noticed that the gap between the drive wheels and the mudguard was excessive to what was normal.
209 All of this notwithstanding, the plaintiff did nothing to lessen, or even out the load, as it was within his power to do. He did not moderate the way in which he usually drove the truck through the bends. It is true that he had already negotiated the bends once that night with the same handling challenges apparent, but it was after that first load that he noticed the change in mudguard height, and of course, there is the question of the second load itself. This was not an instance of the plaintiff merely "performing his duties according to his habitual and long-standing practice"; Davies v Adelaide Chemical & Fertilizer Co Ltd [1946] HCA 47; (1946) 74 CLR 541 at 551 - 552. Nor do I think that driving into and around the bend at his usual speed in the prevailing circumstances, was something done out of a "misguided, but understandable, endeavour on the part of the worker to fulfil his ... employment duties in a reasonable way"; Liftronic Pty Ltd v Unver (2001) 75 ALJR 867 per Kirby J at [89].
210 In my view the plaintiff failed to take reasonable care for his own safety. The exercise is to assess the degree of departure from the standard of care of the reasonable person and of the relative importance of the acts of the parties in causing the damage. It is the whole conduct of each party in relation to the circumstances of the accident which must be subjected to comparative examination; Podrebersek v Australian Irons and Steel Pty Ltd [1985] HCA 34; (1985) 59 ALJR 492 at 494.
211 Of significance in this exercise is that the defendant provided the plaintiff with a truck fitted with a load measuring system which effectively involved "guesswork". At the same time, it provided erroneous advice as to the pressure which would represent the appropriate load on the drive axles, and instructed him to attempt to achieve the maximum legal load with tolerances. Of particular significance is that I have found that the plaintiff's speed was at least, contributed to by the defendant's negligence in failing to instruct or warn him against that practice in particular circumstances. Those circumstances existed in relation to the load on the night. In my view, it is just as between the parties, that the plaintiff bear responsibility for his injuries to the extent of 20 per cent.
212 There will be judgment for the plaintiff against the defendant for the agreed amount of damages, subject to a reduction of 20 per cent for the plaintiff's contributory negligence.
# Beswick
Tamarack Pty Ltd \[2009\] TASSC 109
(2001) 52 NSWLR 705
(2003) 205 ALR 145
(2007) 245 ALR 15
(2007) 159 FCR 397
(1984) 155 CLR 306
(1979) 23 ALR 513
(1999) 171 CLR 506
(1992) 176 CLR 408
(1988) 192 CLR 431
(1997) 42 NSWLR 307
(1998) 195 CLR 232
(2001) 205 CLR 434
(2007) 234 CLR 330
(2008) 19 VR 335
(2003) 201 ALR 470
(1989) 17 NSWLR 553
(1999) 197 CLR 1
(1946) 74 CLR 541
(2001) 75 ALJR 867
(1985) 59 ALJR 492