Study On Driver’s Light And Dark Adaptation Change Law In Section Of Expressway Tunnel Group

In recent years, Chinese expressway has developed rapidly, having longer mileage andmore tunnels. However, with the characteristics of intensive tunnels, short separation distanceand dramatic changes in light environment on the import and export of tunnels, tunnel groupin mountain expressway make driving conditions change frequently in a short period of timeand cause great impact on driver’s psychological and physiological, having higher securityrisks. Literature shows that most of the road tunnel accidents are related to the driver. Driversobtain traffic information mainly from visual access when driving. Light and dark adaptationdrivers experiencing in tunnel group seriously affect drivers’ visual perception of trafficinformation, resulting in short-term visual ‘blank’ which can easily lead to accidents.Based on the research on environmental characteristics of expressway tunnel group,combined with statistical analysis on the433typical accidents in expressway tunnels, spatialand temporal distribution and main reasons of traffic accidents were analyzed and the pupilarea was selected as the characterization parameters of drivers’ light and dark adaptationaccording to the driver visual adaptation theory. Using eye tracker to record driver pupil sizedata, light meter to measure the ambient light value and other relevant equipment to recordother related parameters, vehicle experiments was conducted on actual road. The exponentrelation between ambient light of tunnel E and the distance from the tunnel entrance dwas found through single variable non-linear regression analysis. Test road was divided every50m and the pupil area data was analyzed to ensure driver pupil size variation law on theimport and export of a single tunnel segment. Meanwhile, using the quantitativemathematical modeling method, the relationship between driver pupil area Q and ambientlight of tunnel was analyzed and a linear function relationship between ln(Q/E)andln(E)was found and built. Finally, the model of relationship among pupil size change rateVQ, vehicle speed v, ambient light of tunnel and the distance from the tunnel entrance wasestablished.According to the environment light change law inside and outside tunnel entrance,expressway tunnel was divided into ‘3section’. Aiming at the alternating process of the lightand dark adaptation which drivers experienced in the tunnel group, the method of ‘six smallsection’for the expressway group tunnel division was put forward. Driver’s pupil size changelaw was analyzed in the typical tunnel group located in the upward direction of Xi-Zhasegment of the Bao-Mao expressway. The conic model between the length of the tunnel connection and the biggest difference of driver’s pupil size, which representing drivers’visualload, was built. From the requirement of drivers’ psychological and physiological,suggestions and measures were proposed to improve ambient light in tunnel group.