When less is more: Exploring trade-offs in transit route concentration

Route concentration involves withdrawal of selected bus routes to redeploy buses on major corridors to concentrate service frequency in those corridors at no net additional cost. Much research supports high frequency as a means to grow ridership and several practitioners have recommended route concentration. However research demonstrating the value of route concentration is limited. In particular gaps in knowledge about the longer walk access distances caused by route concentration need to be better understood relative to the benefits of higher frequency. This research paper explores the net impacts of route concentration on ridership using a theroetical network and some simple but robust representations of the impacts of route concentration on walk access, frequency and wait time including ridership impact. Results demonstrate that the route concentration options tested acted to increase ridership by up to 10% whilst operations costs were the same. They provide strong support for the concept of route concentration as a basis for route network redesign to improve service effectiveness. However the results also suggested that there is a finite limit to which route concentration might be deployed. In the options tested a 1.2km route density achieved the highest ridership growth compared to a base case of 300m route density. Though lower density options had lower ridership growth suggesting long walk access distances can act to limit ridership benefits if route densities become too low. Sensitivity tests suggests a 1.2km route density was consistently the best suggesting a robust result. Implications for practice and future research are discussed