Applications Of Visual And Perception Theory In Safety Improvement For The Entrance Of Medium-long Tunnels

With the development of the transport, China has become one of the countries with the fastest-growing and longest channels in the world. After 2008, there were 4,673 road tunnels, almost more than 2,555,500 meters in China,29.2% of which are longer than 500 meters. The entrance of tunnels in the mountain areas, with the complex road line and the sudden change of visual environment, is the bottleneck of the highway, where vicious and serial traffic accidents occurred frequently. As the death rate per million cars of tunnels in China is over 10 times more than developed countries, the safety situation at the entrance of medium-long tunnels is severe and improvement measures need to be taken. In this case, visual and perception theory is applied in safety improvement for the entrance of medium-long tunnels, which is supported by the National Natual Science Foudation of China and Development Projects of Hubei Communications Department.Select representative tunnel entrance as the experimental sections on ShiMan highway. Firstly, the characteristics of road environment, traffic flow and driver visuals at the tunnel entrance are analyzed. Then the time, space, morphological characteristics and reasons of traffic accidents are described. Measure instruments, such as NC200 and Autoscope are used for traffic flow investigation, and manual observation is carried out for data accuracy. According to a detailed investigation on traffic environment, travel speed, driving track, and drivers'visual characteristics at the tunnel entrance, the reasons for high frequency of traffic accidents are analyzed.According to investigation, overspeed is the most commun reason for traffic accidents at the tunnel entrance. With the overspeed rate of 60%, speed control measures should be taken to improve traffic safety at the tunnel entrance. On the road section 300 meters around the tunnel entrance, V85 is lower down to a reasonable range as soon as possible to keep speed constant and reduce speed discrete.Based on driver visual and perception theory, the speed control and lane keeping models are introducted. According to computer simulation results, the calibration and correction of model parameters are maken after driving test on the road. According to the improvement requirements, the speed control edge is put up at the tunnel entrance. After the construction, investigation on travel speed, driving track and drivers' visual characteristics is conducted. Resources show that travel speed has slow down and speed dispersion has been reduced significantly after using the speed control edge, which is coordinated with expected effect. According to method modification and environment validation, the traffic safety improvement measures are reasonable.