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CHAPTER 5 Travel Demand Considerations Reliable estimates of travel demand both for a station as a whole and for the station's individual passenger access modes are important, but elusive challenges. The goal is to produce reasonable and reliable estimates that can be used to evaluate access planning options and to provide input to facility design. Ridership demand can be estimated for three basic conditions, representing decreasing levels of existing knowledge: (1) existing stations, (2) new stations along an existing (or extended) rapid transit line, and (3) stations along an entirely new proposed line. This chapter reviews current ridership estimating practice. It presents guidelines for estimating station ridership and access modes, including a ridership estimation model that was specifically developed for this research using data from many cities and over 450 individual stations. The station access planning tool is available on the CD accompanying this report, and online at Appendix C provides further details about this tool, including instructions for its use. Appendix B and the literature review developed for this research study (TCRP Web-Only Document 44: Literature Review for Providing Access to Public Transportation Stations) provide additional detail on existing evaluation tools and demand modeling techniques. Review of Practice Travel demand models are a familiar tool for estimating transit ridership and have been used for decades to predict transit ridership for rapid transit services, especially large capital projects. Appendix B provides a detailed summary of the current state of travel demand modeling with respect to transit access. Nearly all MPOs have demand models available, and most of these models provide at least some level of ability to estimate transit use. Thus, most transit agencies have access to at least some travel demand model without the need to develop in-house expertise in building and calibrating demand models However, many existing demand models lack the sensitivity needed to adequately assess the impacts of specific transit station access alternatives. TRB Special Report 288: Metropolitan Travel Forecasting: Current Practice and Future Direction evaluated the ability of current travel demand models to meet a broad set of needs, including modeling transit demand. This report noted several issues with current travel demand models that impede their ability to accurately assess transit access modes. As detailed in Appendix B and TCRP Web-Only Document 44: Literature Review for Providing Access to Public Transportation Stations, this research effort conducted a detailed review of published 44

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Travel Demand Considerations 45 literature on transit access demand. This review suggests several specific factors that appear highly correlated with access decisions and will likely be important in any transit access model: Parking cost and supply; Quantity and quality of feeder transit service; Type and diversity of land uses; Residential and employment density; Quality and continuity of pedestrian facilities; Station area demographics; Safety; Auto ownership; and Travel time. Factors that are positively correlated with auto access include parking supply and auto ownership, while factors positively correlated with walking access include density and land use mix. No one model incorporates all of the factors listed above and some are used as proxies for other factors. For example, higher densities and a mix of uses tend to be correlated with higher quality pedestrian infrastructure. Several studies also emphasize the importance of concentrating residential development within a -mile radius of a rapid transit station. Residents who live within a 5-minute walk of transit stations are 2.7 times more likely to commute by rail (12). Most pedestrians are willing to walk up to mile to access stations. For each additional 0.3 mile of walking distance, the probability of walking drops 50 percent. Density, local retail, and absence of major arterials near the station are the most important factors influencing walk trips to BART, together with individual characteristics such as gender and availability of a car (13). WMATA (Washington, D.C.) finds that the likelihood of riding rail transit declines as the distances to both residential and non-residential developments near stations increase. A zone study indicated the access percentages shown in Exhibit 5-1. Exhibit 5-2 shows how the percent of riders using transit in Toronto, Edmonton, Washington, D.C., and San Francisco declines as distance from the rail station increases. With regard to bicycle access, the international literature review shows that it is possible for bicycles to comprise up to 40 percent of transit access trips. However, realizing such a high percentage is largely dependent on factors outside transit agency control, as system-wide quality of bicycle facilities, topography, weather, and bicycle culture all play large roles in people's willingness to bike. Even so, research indicates that provision of bicycle facilities at transit stations, in particular high-quality bike parking, does have a significant impact on bicycle access. Exhibit 5-1. Development distance related Metro rail ridership (2002). Percent Using Rail Distance Office (%) Residential (%) At Station 35 54 -mile 23 43 -mile 10 31 Source: Adapted from TCRP Report 95 (14, 15 )