The purpose of this investigation is to measure the impact of the public transit service level on the destination choices of trip makers. It is often hypothesized that trip makers will have a tendency to make more trips to areas with a relatively high level of public transit, particularly if the service is superior to that provided by the auto, and to make fewer trips to areas with poorer transit accessibility. This propensity is measured by comparing the error in travel volumes predicted by a standard Bureau of Public Roads highway time gravity model with the relative transit and highway service levels, as measured by the disutility difference measure used in most utilitarian modal split models. Doubly constrained gravity models were calibrated on the basis of highway travel times for three trip purposes: home-based work, home-based nonwork, and non-home. The results of the models were obtained for the Delaware Valley Region, which has an extensive public transit system--some 2900 route kilometers (1800 route miles) of high-type rail facilities. Examination of the results yielded the following conclusions: a highway-based gravity trip distribution model has a measurable bias in the Delaware Valley Region with respect to the relative public transit and highway service levels; this bias is well defined, rational, and statistically significant for home-based work, home-based non-work, and non-home-based trips; the bias varies only marginally by trip purpose, for only the non-home-based trips are significantly different from home-based work trips and total trips; the highway time-based gravity model has a significant tendency to underestimate person-trip interchanges even when the transit and highway service levels are equal; and the correction of the bias results in significant changes in the synthetic person-trip tables. Although these conclusions are drawn from a specific region, they can probably be generalized to other regions that now have or are considering some form of high-speed public transit service; because the total amount of transit service may not be as significant as the relative quality of transit service in individual corridors.

Media Info

  • Media Type: Print
  • Features: Figures; References;
  • Pagination: pp 200-202
  • Monograph Title: Transportation forecasting and travel behavior
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00196014
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Sep 15 1981 12:00AM