Study On The Influence Of Trucks On Ramp Diversion Of Freeway

The freeway has always played a decisive role in the economic development of our country,and it present different traffic characteristics in every period.In recent years,with the great rejuvenation of the country,the number of the car is growing rapidly especially on the freeway,and the trucks are getting bigger and bigger.Such traffic composition will inevitably lead to new traffic safety problems,especially on ramp diversion area.Therefore,this paper studies the influence of trucks on ramp diversion area to improve the efficiency and safety.Using the research results at home and abroad,this paper analyzes the influence of the different operation modes of the freeway,determines the influence range,geometric characteristics and configuration of the ramp diversion area,sums up the driving behavior and traffic flow characteristics in this area.The main effects of trucks in the ramp diversion area are moving bottleneck and barrier effect,the barrier effect can divided into the occlusion of the road side signs and the influence of the internal vehicle shunting.This paper analyzes the mechanism of moving bottleneck by establishing a model of overtaking,and describes the shunting process of the vehicle with the driver's psychology to systematically analyzes the barrier effect produced by the trucks.In the aspect of road side sign occlusion,first of all,analysis the truck occlusion process dynamically,set up the road side sign occlusion probability calculation model of the ramp distributary area and program with Matlab.The occlusion probability is calculated through engineering examples,and this result shows that probability can effectively reflect the occlusion effect of trucks.Then,give the occlusion probability relationship between car speed,truck speed and truck length,and put forward the improvement measures for signs.In the aspect of the truck moving bottleneck and the influence of the internal vehicle shunting,using Vissim to build 4 and 6 Lane freeway ramp diversion area model to simulation of different traffic conditions.According to the simulation results,analyze and compare the average travel speed and loss time,and discuss the improvement influence of parallel deceleration lane on trucks.