# Performance Analysis of a Forecasting Relocation Model for One-Way Carsharing
## 2 Literature Review  
### Carsharing  
Carsharing, or what is traditionally referred to as neighborhood carsharing, began in Europe and placed a network of vehicles in strategic parking areas (mostly in residential neighborhoods) located throughout dense cities [20]. Basically, members subscribed to a carsharing company and paid a fee each time they used a vehicle, which covered the cost of vehicle use, insurance, maintenance, and fuel. One of the formal carsharing demonstrations in the United States was Mobility Enterprise, operated as a Purdue University research program from 1983 to 1986. Studies have shown that operators are more likely to be economically successful when they provide a dense network and a variety of vehicles; serve a diverse mix of users; create joint marketing partnerships; design a simple, flexible rate system; and provide easy emergency access to taxis and long-term car rentals [21]. The implementation of carsharing services can reduce vehicle distance travelled and also strengthen public transportation services. [PERSON] et al. showed that the greatest reduction in overall vehicle distance travelled including carsharing and private cars resulted from introducing round-trip carsharing across all of London [4]. In North America, station based car sharing has resulted in reduced emissions, due to fewer cars on the roads, and a 27% reduction in average vehicle distance travelled per year [5]. [PERSON] and [PERSON] showed that carsharing strengthened public transportation services, as revealed by its members who tended to reside in medium to high density areas and used public transportation frequently [22]. [PERSON] et al. [1] showed that carsharing provided the best option in terms of flexibility for intermediate length trips, while for longer trips, rental cars were usually less expensive, and for short distances, taxis tended to be more cost effective. Another important factor in carsharing is determining the optimal locations of future stations so that more people can be attracted by the carsharing service. [PERSON] et al. [23] utilized an analytic hierarchy process (AHP) and a geographical information system (GIS) to determine the location of carsharing stations. The potential users, travel demand, travel purposes, and distance from existing stations were selected as decision criteria. The study suggests that if there were enough parking spaces near a candidate site and the cost was acceptable, then the candidate site from the proposed model could be selected. Various reservation mechanisms are used in carsharing, ranging from manual systems, where users call a reservation center; to automated systems that can be accessed via the phone or Internet [24]. Reservation based carsharing provides control over demand flow and allows better prediction of the system's future state. Current services allow customer flexibility such as instant access (i.e., no reservations). [PERSON] et al. [25] compared instant access and reservation based one-way system performances by discrete event simulation, and showed that reservation based systems were better in terms of the utilization ratio and customer satisfaction (acceptance ratio). Reservation systems also help the operator to maximize car operation by minimizing uncertain return cars from previous customers. The study also suggested that the operator needed to provide a high number of operational cars for instant access one-way, maximizing profit and customer satisfaction. [PERSON] et al. [26] proposed a simulation model to optimize car operation for round-trip services. They showed that the number of cars and customer reservations impact customer satisfaction (acceptance ratio) and the utilization ratio. Thus, deciding the correct number of cars based on the current number of reservations allows target acceptance and utilization ratios to be achieved. Implementation of one-way services can be complementary to round-trip services, increasing customer trip flexibility.