Urban Road Traffic Flow Evolutionary Based On The Influence Of Accident Vehicle

The research of urban road traffic flow evolutionary under the influence of the accident vehicle has the important theoretical significance and practical value to provide support for alleviating traffic congestion. The previous research of traffic flow evolutionary were based on different duration of the accident vehicle or different length of conflict zone.But those studies did not discuss to combine this two situation to research the traffic flow evolutionary under the influence of the accident vehicle.Thus, based on the urban two-lane and three-lane road traffic flow characteristics by accident vehicle, the cellular automaton traffic flow model is built. By a numerical simulation, a flow diagram, a space-time diagram, density diagram and velocity diagram are given to analyze the regularity of traffic flow evolutionary under different accident duration and different length of conflict zone. The major works and achievements of this study are as follows.According to the situation of two-lane with R lane blocked,the research by the analysis of numerical simulation finds that the road traffic will be in a state of severe congestion when the traffic flow is in the state of free flow and Td reach to 15 minutes. When the traffic flow is in the state of saturated flow and Td reach to 5 minutes, the road traffic will be in a state of severe congestion,and if LB is more than 10 cells, density will be inverse between L and R lane, at the same time, the density increase to 0.8.According to the situation of accident vehicle in urban three-lane, it is found that when the traffic flow is in the free flow state if R lane blocked and Td reach to 15 minutes, the average speed of vehicle is lower than 20km/h but greater than 10km/h, the road traffic is in the congested state. When the accident vehicle occupied the M lane and LB is more than 6 cells as well as the average speed of vehicle is less than 30km/h but greater than 20km/h, the road traffic is in the congested state. When the accident vehicle occupied the M and R lane and LB is more than 10 cells, through the numerical simulation to found that the average speed of vehicle is less than 10km/h, the road traffic is in the severe congestion state. When the traffic flow is in the state of saturated flow and Td≥5, the road traffic is in a state of congestion in these three situation. At the case with one lane blocked by accident vehicle and LB≥ 24, density is close to 0.7. If two lanes are occupied by accident vehicle, the density of this situation is greater than the situation of one lane blocked by accident vehicle.