Individuals living in 152 households throughout portland, oregonwere exposed to various economic incentives designed to promote busridership, and corresponding reductions in automobile driving. The frequency of bus riding and the number of miles driven were recordedduring a 3-week baseline, 4-week treatment, and 2-week follow-up period. Following baseline, households were randomly assigned to one of the following conditions: (a) no treatment control; (b) credit only, where credit slips allowed subjects to board the bus for free andbe billed the full fare later; (c) credit + inverted fare, where individuals were billed for half of the fare if they rode the bus frequently; (d) credit + differential fare, where individuals were billed for half of the fare if they rode the bus during off-peak hours; and (e) free tickets where subjects were not billed for bus rides. The groups did not differ in bus ridership during baseline or follow-up periods. In contrast, during treatment, subjects in the credit + inverted fare and the free-tickets groups displayed significant increases in ridership. However, at no point in the study were increases in bus ridership associated with decreases in miles driven. These outcomes indicated that whereas selective economic incentives can facilitate ridership, such changes were not large and they did not lead to sustained increases in bus ridership or reductions in automobile driving. (A)
Abstract