Study On Speed Limit Improvement Of Six Lane Expressway Based On Safety/Traffic Efficiency

With the continuous development of Chinese economy and the continuous progress of society,the public’s requirements for fast travel on roads are getting higher and higher.Some provinces have begun to explore the construction of "super high-speed" 6/8-lane expressways with good linear conditions and high traffic demand to meet the needs of higher vehicle speeds and achieve higher traffic efficiency.However,the relevant research on the road conditions,speed limit plan,speed limit implementation countermeasures and security assurance measures of speed limit increase is not perfect,and it is difficult to support the effective improvement of expressway traffic efficiency.This paper takes six-lane expressways as the object.First,based on the relationship between speed and driver’s traffic characteristics,this paper proposes a maximum driving speed that comprehensively considers visual characteristics and comfort as the maximum constraint of speed improvement;considers driving stability,safe braking and driving comfort,combining VISSIM simulation technology to explore the influence of horizontal and vertical lines and traffic conditions on driving speed,and propose road conditions for speed limit increase;then according to the principle of lane function division,propose lane function division methods under different proportions of equivalent slow vehicle;Carry on the simulation of the traffic flow state under different speed limits,select the conflict rate less than 3.2 as the safety constraint,E=qvt as the efficiency evaluation function,and propose a method for determining the speed limit increase value,and on this basis,a six-lane expressway is proposed Speed limit promotion plan and implementation method.Finally,based on the analysis of the impact of speed increase on the design/layout of traffic signs,the design and layout methods of traffic signs after speed increase are proposed,and the construction content of smart operation scenarios is proposed based on perspective of driving safety.The thesis carried out research on the speed increase of six-lane expressway,obtained the road conditions,the speed limit plan and implementation method and the safety guarantee countermeasures of speed limit increase,which enriched the technical system and research methods of the speed limit increase of the expressway.It plays an important role in improving the speed limit scientifically,improving road traffic efficiency,and ensuring driving safety.