Assessment of the transfer penalty to transit trips in Downtown Boston : a GIS-based disaggregate modeling approach

Abstract

This research aims to examine the impacts of transfers since transfer activities have significant implications not only for the daily operation of a transit system, but also the integration and coordination between transit lines. Transfers affect transit system performance in at least two respects. On the one hand, the use of transfers in the design of transit services provides more options for the transit operator in terms of area coverage, resource allocation, and flexibility. These factors result in better overall service. On the other hand, transit users do not seek to make transfers on their trips unless there is no alternative or the transfer offers a compelling performance advantage for a given trip. Exploring this trade off associated with transfers helps in understanding passenger dissatisfaction with the transfer, or the transfer penalty. A trade off between making a transfer and extra walking time is explored using a binary logit choice model to review the existence of the transfer penalty, the components inside the penalty, the effects of the urban environment outside the transit system, and the variation of the penalty across trip and personal characteristics. The MBTA subway system in Downtown Boston is used for the analysis, and GIS techniques are used extensively for data processing and results display. The study shows that there is indeed a perceived transfer penalty among MBTA subway riders. Transfer walking time, transfer waiting time, the change of level, and the existence of concession capture the majority of the penalty. The remaining part is explained by the general condition of the subway transfer station, and the in-vehicle travel time spent on making a transfer. The study also shows there is a variation of the transfer penalty across different transfer stations. The urban environment in Downtown Boston as explained by measures, such as sidewalk width, land use, open space, and topology, also has a significant impact on the transfer penalty. In particular pedestrian friendly Downtown area encourage riders to leave the subway system early and walk further. The penalty is found to be largely independent on the trip and demographic characteristics though this finding may be affected by the population being limited to those who already choose the subway system to reach their final destinations in Downtown Boston.