The Study On Characters Of Bus Route System Under Four Traffic Signal Control Strategies

With the economics rapidly developing and the urbanization level improving, the travel requirement of residents and motor vehicle population keep increasing. The traffic congestion has been one of bottlenecks restricting cities’developement. It’s one of effective methods to reduce traffic congestion by adjusting the ratio of residents’ travelling tools and encouraging more people to take bus. Nowadays, constructing dynamical models to explore the disciplines of the bus route system has attracted the interest of a community of scholars. Generally, these models consist of some basic elements such as buses, passengers, bus stops and so on.The bus route system controlled by traffic signal is modeled with the cellular automaton. The transition characters of the system controlled synchronized signal, random signal and green wave are studied in this paper. The main contents of the paper are as follows:1. The bus route systems controlled by synchronized traffic signal with period and open boundary are modeled, respectively. The simulation results show that the relationship between the average velocity and signal period is an oscillating curve in free-flow state. In addition, an analytical equation for the curve is proposed.2. Based on the relationship between flow and density for traffic flow, the critical passenger arrival rate against the bus number is derived, which is also the equation for the boundary line of the transportation capability. Each region in the phase diagram also oscillates synchronously when the boundary line changes.3. Two new states called "lag and catch" and "variant lag and catch" are discovered in the system. An accurate equation to judge the emergence condition of "lag and catch" is proposed.4. The bus route systems controlled by random traffic signal with period and open boundary are modeled, respectively. An analytical equation for the relationship between Vave and T is proposed with probability theory, which is an unbroken and increasing curve. "lag and catch" and "variant lag and catch" can’t exist stably under random traffic signal.5. The bus route system controlled by green wave traffic signal with open boundary is modeled. When the system is in serious congestion, the average velocity controlled by green wave is slower than the other signals. For other cases, green wave is better. An analytical equation for the relationship between vave. and T under insufficient transportation capability is proposed.6. Based on characters of synchronized traffic signal, a new traffic signal, i.e. multi-step signal is proposed. Finally, this paper compares the result of this strategy with that of synchronized signal, random signal and green wave. It can be seen that adjusting traffic signal control strategy to adapt the state of bus route in time could improve the efficiency of buses and the satisfaction of passengers.