it was realized during the second GLTS calibration of the 1971 data that junctions were important, especially in the central area, and that speed/flow curves on links were inadequate to deal with crossing traffic at junctions. Initially, from 1975, a rather simple formula was used to incorporate delays at junctions, but from 1978 the standard formula devised by Webster (1958) was used. Whilst this considerably increased computing time, it was realized that this was worthwhile.
the value of time for car and public transport users was changed to a common value when evaluating benefits, rather than using separate values to represent the average user of each existing mode as in the calibration and forecasting stages.
the car operating cost was changed to incorporate link time as well as link distance.
the deterrence functions were estimated from a computer-based method, rather than the relevant parameters being estimated manually from the output and then being fed back into the computer.
KeywordsTransportation Income Petrol Tral Wharf
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