This paper presents a study which aimed to develop a quantitative model for evaluating transportation demand management (TDM) plans, as part of the requirements for Travel Reduction Ordinances (TROs) that help to address increasing congestion in American cities. It was necessary to select a region with a history of implementing TROs, and with sufficient affected work sites to permit statistical analysis. The only region with these characteristics is the South Coast Air Quality Management District (SCAQMD) in California. SCQAMD implemented Regulation XV, its regional TRO, in 1988, which requires over 6000 companies in or near Los Angeles to file an annual plan, reporting their transport status and transport control status, with a view to increasing car occupancy in journeys to and from work. 508 companies were surveyed. Discriminant analysis was found to be an acceptable methodology, which can be used to evaluate TDM plans more accurately. The resulting discriminant function can be used to predict the probability of a work site meeting its target average vehicle ridership (AVR). The analysis also identified which vehicles determine the AVR status of work site; this allows TDM planners to create specific programmes adapted to work sites.
Abstract