Flexible Returning/Parking Strategies for One-way Car-sharing Systems

In one-way car-sharing systems, there are not enough parking places for users to return cars in many cases. Two flexible returning/parking strategies are proposed to solve this problem: parking cars in temporary spaces and unoccupied spaces. In the former strategy, users are allowed to return cars to temporary parking spaces nearest to the car-returning stations. In the latter one, users are encouraged to park cars in available spots in the same zone as the car-returning stations. A mixed-integer nonlinear programming model is developed to maximize the profit of car-sharing companies. The big-M method is applied to convert the nonlinear constraints into linear constraints, and the commercial solver is used to solve the transformed model. A case study shows that parking in temporary spaces and unoccupied spaces can improve the profits of car-sharing companies. The maximal profit increasing rates are 25% and 37%, respectively. When the number of parking spaces is lower than demands, parking to temporary spaces performs well in improving the profits. Under the same circumstance, the more temporary parking spaces the company rent, the higher profits the company can obtain.