Dynamic Interaction between Shared Autonomous Vehicles and Public Transit A Competitive Perspective

Document pages: 27 pages

Abstract: The emerging autonomous vehicles (AV) can either supplement the publictransportation (PT) system or be a competitor with it. This paper focuses onthis competition in a hypothetical scenario-- "if both AV and PT operators areprofit-oriented, " and uses an ABM to quantitatively evaluate the systemperformance in this competition from the perspectives of four stakeholders--AVoperator, PT operator, passengers, and public authority. In our model, AVoperator updates its supply by changing fleet sizes while PT by adjustingheadways, and both use heuristic approaches to update supply in order toincrease profits. We implement the model in the first-mile scenario inTampines. In four regulation scenarios--two by two combinations regardingwhether AV and PT are allowed to change supplies--we find that since AV canrelease the bus operator from low-demand routes, the competition can lead tohigher profits of both, and higher system efficiency, simultaneously, ratherthan a one-sided loss-gain result. For PT, after supply updates, spatially theservices are concentrated to short feeder routes directly to the subwaystation, and temporally concentrated to peak hours. For passengers, thecompetition reduces their travel time but increases their travel costs.Nonetheless, the generalized travel cost is still reduced when counting thevalue of time. For system efficiency and sustainability, bus supply adjustmentcan increase the bus average load and reduce total PCE, while the AV supplyadjustment shows the opposite effect. For policy implications, the papersuggests that PT should be allowed to optimize its supply strategies underspecific operation goal constraints, and AV operation should be regulated torelieve its externality on the system, including limiting the number oflicenses, operation time, and service areas, which makes AV operate like acomplementary mode to PT.