공유 자전거 시스템의 수요기반 재배치

As the environmental effect is becoming increasingly important in urban life, an eco-friendly bike sharing system has been considered as a good alternative transportation system. Most of the bike-sharing systems operate in a one-way mode, in which users can borrow a bike from any station and return it wherever they want. Hence, an imbalance exists between the supply and the demand of each station, and in such a situation, the operators must relocate bicycles using an inter-station vehicle (truck). In this study, we focused on dynamic repositioning, which relocates bikes several times a day. A mathematical model for an optimal dynamic repositioning operation plan is proposed, which can be executed once a day. This model considers pickup and delivery vehicle routing under time constraints and aims to minimize the number of unbalanced bikes while ensuring target fulfillment as close as possible. The relocating vehicle may visit several stations to pick up and deliver bikes needed within a time allowed for operation. The suggested model is evaluated through the standard cases with reasonable size and the real cases of Seoul city as well. Results indicate that the bike-sharing system can be operated efficiently to meet demand with practical implementation validity