Exploring alternative service schemes for busy transit corridors

Abstract

Transit systems in which buses or trains always visit each and every stop along corridors are compared against those that feature two alternative vehicle-dispatching schemes. The alternatives entail so-called skip-stop and express/local services. Continuous models found in the literature are expanded so that the alternatives could be compared under a wider array of options. Comparisons are separately drawn for systems that feature buses, BRT and metro-rail trains, both for cities that are wealthy and for those that are not. Idealizations in regard to travel demand and route symmetry are assumed in pursuit of insights useful for high-level planning. Two rounds of parametric comparisons are conducted. In the first round, optimally-designed all-stop systems are presumably converted to furnish instead the alternative strategies without altering the original stop locations. In the second round, alternative schemes are designed in fully-optimized fashion from scratch. In both rounds, alternative dispatching schemes often bring lower generalized costs than do their optimally-designed all-stop counterparts. Estimated savings can reach 10% even in the first round where the alternative schemes are hampered by sub-optimal stop locations. If designed from scratch, the savings can reach 30%. Skip-stop service is found most often to be the lowest-cost option of the three.