Planning skip-stop services with schedule coordination

This paper develops a continuum approximation model for simultaneously designing and coordinating an AB-type skip-stop service, which had been successfully operated in many places (e.g., Chicago, Philadelphia, and Portland in US and Santiago in Chile). The model accounts for spatially heterogeneous demand patterns in transit corridors. Thanks to the parsimonious property, a solution algorithm is developed using calculus of variations and direct search method. In numerical experiments, a variety of scenarios were examined with respect to 14 operational schemes (i.e., the all-stop scheme, the uncoordinated skip-stop scheme, and the coordinated ones of 12 coordination plans), 2 transit modes (i.e., regular bus and rail), and 3 demand patterns (i.e., uniform, low-varied and high-varied demand). The results indicate: (i) the additional benefit of schedule coordination is 2–3% for uncoordinated skip-stop services, which eventually may add up to 6% cost saving as against the traditional all-stop service; (ii) among all coordination plans, the simplest common-headway plan often works best in all tested scenarios; and (iii) for rail system, the operation of the coordinated skip-stop service is very costly due to the requirement of building an extra track, and positive benefit only emerges in the very busy corridors. Lastly, a case study in Chengdu (China) using real surveyed demand data illustrates the application of our model.