Optimising modular-autonomous-vehicle transit service employing coupling–decoupling operations plus skip-stop strategy

Modular autonomous vehicles (MAVs) have enormous potential to accommodate spatio-temporally imbalanced demand by coupling and decoupling flexibly in operation. The existing work in the literature on MAV service mode design is focused on the matching between supply and demand not at the bus-stop level but at the bus-route level. To fill the gap, this work proposes a novel MAV service mode that incorporates coupling–decoupling operations en route plus skip-stop strategy and simultaneously determines the number of MAVs and headways required for each trip, MAVs' coupling and decoupling scheme, and each MAV's skip-stop scheme. A mathematical programming formulation is devised to minimize the total cost of a transit service to the operator and to the passengers by using a trip-extended network approach while environmental impacts of energy consumption savings are considered with the operation of coupling multiple MAVs as a platoon. A case study of a real-world bus line in Dandong, China, shows that, compared with the prevailing service modes with no coupling–decoupling operation at intermediate stops or a skip-stop strategy, the mode designed in this work reduces the total cost of the transit system by 9.87%–32.09% and the passenger travel cost by 17.92%–38.54%.