For the average American, the overwhelmingly popular first choice in trip mode is to get into the private car at point A and drive it directly to point B. In the San Francisco Bay Area, for example, 82 percent of all work trips and 76 percent of all non-work trips are solo car trips. The total share of transit trips is 10 percent and steadily declining, in spite of massive operating subsidies for these modes. Short of a drastic change in the cost of car travel (e.g., a long-term doubling of gasoline prices), current transit modes cannot hope to compete with the private automobile for passengers.

Electric station cars have the potential of filling an important market niche -- namely, providing on-call, door-to-door access to and from rail transit stations as well as midday automobility for those who patronize transit. They would make getting from home to work via rail transit virtually seamless. Their greatest promise is in the suburbs. In the San Francisco Bay Area, there are thousands of jobs beyond walking distance of suburban BART stations. Given the choice of driving from home to work or taking BART and transferring to a bus to reach jobs, most suburban workers choose the former. The availability of free parking at the workplace and the generally poor quality of many suburban bus services reinforce this overwhelming preference for solo commuting.

To date, far more research has been conducted on the effects of the built environment on transit demand along mainline corridors than in the catchment zones surrounding transit stops. Pushkarev and Zupan (1977), for example, correlated transit ridership for the line-haul segment of trips as a function of residential densities, distance to downtown, and size of downtown; however, they ignored how access trips to transit stops were influenced by such factors. Seminal work by Meyer, Kain, and Wohl (1965) studied factors influencing bus and rail transit demand for three segments of trips -- residential collection-distribution, line-haul, and downtown circulator -- however, their work did not examine the direct effects of land-use variables. For example, in the case of access trips from home to rail stations, or what they call the residential collection-distribution segment, the number of "trip origins per city block" was used as the predictor of access demand. Standard trip generation rates were used to directly estimate access demand.