Assessing Bike-Transit Accessibility

Bicycles are a potential first-last mile mode that can augment the service area of public transit, yet it is difficult to fully account for bike-to-transit trips in planning and travel demand modeling processes. This paper presents a methodology for assessing bicycle first-last mile trips from one area to many possible areas using three visualizations on accessibility, travel times, and transit mode(s) utilized. Two configurations of bicycle first-last mile travel are considered: bringing the bicycle aboard transit to have the bicycle for biking at both ends of the trip (bike-transit-bike) and leaving the bike at the first stop (bike-transit-walk). Three locations in and near Atlanta, GA, U.S., are selected for analysis, and the optimal routes to all possible destinations in the transit service area are calculated for walk-transit-walk, bike-transit-walk, and bike-transit-bike. The walking and biking portions of trips are modeled using Dijkstra's algorithm, and the transit portion is modeled using the round-based public transit optimized routing (RAPTOR) algorithm. Results indicate that bike-transit-bike and bike-transit-walk decrease travel and wait times for transit, and in many cases reduce the number of transfers required compared with walk-transit-walk. Transit services with higher travel speeds or frequencies, such as heavy rail, greatly increased the number of accessible destinations and reduced travel times. Thus, an origin's distance to rail service had a major impact on the number of accessible TAZs. Planners and engineers can use this research to examine how public transit service changes and new cycling infrastructure can affect the accessibility of bike-transit trips.