Car relocation for carsharing service: Comparison of CPLEX and greedy search

In this paper, we present two approaches to solve the relocation problem in one-way carsharing system. We start by formulating the problem as an Integer Linear Programming Model. Then using mobility data collected from an operational carsharing system, we built demands matrices that will be used as input data for our solver. We notice that the time needed to solve the ILP using an exact solver increases dramatically when we increase the number of employees involved in the relocation process and when the system gets bigger. To cope with this problem, we develop a greedy algorithm in order to solve the relocation problem in a faster time. Our algorithm takes one second to solve the relocation problem in worst cases; also, we evaluated the robustness of the two approaches with stochastic input data using different numbers of employees.