Study On Relevant Technical Indexes Of First-grade Highway

The highway transport system is gradually improving in China,and as the main infrastructure of the transportation industry,highway occupies a large proportion in the whole transportation system.The construction scale of the first-grade highway is gradually expanded,but the accident rate of the first-grade highway is high.Since there is not systematical researches on the access and collector-distributor lanes of the first-grade highway in China,the current research results are far from meeting the needs of traffic safety.Therefore,from the perspective of traffic safety and traffic smoothness,it is necessary to study the relevant technical indicators of the access of the first-grade highway.Based on the basic concept of the entrance and the difference between the entrance and the flat intersection,this paper analyzes the typical problems existing in the access of the firstgrade highway in China,and puts forward the research on the representative models of the access and the intersection of first-grade highway;And with reference to the research results at home and abroad,the influencing factors of setting the access on the first-grade highway are analyzed,and the research scope of this paper is defined.From the perspective of preventing the vehicle from rushing into the main line at a higher speed after the slope,it is proposed to set a transition between the main line and the access road with a large slope.According to the level of the intersecting roads,the geometric parameters of the roads connected to the first-grade highways are studied from the aspects of reducing the accident rate caused by the access.And this paper puts forward the recommended values of key indexes such as inlet Angle,inlet width and turning radius,itd slope and length.From the point of view of reducing the interference caused by the vehicles at the access and entrance to the direct vehicles on the first-class highway,it is proposed to set up the collcterdistributor lane at the access of the first-grade highway.Analysing the various situations of the setting the collcter-distributor lane and the composition and form of the collcter-distributor lane,the design speed of the collcter-distributor lane at the access of the first-grade highway is recommended;Based on the influence of access on the traffic capacity of the main line,the distance between the access and the density of the access,a model is established to analyze and calculate the conditions for setting up the distribution lane;and the conditions and the way of setting up the collcter-distributor lane between two intersections on the first-grade highway are analyzed.The technical indicators of the collcter-distributor lane are studied.The influencing factors of the acceleration and deceleration lanes and cross sections are analyzed.The key parameters of the acceleration and deceleration lanes and the cross-section are calculated,and the recommended values of the relevant indexes are put forward.The research results of this paper have great significance to make up the relevant technical indicators of the first-grade highway access and the setting of the collcter-distributor lane in China,and provide technical support for the reasonable setting of the access and the collcterdistributor lane of the first-grade highway.