Research On Safety Evaluation Of Highway Interchange In Mountainous Areas

The Road interchange is an important node in the design of expressway,which complements the requirements of the intersection of road space and the change of traffic direction.The selection of location and form of large-scale interconnection is often affected by many factors,such as topography,geology,planning,environmental sensitive points,main line index of intersecting road and bridge-tunnel structure.However,the environment,terrain and geology of mountain expressway are especially complicated,so it is difficult to meet all the restrictions.Various factors need to be considered in the design,and the function,form,scale,cost and specification requirements need to be repeatedly weighed among the factors of intercommunication,often need to give up or sacrifice some indicators to meet the needs of other aspects.Designers should not only fully grasp and apply the specifications,but also take measures according to local conditions in combination with the mountainous terrain characteristics,and choose the comprehensive and optimal form of interchange,so that the expressway interchange can not only meet the needs of safe operation,but also coordinate with the local natural environment.The Lugao junction of the Jinyang to Ningnan section of G4216 expressway is characterized by narrow engineering site,high mountain and deep valley,sharp cutting,steep terrain,unique interconnection location,complex interconnection form and low linear index.In the stage of construction drawing design,through optimizing the form of interconnection,the ramp index is improved,the project cost is greatly saved,the construction difficulty is reduced,and the implementation of the scheme is ensured.But the optimization of the design has also brought some problems,mainly reflected in the individual indicators break through the requirements of the current industry norms and rules.In view of the lack of research on violation indexes,difficult projects and directional countermeasures in the existing safety evaluation methods,it is necessary to verify the results of the safety evaluation of Lugao hub interchange through other methods.In this paper,first of all,according to the current safety evaluation standard requirement to safety evaluation of reed draft hub exchange,analysis of existing problems,and then combined with the feature of environment,design index and safety evaluation of key indicators,such as different index of the coupling coordination degree analysis,reoccupy coupling coordination analysis verify the result of conventional evaluation of Ann,and put forward improvement Suggestions according to the results of the comprehensive analysis.In this paper,the coupling coordination degree method is applied to the safety evaluation of highway engineering projects,which provides a new idea for the safety evaluation of the project,and explores the new usage of the coupling coordination degree method,which can provide a reference for the safety evaluation of interchange.The main research contents of this paper are as follows:(1)Discussion on interchange indexes of mountain expresswaysThe index requirements of the interchange and the distance between the interchange and other special structures are analyzed.Combined with the consistency evaluation content of interchange form,the basic connection relationship and exit consistency between main line and interchange are analyzed.The setting standards of traffic safety facilities are analyzed,including the guardrail on the whole road,the central anti-dazzle facilities,the road traffic directions and guidance signs,the traffic lines of different sections and the protrusions of road signs,the contour marks around the guardrail,the highway emergency stop belt and other safety and rescue facilities.(2)Analysis of environmental characteristics and safety characteristics of mountain expressway interchangeThis article summarize the characteristics of mountainous highway interchanges,and the basic situation of the research section are analyzed in detail,put forward the unique features of natural geographical environment of mountainous area,mainly including natural geographical environment and terrain features,climate differences,and because of the mountains and bring bad geological environment,such as terrain,sections of the interchanges and connected to the main line of road traffic and transportation were investigated.(3)Safety analysis and improvement measures of mountain expressway interchange sectionAccording to the parameter content of safety characteristic evaluation,some indexes were selected to construct the entropy weight matter element model and coupling coordination relationship model for safety evaluation of interchange sections.Analysis build index data of different evaluation level and results of different types of coupling coordination degree,and in accordance with the specification of interchanges road safety evaluation of the evaluation results for validation,combination of entropy matter-element model and coupling coordination model test and verify the reliability of conventional Ann evaluation results,and verified the coupling coordination degree method is used to evaluate the feasibility of safety.According to the evaluation results of the model,corresponding improvement suggestions are put forward to improve the safety level of the design indexes of interchange sections of mountain expressways.