Improving regional transportation system performance through increased suburban intermodalism: A user cost modeling approach

Jeffrey Michael Casello, University of Pennsylvania


This research presents a Systems Approach—a combination of economic theory, spatial analysis and transportation modeling—to analyze the effects of increased intermodalism on transportation system performance. Using utility theory, a cost model is developed to explore conceptually the relationship between auto pricing, transit quality of service, and mode choice on a simple network. The model results suggest that increasing the disutility of automobile travel while providing high-quality transit can reduce total system and average user costs at a sustainable user equilibrium. The conceptual approach is extended to a sub-regional, multimodal route choice model of the Philadelphia, Pennsylvania network, concentrating on the region's most congested highway links. The model's trip table is generated by choosing trips ends for which transit competes effectively with private automobiles. The transportation literature suggests this occurs in areas with high-density land uses. Urban economists and spatial analysts call these locations “activity centers” and define them based on employment data. This definition is extended to include classifications of centers and, more importantly, the trip-generating characteristics of a center's employment. This new definition is applied to the Philadelphia metropolitan region using GIS. From the centers identified, eight are chosen for the sub-model due to their proximity to highly congested links. The sub-regional route choice model quantifies the impacts of changes in auto and transit generalized costs on transit share and regional system performance. Pertinent measures of effectiveness include transit modal split, total system delay (network congestion) and a transit “competitiveness” measure defined for individual and aggregated trip ends. The model is solved using an origin-based algorithm that converges much more rapidly and achieves much higher accuracy than earlier algorithms. Three auto disincentives measures are tested individually with limited improvement in system performance. Similarly, three transit incentives are evaluated; only modest gains in system performance are observed. Finally, combinations of auto disincentives and transit incentives are implemented. The combined measures markedly improve system performance and reduce user costs compared to the measures testes independently, thereby validating the conceptual findings on a sub-regional level. The research concludes by discussing model limitations and possible extensions of the work.

Subject Area

Civil engineering|Systems design|Urban planning|Area planning & development

Recommended Citation

Casello, Jeffrey Michael, "Improving regional transportation system performance through increased suburban intermodalism: A user cost modeling approach" (2003). Dissertations available from ProQuest. AAI3109161.