Study On Emergency Traffic Organization Evaluation Of Freeway

A variety of traffic accidents happened on the highway take up part of lanes. For this reason, the capacity and the service level of the road will be reduced. According to the experience, it is not reasonable to deal with the problem of heavy traffic by increasing road supply ability and withholding the traffic demand. Besides, the other problem that should not be ignored is that the management is on the low level in present. Therefore, taking measures of the emergency traffic organization reasonably is regarded as one of the best method to solve the traffic congestion.The traffic flow in the accident section of highway is analyzed. Based on the characteristics of the upstream traffic flow, the influence area is divided into protected area, control area, and buffer area. Then the measures of emergency traffic organization are proposed for the different areas. Taking Shihuang highway as an example, highway network and model of traffic accident are established by using the software of VISSIM. The change rule of average delay and queue length in different traffic flow, proportion of the heavy cars, and the duration of the accident are analyzed. The emergency measures such as ramp control, traffic split-flow,speed-limited methods and the use of opposite lane are proposed based on the model analysis. The effects of the four traffic organizing methods are verified by VISSIM.Through the analysis of the cell transmission model, variable speed-limit control model can be built by applying the relationship between density and traffic flow.Based on this theory, three methods such as speed limited in different section,different section and the type of vehicle, and different interval of time are proposed.Besides, VISSIM is applied to verify the effects in three kinds of speed.According to the characteristics of Shihuang highway, index to evaluate capacity of the road network are selected and the model to evaluate the response ability of highway network is established. The method of fuzzy comprehensive evaluation is used by quality and quantity to evaluate the model. These analyses draw the conclusion that the road network has good performance on applicability.