Two Flow-Based Approaches for the Static Relocation Problem in Carsharing Systems

TL;DR

This paper introduces two methods, a heuristic and an exact flow-based approach, to optimize the static relocation of cars in carsharing systems, ensuring balanced station inventories.

Contribution

It presents a novel combination of a fast heuristic and an exact flow-based method for solving the static relocation problem in carsharing systems.

Findings

The flow-based method provides optimal solutions for small instances.

The heuristic offers faster solutions suitable for larger instances.

Computational results demonstrate the effectiveness of both approaches.

Abstract

In a carsharing system, a fleet of cars is distributed at stations in an urban area, customers can take and return cars at any time and station. For operating such a system in a satisfactory way, the stations have to keep a good ratio between the numbers of free places and cars in each station. This leads to the problem of relocating cars between stations, which can be modeled within the framework of a metric task system. In this paper, we focus on the Static Relocation Problem, where the system has to be set into a certain state, outgoing from the current state. We present two approaches to solve this problem, a fast heuristic approach and an exact integer programming based method using flows in time-expanded networks, and provide some computational results.