The effect of Park-n-Rides on greenhouse gas emissions.

摘要

Over the past decade, rising greenhouse gas emissions (GHG emissions) have put public transit in the forefront of sustainable transportation. To improve transit accessibility and attract riders, Park-n-Ride (PnR) facilities have been built on the periphery of cities. By providing convenient parking facilities, agencies encourage drivers to shift modes in their single occupancy vehicle (SOV) and complete their journey by transit.;While PnRs are intended to facilitate more transit riders, the facilities may also carry paradoxical consequences. Do PnRs actually reduce the distance traveled by SOVs? Does a multi-modal trip offset emissions from a theoretical SOV drive-only trip? Critics have challenged the environmental efficiency of PnRs, claiming the magnitude of the modal shift may not necessarily be reflected in GHG emissions. Drivers may still make long trips by car to reach the PnR.;This study evaluates the magnitude of GHG emissions saved from transit ridership, based on SOV PnR users in the Denver metro area. By comparing the multi-modal trip against a theoretical SOV drive-only trip, the effects from GHG emissions are weighed. Theoretically, the further a person drives to reach a PnR, the less of an impact transit has on reducing GHG emissions.;Results showed that PnRs located at inner-corridor stations are less effective at reducing GHG emissions than end of line stations. PnRs near downtown provide an incentive for longer SOV drives. Consequently, drivers who make long transit access trips can outweigh the benefits of transit usage due to increased vehicle emissions.