Study On The Freeway Speed Limit Under Traffic Incident

Traffic incident is a usually problem in the use and construction of highway, which has amarked impact on the drivers. And it may bring a severe secondary accident so that themotorway service performance compromised.Domestic and international transportationdevelopment experience and lessons that solve the problems under the traffic incident, theneed to develop reasonable and proper transportation organization, take a scientific limitedspeed, and set effectively limited speed signs in the position. As a result, these measures makemaximize the use of transportation resources and better services to the driver. This paperfocuses on the characteristics of traffic incident of freeway, combining common trafficorganizational forms, and solves the problems that what the limited speed acquired when thetraffic incident occurred in the basic and special position of freeway and where the speed limitsigns set proper. Then give some instructions to traffic engineering.The contents of this dissertation are as follow:Firstly, the traffic incident affected zone has been divided and a specific calculationmethod of length of every zone has been given Events area is divided into sections: warningzone, the upstream transition zone, buffer zone, the work area, the downstream transition zone,termination zone. Then the paper analyzes the relationship of the degree and dispersion ofvehicle speed between the safeties of freeway.Secondly, Research on the basic position of freeway limited speed problem withsimulation study. The characteristic of the position of freeway is analysis including highwaycapacity, the characteristics of vehicle change lane in merge area and the security clearance ofchange lane. If the vehicle change lane with critical distance, this behavior will identity aschange-lane conflict. If the accelerated speed and distance between vehicles is in somedifference, this situation wills identity as crash conflict. The more traffic conflicts that showsthe more insecure and the greater the capacity reduction indicates the lower traffic efficiency. Under these conditions established cellular automata microscopic simulation model, it studyon the value of limited speed in four-lane and eight-lane freeway with different trafficorganizational forms, and the recommendation limited speed is given.Thirdly, Research on the special position of freeway limited speed problem, includingramp, tunnel and long downhill. The first section gives the definition of special points, andthen point out the safety of vehicle change lane and the braking and security clearance. Finally,cellular automata simulation model is established under the traffic organization form ofspecial position, give the different speed limit value in different slopes and different highwaycapacity and the speed limit value in ramp and tunnel.Fourly, Study on where the speed limit signs set is proper. First, the type of speed limitsigns were divided and pointed out the similarities and differences in the construction workzone and traffic accidents about speed limit signs. Second, under the driver’s physiologicalfactors analyzed the impact of speed limit signs for the driver. Then put forward specific pointin the basic sections and special sections position, the final position settings for speed limitsigns and application of the model to verify the validity.