Modelling practice in Australia ranges from innovative, through competent to thoroughly muddled insofar as the logic is concerned, even though the final traffic forecasting results might be acceptable for practical purposes. The main area where practice has often been thoroughly muddled is in the construction and use of trip tables but matrix estimation techniques have been used to restore these to lead to acceptable traffic forecasts even though the logic of their construction is aborted. The key to understanding why these examples are inappropriate is to recognise that trip generation, distribution and mode split are all functions of interzonal trip costs and therefore each of these models needs to be iterated with the congested outputs of the assignment models. This goes some way to ensure that network congestion is not overstated and that traffic on relatively uncongested toll-roads or freeways is more accurately represented. Further, all possible future road and public transport facilities should be coded in future networks to ensure that excessive congestion is treated. (Author/publisher) For the covering entry of this conference, please see ITRD abstract no. E211825.
Samenvatting