SUPPLY-SIDE ANALYSIS AND VERIFICATION OF RIDERSHIP FORECASTS FOR MASS-TRANSIT CAPITAL PROJECTS

The ridership carried by fixed-guideway transit projects in the United States has typically fallen short of that forecast during early planning stages. The forecasts appear to have been prepared without adequate consideration of service supply factors. This article outlines three principal parameters for supply-side analysis: 1) maximum service level (vehicles per hour); 2) maximum utilized capacity or vehicle occupancy (passengers per vehicle per hour); and 3) the share of weekday ridership carried during the busiest hour in the busier direction. Supply-side analysis suggests that demand-supply equilibrium as a determinant of transit ridership was not addressed during early planning for several recent fixed-guideway projects. The facilities in question, as built, are not capable of accommodating peak-period loadings of the size implied by the forecasts. The principal limiting factor is vehicle fleet size, although limitations on maximum train length and maximum service frequency are characteristic of light rail installations.