Computer simulation study on city car system

We assume that 15 stations are set at the key points in a certain city and suitable number of small cars are distributed to each station and that basic 0-D data of trip between any two of these stations are given. In our simulation, passengers who take on cars at their stations are generated by using random number. If there is no car in a car pool and no arrival car, passengers generated at the station are set to be waiting until available cars appear. The redistribution process which redistributes the cars intentionally from some stations to other stations to regulate the number of parking cars at each station is taken in account. We observe the system behavior and stability by paying attention to the average waiting time of passengers in the simulation. We find out appropriate number of cars and redistribution capacity to realize some satisfactory service level of the system and keep the system stable. It is found that redistribution prccess reduces the necessary number of cars to realize some service level as well as keeps the system stable, but excessive redistribution capacity is not necessarily effective on improving the system performance.