Study On The Traffic Safety Of The Continuous Longitudinal Slope Sections Of Expressway In Southwest Mountainous Area

With the rapid development of the expressway construction in China,the number of expressway in mountainous area has been increasing in recent years.However,the unique terrain,landforms and geological conditions in the mountainous area made the mountainous expressway have many continuous longitudinal slope sections,presented as a high braking risk for the large truck on the continuous downgrade sections,the reduction of the capacity and the level of service of the continuous upslope sections,which influenced the traffic safety of the whole project.Therefore,this thesis was based on the preliminary design data of expressway in Yunnan province,through consulting the related research contents both at home and abroad,the safety of continuous longitudinal slope sections in this project was studied,which based upon the braking risk on the continuous downhill sections and the level of service of the continuous uphill sections.First of all,On account of the preliminary design data of the supported expressway project,by analyzing the natural geography and traffic composition of this project,the traffic safety of the large truck was determined to be the focus.Referring to the research results of slope and slope length at home and abroad,the determination standard of continuous downhill sections of the project was determined,and the continuous downhill sections of this project was defined by this standard.Secondly,based on the analysis of safety in operation of large trucks on the continuous downhill sections,the temperature prediction model of brake drum and the temperature judgement standard of large trucks in continuous downhill sections were determined,according to the change of the temperature of the brake drum of the large truck,the expressway alignment and the structure distribution of the continuous downgrade sections,the traffic safety of the continuous downgrade sections was studied.Then,based on the traffic volume and traffic composition of the project,the level of service of the continuous uphill sections was determined,and based on the operating speed model,the speed of the large truck on the continuous uphill section was determined,from the two angles of the operating speed of the large trucks and the level of service of the continuous uphill sections,the traffic safety of the continuous uphill sections was studied.Finally,the traffic safety guarantee technologies of the continuous longitudinal slope sections at home and abroad were summarized from the three aspects of active safety guarantee technologies,passive safety guarantee technologies and traffic management countermeasures respectively.The conclusion of this thesis is to ensure the traffic safety of the supported expressway project,and to provide useful experience for the future construction of continuous longitudinal slope sections of mountainous expressway.