Study On The Effect Of Low Visbility On Freeway Safety In Mountainous Area And Guarantee Technology

The road safety issues on the freeway initiated by the low visibility has caused wide public concern all over the world. The accident rate led by heavy fog trends to increase over the last years. Due to the insufficient visibility, the frenquency of the freeway blockade has augmented. It caused not only lots of fatalities and injuries but also a huge economic losses.The paper have directly analyzed the conditions and characteristics of formation with the fog along the roads under the background of combination of the road engineering, traffic engineering, traffic psychology, the meterology and the statistic knowledges and has researched on the impacts of the low visibility on freeway safety,included the effects of drivers' mental ant physical status,the road circumstances,the traffic benefits, which have heen taken by the low visibility. It also has researched the characteristics of the speed of vehicle on the freeway under the low visibility by collecting the traffic flow data and the visibility data from a freeway in Chongqing,2008. And a initial relational model,which was related of the visibility of meterology and driver's visibility range, has been constructed by passed a series of experiments.The paper have analyzed the maximum safe speed and the minimum safe distance according to the different visibility. A freeway speed limit model has been created, which was based upon the visibility, the friction coefficient,the traffic volume and so on. Finally,the standards of vehicle speed and administration were figurated out under the low visibility situation on the montantic freeway.An analytical commentary about the single vehicle and the risks of the course operation under the low visibility conditon was written with statements,it also made an automobile rear-end model which used the BP neural network with the low visiblity as a basic parameter. At last,it treated deeply the safe gurantee system of montanic freeway operation under the low visibility condition followed by three aspects which were the building of freeway monitor system, the countermeasures for engineering support and the management techniques.This paper was written based on the Yu-Wu freeway.To combine with the existing Monitoring equipment and the proposed increase equipment,set up the fog area Monitoring System of Yu Wu freeway,and gained the fog area speed and car-following distance Management standards of Yu Wu freeway.