Research Of Traffic Flow Operating Characteristics And Safety Control Methods Based On The Variation Of Visibility

The rapid development of the transportation industry puts forward higherdemand and new challenge for the transportation capacity of the regionaltransportation system and traffic safety of road. However, the type and grade ofurban road are complex, so as the road network and function. It is necessary toanalysis and study the characteristics of speed variation under low visibility for thepurpose of reducing the number of traffic accidents. Then it will ensure that thevehicles drove safely and efficiently on urban roads, especially the running underlow visibility.The paper contents are mainly according to the traffic flow operatingcharacteristics and safty control methods under the visibility variation. Beginningwith the practical survey data of vehicle speed, the study use the statistic methodsto dispose the survey date, and analysis the traffic flow characters by CA (CellularAutomata) model. The characteristics of speed variation under different visibilitiesare paid attention among studying the traffic flow characters under variousvisibility, as well as the speed characters in different visibilities and different roadsection (numbers of lane). Control methods of traffic saftey will be proposed at theend of the paper, Specific contents are as follows:Firstly, the existed problems will be put forward after collecting and finishingthe previous study. Three parameters of urban traffic flow, which are speed, flowand density, are mainly analyzed, and the major factors are put forward. Thencar-following theory model, hydrodynamics model and CA model will be discussed.Secondly, the changing character of driver’s dynamic view under differentvisibility will be introduced. And the relationship between dynamic sight and theaccident rate, the visibility and dynamic sight, and the visibility and speed identifywill be dwelled on. What’s more, the influenced factors of the driver’s visualcharacters would be analyzed.Thirdly, CA model which fits all kinds of studying conditions will be built andthe simulated result will be discussed in detailed, including speed dynamiccharacteristics of the same road section under different illumination and speeddynamic characteristics of different road section under the same illumination. TheSPSS would be applied to statistic analyzing of survey data. Then the changing characters and speed limits under different visibilities and fundamental diagrams ofthree traffic parameters under low visibilities will be put forward.Finally, the relationship between the speed limit values and accident ratesunder various visibilities will be introduced. The basic traffic characters of human,vehicle and road, and necessary measures for safety driving under low visibilitieswill be studied.The results of study will provide effective and practical theoretical basis fordynamic speed limits under different visibilities.