This paper describes the simulation process developed by the Delaware Valley Regional Planning Commission to forecast travel demand for the bi-state Philadelphia metropolitan area. The modeling concept consists of a four-step process. Trip generation (step 1) uses a disaggregate trip rate; and it requires extensive knowledge of the magnitude and location of regional activities such as land use, employment, and the demographic characteristics of the resident population. Trip distribution (step 2) uses a typical gravity formulation stratified by trip purpose. Mode choice (step 3) estimates the proportion of the trips between two zones that will use the transit system and the proportion that will use the highway system. The final step of the process is the assignment of the various types of trips to the transportation system networks. Also described in this paper is a modified simulation technique (MST)--which is applicable to the study of changes in mode choice resulting from changes in service level, skip-stop or express service, station spacing, and shifts in route alignment. The underlying assumption is not that the primary transit submode route does change, but that the specific links of the path might change. The primary impact of these service changes will be in the level of transit mode choice for a given trip interchange. The MST does provide a useful and cost effective means around the expense of the standard simulation process; although, its applicability is limited to those studies where the underlying assumption of "no significant change in primary transit submode route" is considered a reasonable approximation.

Media Info

  • Media Type: Print
  • Features: Figures; References;
  • Pagination: pp 209-211
  • Monograph Title: Transportation forecasting and travel behavior
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00196017
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Sep 15 1981 12:00AM