Urban planning credo states that, through design and policy interventions that improve access to public transportation, Transit-Oriented Development (TOD) reduces car dependency and encourages individuals to walk, bike, bus, or take the train to their destination. Well, maybe. A University of California, Berkley study suggest that, for rail, the T in TOD may not be necessary to reduce car travel in neighborhoods that are dense and walkable, with scarce parking.
In a study of rail transit’s impact on travel patterns, Daniel Chatman, associate professor in the Department of City & Regional Planning at UC Berkeley, challenged the assumption that easy access to rail leads to less reliance on cars (and subsequently lower rates of car ownership). Were there other factors at play, like narrower streets, good parking, wider sidewalks, and nearby destinations?
Chatman received over 1,100 responses to a survey he sent to households living within a two-mile radius of ten New Jersey train stations, within commuting distance to Manhattan. Chatman asked residents about what type of house they lived in, on- and off-street parking availability, travel for work and leisure, residential location preferences, and household demographics. 30 percent of respondents lived in housing that was less than seven years old. Half lived within walking distance (0.4 miles) to rail, in TOD-designated and non-designated developments.
Controlling for housing type, bus access, amount of parking, and population density, among other markers, the availability of on- and off-street parking, not rail access, was the key determinate in auto ownership and car dependence. The study asserts that “households with fewer than one off-street parking space per adult had 0.16 fewer vehicles per adult. Households with both low on- and off-street parking availability had 0.29 fewer vehicles per adult.” Living in a new house near a train station, moreover, was correlated with a 27 percent lower rate of car ownership compared to residents further afield.
Bus access was also key in determining car use. The number of bus stops within one mile of a residence is a good indicator of public transit accessibility, and there are usually more bus stops in denser areas. The study found that “doubling the number of bus stops within a mile radius around the average home was associated with 0.08 fewer vehicles per adult.” Compared to areas with poor bus access and plentiful parking, car ownership was reduced by 44 percent when strong bus access converged with poor parking availability.
To reduce car ownership and use, municipalities don’t necessarily have to invest in rail. Reducing the availability of parking, providing better bus service, developing smaller houses (and more rentals), and creating employment centers in walkable, densely populated downtowns may accomplish the same objective, at considerably less expense.