University of California Transportation Center

Rail transit has become a political lightning rod. Critics view rail proposals as among the most flagrant forms of pork barrel politics today. Advocates counter-argue that expanding the nation's rail transit offerings will yield many under-appreciated environmental and societal benefits, including reduced carbon emissions and dependency on foreign oil supplies.

If fixed-guideway transit is to yield appreciable dividends, there must be a close correspondence between transit investments and urban development patterns. All to often, rail transit investments in the U.S. have been followed by growth that is oriented to highway rather than transit corridors. Put simply, "mass transit" needs "mass" - i.e. density. For investments to pay off, there must be an unwavering local commitment to substantially raise population and employment densities along transit corridors. While dense areas average higher transit capital costs as well as higher ridership, our analysis suggests that many transit stations in the U.S. have nearby job or population densities that are too low to support cost-effective transit service. The thresholds in this study can provide cities and towns with targets for zoning around existing and proposed transit stations based on projected costs.