A study for the traffic flow control considering the capacity of the road by cellular automaton method

Traffic problems have been studied for a long time to relieve traffic jams and increase transportation efficiency. In recent years, a cellular automaton method has been applied to simulation of traffic flow control. By using the cellular automaton method, a simulation of traffic flow inside the control area, which includes four crossings with traffic lights, has been carried out under the control of traffic lights considering the capacity of the road. Under the condition of given capacity, every car can run through the crossing when the number of cars between the crossings is less than the capacity and the traffic light is green. But no car can run through the crossing when the number of cars exceeds the capacity in spite of the green traffic light. The capacity should be given to make the traffic flow in question dispersed and to increase transportation efficiency. We have controlled several traffic flow cases, for example, the case that the front of the traffic flow is jammed, the case that heavy traffic flow and light flow are crossing at an intersection. The location and the running state of all cars have been calculated at every time-step. The number of cars has been also counted with constant speed, acceleration, deceleration, and stationary condition, respectively. A two-dimensional diffusion equation has been solved on every one hundred time-steps under a periodic boundary condition. The calculated contour lines of concentration of carbon monoxide are described inside the control area. We present three results of this control method compared with the conventional one that did not consider the capacity of the road. The first one is a dispersion of traffic flow and exhaust gas, the second one is a reduction of CO gas, and the third one is an increase of transportation efficiency.