Study On The Evaluation Method Of Traffic Safety Management Measures For The Long And Steep Downgrades Of Mountain Expressway

In recent years,highway construction in China has entered a new stage with the rapid development of national economy.The traffic safety of the long and steep downhill sections of mountain highways has gradually become the focus of industry research.The complex traffic environment of the long and steep downhill sections of mountain highways is a great challenge to driving safety.And some long and steep downhill sections have even been accident-prone locations.Driving speed management and escape lane setting are two common traffic safety management measures for long and steep downhill sections.Reasonable speed limit management plan and the setting of avoidance lanes can effectively reduce the number of traffic accidents or reduce the casualties and property losses caused by accidents to a certain extent.In the first part of the thesis,according to the survey data of a long and steep downhill section in the southwest mountainous area in China,the traffic characteristics of the long and steep downhill section is analyzed in terms of people and vehicles.After that,based on the total number of accidents and accident locations on the long and steep downhill sections of mountain highways,both the relationship between traffic accidents on the long downhill sections and the accidents on the whole line,and the trend of the change of accident locations on long and steep downhill sections are quantitatively analyzed.Furthermore,the traffic safety management of the long and steep downhill section of the mountain highway is investigated from the two aspects of the speed management and the escape lane setting.By analyzing the adoption standards and principles of the speed limit,a judgment method using the coordination of operating speed and the consistency of the speed limit with the expected speed is proposed to evaluate the rationality of the speed limit plan,and the trend of the number of accidents before and after the adjustment of the speed limit plan is also studied to analyze the effectiveness of the adjusted speed limit plan.Through analyzing the relevant principles of the location of escape lanes,an evaluation system is established,in which the temperature rise of the brake hub of a large truck is utilized to evaluate the location of avoidance lanes,and the accident analysis method is adopted for judging the utilization of escape lanes.Finally,according to the established evaluation system,the speed limit management plan and the setting of escape lanes in the downhill direction of the long and steep downhill sections of No.1 and No.2 of a mountainous expressway in southwestern China are evaluated.Based on the evaluation and analysis,corresponding improvement measures are also proposed.It is concluded that the traffic accident characteristics and traffic characteristics of the long and steep downhill sections of mountainous highways are studied,which can provide a certain reference for the basic research on the traffic safety of the long and steep downhill sections.The established evaluation system can be used as reference for design and operation in practical issues such as formulating speed limit standards and adding escape lanes.