Research On Spacing Control And Design Strategy From Tunnel To Main Line Exit And Entrance Based On Operating Velocity

For mountainous expressways with limited terrain and design conditions,it is easy to cause small spacing section between tunnel with main line exit and entrance.The research results have shown that the accident rate of small spacing section is higher than the other sections of the main line,which has threaten the safety of expressway operation and management.Moreover,the design norm and regulations of small spacing sections are still unclear,which is short of clear design requirements and safety measures.In order to provide road designers with reference schemes for new construction and reconstruction of small spacing sections roads,and to improve traffic safety,operating efficiency and capacity of roads,this paper establishes a vehicle speed model for small spacing sections on the basis of vehicle test and investigation.Based on the operating velocity,the minimum spacing between the tunnel with main line exit and entrance is studied,then the spacing control?design strategy and safety measures under various working conditions are put forward.Firstly,the factors affecting the safety of small spacing road sections are analyzed from three aspects: traffic flow characteristics,driver's psychological characteristics and traffic environment.Then,a vehicle test and investigation scheme is designed to collect vehicle data and cross-section traffic flow information.The variation law of longitudinal operating velocity is described from three aspects: tunnel section,diversion process and front section of deceleration lane.At the same time,through the improvement of algorithms,we use the kernel density estimation method,FCM with bisecting K-means combined algorithm,MLE-LM algorithm and Weibull-3 distribution model to study the operating velocity distribution model of the traffic flow section from four dimensions: overall distribution,different traffic flow,different lanes and different proportion of buses,then the operating velocity of each lane is clear.Then,according to the headway distance model under different traffic section flow rate,the driving distance of vehicle waiting for insertible gap under different traffic flow is deeply studied,while the vehicle lane-changing model is constructed,then the minimum spacing model between tunnel with main line exit and entrance considering the most disadvantageous factors is established.Combining with the research results of operation velocity,the spacing values under different design conditions are calculated.At the same time,the accuracy and rationality of the research results are verified by the VISSIM simulation test.Finally,aiming at five different working conditions of spacing values,this paper studies the spacing control and design strategy,and puts forward safety measures from four aspects: improvement scheme of spacing,safety technical measures,driving conditions and safety management.Finally,aiming at five different working conditions of spacing values,this paper studies the spacing control and design strategy,and puts forward safety measures from four aspects: improvement scheme of spacing,safety technical measures,driving conditions and safety management.