Moderate Expressway Vehicle Flow Control Under Unfavorable Weather Condition

The safety of expressway operations dues to unfavorable weather significantly, particularly in the extreme unfavorable weather conditions. Anciently, as economy technique and facilities as well as expressway management fall behind, the expressway will be closed down, this will lead heavy economic losses to vehicles and expressway departments. How to assure the traffic capacity and traffic safety under unfavorable weather have become the issue of social safety and economy that every country values.This article does the studies as follows:summarize how the developed countries carry on a series of researches on the management and control of expressway under unfavorable weather and the shortages existing in expressway management in our country; points out the characteristics of accidents, analyzes the effects of the unfavorable weather on road safety and function of expressway; on the basis of present traffic control level of the expressway, promote expressway traffic safety control system composed of environment information collect system, traffic driving safety system, intellectively information release system, emergency control system and management system introduce the functions and components of each subsystem; this article will bring forward the cars stand in a line waiting to enter expressway on the basis of the car following theory, and combine traffic safety with safety interval distance, reach a reasonable formula for the speed limit under the unfavorable weather, establish the relation between visibility and the expressway safety speed; at last, we establish expressway traffic safety facilities system actuality of our country, and make study of concretion evaluating indicator standard of criterion, indices analyzing and approaching named Fuzzy Comprehensive Evaluation based on Analytic Hierarchy Process (AHP).The application of the achievement in this paper is helpful to strengthen the expressway safety of non-stop operation under the unfavorable weather, for the settlement of expressway safety to provide an effective means of control according to roads, traffic and weather conditions, strive to not close down the expressway and improve the efficiency of road utilization, so as to attain optimal economic and social benefits.