Transit Ridership, Auto Gas Prices, and World Events

U.S. transit ridership research covers a wide field of traveler response factors but is surprisingly limited concerning the impact of auto gas prices. This situation is unfortunate, because gas prices have driven unprecedented growth in transit demand over the past 2 years. The research literature concerning cross-modal market effects of auto gas prices on transit demand is reviewed, including an outline of modeling work conducted in Australia. An analysis of U.S. national transit demand and auto gas trends is presented: the cross-elasticity of demand (e) is modeled in aggregate and separately for U.S. heavy rail, light rail, and commuter rail, and bus. Results indicate that, in aggregate, U.S. transit demand is at the low to medium end of sensitivity to auto gas prices for countries that have a low mode share. This finding is consistent with the lower cost of gas in the United States compared with other countries. The aggregate e has been measured as 0.12 and indicates that total U.S. transit demand will increase by 1.2% for every 10% increase in gas prices. U.S. light rail is particularly sensitive to gas prices, with e values of 0.27 to 0.38. Bus ridership is only slightly sensitive to gas prices (e = 0.04), and heavy rail is higher (0.17), consistent with most international evidence. A longitudinal model of trends has suggested some acceleration in transit mode sensitivity as world events have continuously affected prices; however, the model suggests that the effects since Hurricane Katrina (August 2005) have softened.