The Method Of Adjacent Speed Limit Sections Dividing And Combining For Freeway Based On Safety And Efficiency

Freeway is one of the most important component in the whole road traffic system,how to realize which functions of safety and comfort,efficiency and economy is one of the key subjects for all circles in society both at home and abroad,especially in transportation area.Speed limit is one of the most common methods for freeway management to achieve all above functions.And speed limit sections are often designed for many freeway when they are confined with the linear constraints,and practice has proved that reasonable speed limit and speed limit sections can promote raising the level of safety and efficiency,however the inappropriate speed limit will be exactly the opposite.Excessive speed limit sections will not only reduce the rate of road speed limit complying,and affect the level of road safety,but also cause drivers to frequently accelerating or decelerating,and influence the convenience of driving operation,as well as the comfort of riding and the economical efficiency.This article is supported by traffic science and technology program——The Speed Management of Freeway Based on the Safety and Efficiency(No.14-32R)of Shanxi province transportation department,which based on the antecedent study in speed limit and speed limit sections dividing and combining both at home and abroad,the author expose a further analysis.Firstly,defines the connotation of safety and efficiency,then base on safety and efficiency evaluation index system and index selection principle put forward the safety and efficiency multimetric index exponent evaluation model,and explicit the unity of opposition relation between safety and efficiency and speed limit,which provide a evaluation basis for the rationality of speed limit section dividing and combining,Secondly,refer to existing speed limit rules and automotive speed table in our country,determining the minimum speed limit sections length corresponded to the designated different speed limit values based on drivers’ physiological and psychological safe distance as well as the minimum speed limit signs’ front distance and transition distance.At last,VB programming language is used for transforming the algorithmic model into Personal Computer exercisable interface according to the proposed method of adjacent speed limit sections combining for freeway based on the minimum loss of time model in this paper.Additionally,design a software —“speed limit zones division and combination optimization system for freeway”,which realize the optimization setting of speed limit sections dividing and combining based on safety and efficiencyFinally,take one of freeway in Shanxi province for instance,we apply the proposed theory in this article on whose initial speed limit setting,then after the optimization compare the safety and efficiency indexes outputted by VISSIM simulation with the initial one,and verified the resonability and validity of the model.