Comparing skip-stop and all-stop transit network designs

Skip-stop service is a public transportation scheme designed to improve operational speed and travel efficiency by skipping certain stops along a route. This paper focuses on the optimal design of a specific type of skip-stop service, known as AB-type service. While previous research primarily addressed corridor-level designs for this service, we present a continuous model to optimize an AB-type skip-stop service network in a square city layout. Our objective is to minimize the combined costs of the agency and patrons’ travel time by making optimal decisions about network design—including line and stop spacings—and the operational plan, consisting of the number of skip-stop routes and service headways. We conduct extensive numerical case studies to compare the performance of the skip-stop service with two variants of all-stop services: one incorporating non-transfer stops and one without. We examine two prevalent transit modes: rail and bus. The results indicate that the optimal skip-stop network outperforms all-stop networks in most scenarios for rail systems. In contrast, for bus systems, the all-stop service without non-transfer stops performs best. Interestingly, skip-stop service results in a lower commercial speed compared to all-stop services, and it also significantly reduces agency costs for rail systems. Moreover, we observe that the advantages of skip-stop service at the network level decrease as travel demand increases. These findings are contrary to those from corridor-level studies, highlighting the importance of understanding network-level dynamics when planning skip-stop services in a broader range.