Analysis Of Traffic Safety Characteristics Of Continuous Long Downhill In Extra-long Tunnel

Extra-long tunnel has the characteristics of monotonous environment and is easy to make drivers tired and fretful.Once traffic accidents occur,it will cause serious economic losses and social impact.Based on the project of "Research on Traffic Safety Improvement of Wanxichong Extra-Long Tunnel(8.1 km long tunnel)on Fuyi Expressway",this paper takes six continuous extra-long downhill tunnels of G65 Baomao Expressway as the research objects,and through field test and indoor simulation experiment,the law of speed change and driver’s response time change of continuous extra-long downhill tunnel are studied systematically.The main contents and achievements of this paper are as follows:(1)The differences between continuous long downhill roads and continuous long downhill tunnels are compared and analyzed from three aspects of people,vehicles and tunnels,and the characteristics of tunnel traffic accidents are obtained based on the analysis of tunnel traffic accidents in Chongqing from 2010 to 2016.On this basis,the influence of driver factor,tunnel environment factor and vehicle factor on traffic safety of long downhill tunnel is analyzed,which provides a good basis for the study of traffic safety characteristics of long downhill tunnel.(2)Taking six tunnels in Wulong section of G65 Baomao Expressway as the object,the speeds of three types of vehicles,including cars,coaches and trucks,with multiple sections in the longitudinal direction of six tunnels were measured.The relationship between vehicle speed and the distance from the tunnel entrance and slope rate was obtained through data processing and analysis in the later period.Based on the trend surface theory,the function model between truck running speed and distance from tunnel entrance and slope rate is established,which provides a reference for vehicle speed prediction in continuous long downhill tunnel.(3)Combining with the self-compiled response time measurement program,a test platform for response time measurement based on dynamic environment has been developed independently,including scene projection,driving simulation,stimulation output and data acquisition functions,which provides a good indoor test platform for the study of traffic safety of extra-long continuous downhill tunnel.(4)Based on the indoor response time measurement test platform,the response characteristics of drivers in continuous extra-long downhill tunnels are studied by simulating the brake taillights with random red spot with direction markers.The relationship between the response time of drivers in continuous long downhill tunnels and the distance from the tunnel entrance,slope rate and running speed of tunnels is obtained.The regression function model between the reaction time and the distance from the tunnel entrance and the running speed is established,which provides a reference for the reaction time prediction of the driver in the continuous long downhill tunnel.(5)Combining the speed prediction model with the driver’s response time regression model,the parking sight distance calculation model of the extra-long downhill tunnel is revised from the point of view of kinematics.(6)Based on the experimental results and the characteristics of the continuous extralong downhill tunnel,the traffic safety improvement measures for the continuous extralong downhill tunnel are proposed from the aspects of tunnel design parameters optimization,light environment improvement measures,speed control measures,driver visual guidance and other traffic safety measures.Through this study,the traffic safety characteristics of the extra-long downhill tunnel are obtained,which provides some reference value for improving the traffic safety of the extra-long downhill tunnel.