Models And Simulations Of Bus Route System Based On The Cellular Automaton

In the urban transport, the main reason for traffic jam is too many vehicles with insufficient few road resources. But the bus system is the transportation mode with few energy consumption and high efficiency. Comparing with the private car, the bus takes few road resources, has large capacity and brings little pollution; comparing with track traffic, the bus system needs few invests, and can adjust its line more flexible. Therefore the fully developed bus system is one of the effective measures to reduce traffic congestion. However, the bus stop is a traffic bottleneck. It will seriously affect the traffic flow, not only cut the bus system's operating efficiency, but also reduce the social vehicles'running rate if it is set incorrectly. Based on those facts, this dissertation studies the influence of the bus stop on the road traffic. Modeling and Simulations are carried out by using the cellular automaton model. The influence of the two kinds of bus stop-harbor shaped and non-harbor shaped-is analyzed in detail, and the influence of the passenger flow volume in the station on the traffic flow is also studied. The main contents of the paper are follows:1. A two-lane system with bus route with period boundary is studied by a cellular automata model. The evolution characteristics and the operational efficiency are analyzed by plotting the fundamental diagram, space-time diagram and so on. The two types of bus stops, i.e., non-harbor shaped and harbor shaped, are considered, and the merits of the two types of bus stop are compared. The simulation results show that: there are four density regions with different evolution dynamics of traffic flow; the bus route with Harbor-shaped stop has less effects to the traffic flow and the maximum flow is higher than the bus route with non-Harbor-shaped stop.2. Considering the fact that the send off a bus is based on the specified time interval, and the open boundary reflects this point well. So, in this section, a two-lane system with bus route under open boundary is studied by a cellular automata model. This model simulates the bus system much more realistic. Further it is verified that the bus route with Harbor-shaped stop is superior to the bus route with non-Harbor-shaped stop.3. Considering that the arrival rate of passenger in the station is not all the same, in the CBD the stations has large flow of passengers, so the factor of stations'flow is not balance. In the model, a certain bus stop is set as a big station. The influence of the big station on the whole bus route system is analyzed. The simulation results show that the flow is lower than that without big station, and serious traffic jam has arisen nearby the big station.