The Study On Car-Following Performance Of Drivers And Risk Of Traffic Safety At Low Illumination Environment

For the reason of insufficient light condition, low illumination environment has significant effect on the physiological and psychological characteristics, especially on the visual characteristics of drivers, and thus affects road safety. To study the relationship between driver’s recognition time and environment illumination as well as car speed at low illumination environment, then study the relationship between the brake response characteristic of car and environment illumination, and also the risk of traffic safety under condition of different environment illumination, based on the National Natural Science Foundation of China "Operation Characteristics of Road Traffic Flow When Environment Illumination Change and Its Influence Mechanism to Traffic Safety(No.51308177)", real vehicle test was designed to obtain driver’s recognition time of six kinds of color under condition of different illumination and different car speed. After obtaining the data of driver’s recognition time, some relative statistical analysis was conducted, and the results show that there is no linear relationship between driver’s recognition time and environment illumination and also between driver’s recognition time and car speed. Moreover, both illumination and car speed have significant effect on driver’s recognition time of six colors while the significance level α is 0.05, besides, the influence of illumination on red sighting targets is most significant in all sighting targets of six colors and the influence on blue targets is least significant, while the influence of car speed on black sighting targets is the most significant and the influence on yellow targets is the least significant.Based on the previous statistical analysis, the binary function model of driver’s recognition time and environment illumination as well as car speed was built by data fitting of driver’s recognition time and then the car braking distance model considering driver’s recognition time was deduced. Furthermore, the change law of car braking distance with the influence of illumination was analyzed and numerical simulation method was taken to study the change law of traffic accident rate with the influence of illumination, and the results show that the braking distance of red, yellow and blue sighting targets shows a trend of continuous decrease while environment illumination increases. Moreover, the braking distance of green, white and black sighting targets shows decreasing trend after increasing while environment illumination increases, thus a maximum braking distance could be found.Both environment illumination and object color have great effect on the risk of traffic accident. When the illumination is more than 5001x, the accident risk brought by green obstacle is highest in obstacles of six colors, when the illumination is more than 3001x, the accident risk brought by black obstacle is highest and red obstacle with lowest accident risk in obstacles of six colors except green obstacles. When the illumination is less than 3001x, the recognition of obstacles of different colors appears a large fluctuation, therefore, the illumination 3001x is a critical value at which the driver’s recognition features to obstacles of different colors. When the illumination is less than 501x, the accident rate of black obstacles is the highest and the accident rate of green and white obstacles is very low. In addition, the results also show that the difference of accident rate among obstacles with different color at normal illumination is obviously greater than the difference at low illumination, and the identification ability to different colors at low illumination is relatively weak.In the end of the article, specific advice to speed control and the design of traffic safety facilities was proposed based on the previous results.