The BTCE (Bureau of Transport and Communications Economics) has developed a light vehicle traffic forecast methodology for use in assessing the adequacy of current and future infrastructure needs for Australia's major highways. A gravity model of population and real generalised travel cost was used to forecast aggregate inter-regional passenger travel. Passenger traffic mode share on major inter-city routes was estimated using a suite of logistic substitution models. Forecast mode shares were then applied to the aggregate passenger travel forecasts to derive light vehicle traffic forecasts. For this work the BTCE developed an extensive data set of passenger transport, covering the period 1970 to the present, using tourism survey data. Inter-regional light vehicle traffic was assigned to highways using the traffic assignment procedures in TransCAD. Assigned inter-regional highway traffic was subtracted from total light vehicle traffic count data to derive local traffic on each highway link. Forecasts were derived by type of vehicle, for each link in the highway system. Key features of the BTCE's method include the use of separate models of inter-regional passenger, local passenger and commercial vehicle traffic to forecast highway traffic levels, and the development of logistic substitution models for mode share. The logistic substitution models predict the mode share of air will continue to increase on longer routes, while the mode share for car will continue to increase on shorter routes. The BTCE has tested its methodology using Western Australian traffic count data, and found the forecast methods provide a good approximation to future traffic growth. (A)
Abstract