6. The learned trial judge, Ash J., accepted the evidence of experienced and expert planners that, when a plan for a significant urban area is proposed, it is necessary that there be a satisfactory relationship between planning proposals and the transport system that is or will be available. Feasibility in the planning sense therefore encompasses a correspondence between the transport demands to be expected when a plan of development is implemented and the capacity of the transport system which serves or will serve the relevant area. In preparing the Study documents, however, no adequate research into or analysis of the capacity of the transport system was undertaken or commissioned by the Authority. There was evidence, given by a transport engineer, that the rail and road traffic generated by a workforce of even 35,000 would have caused unacceptable congestion at the Town Hall underground station and on the roadways leading to Woolloomooloo. That opinion was a matter of controversy at the trial and there is no finding that the transport system would not have been capable of meeting the demands of a workforce of 35,000. However, his Honour found that there was a significant error in estimating what the size of the workforce would be if the Study were implemented. The calculations on which the estimate of 35,000 was based were not given in evidence. Obviously the size of the workforce depended on a number of factors: on the extent of site amalgamation, for that determined the maximum floor space ratio which might be permitted; on the floor space ratio actually approved for particular sites; on the proportion of space in the new development allocated to particular uses, for office use attracts the highest number of workers per unit of floor space; on the average area that would be occupied by an office worker; and on a decision by the Commonwealth whether it would develop a large site which it owned as an office block. Ash J. found that the Authority's "'envisaged' workforce figure was very wrong and resulted from very inadequate work including the items of research, investigation and calculation in the preparation of the Study". Whether or not the transport capacity was adequate for a workforce of 35,000, it was clearly insufficient to support a redevelopment which would, on his Honour's finding, "involve a workforce well in excess of 35,000". That finding must be taken to mean that if the Council exercised its powers as the Study documents proposed, the resulting redevelopment would have generated the larger workforce. There is a logical difficulty in accepting that finding, because the Study documents did not prescribe the manner in which the Council would exercise its powers in particular cases and, had the Council continued to regard the plan as its guide to the exercise of its powers, it might nevertheless have exercised its powers so as to restrict development in order that the workforce should not exceed 35,000. However, let it be assumed that the plan was not feasible in the planning sense, because redevelopment along the lines proposed would have generated a workforce - whether 35,000 or more - in excess of the capacity of the transport system to cope. For reasons to be stated, that finding does not suffice to establish the plaintiffs' claims.