Shared-Vehicle Mobility-on-Demand Systems: A Fleet Operator's Guide to Rebalancing Empty Vehicles

The authors consider the operation of automated mobility-on-demand systems, whereby users share access to a fleet of self-driving vehicles. In these systems, rebalancing, the process by which the supply of empty vehicles is periodically realigned with the demand for transport, is carried out by a fleet operator. Where much of the rebalancing literature skews to the theoretical or simulation-based, the authors consider shared mobility systems from the perspective of the fleet operator. The authors test, via simulations, how key performance metrics vary as a function of fleet size and rebalancing policy using rental data from car2go, a free-floating carsharing service operating in markets across Europe and North America. Results reveal that rebalancing can dramatically reduce the number of customer walk aways, even for relatively small fleet sizes. A framework is provided to assess what fleet size is a appropriate for a city factoring in the cost of vehicles, customer walk aways, and the added expense of moving empty vehicles.