Research On Risk Assessment And Clear Zone Design Method Of Freight Vehicles Roadside Accidents On Low Grade Highway

With the development of highway freight transportation,the number of roadside accidents involving trucks is increasing year by year.Due to the poor road surface condition,curve radius,longitudinal slope and other linear conditions,as well as the truck body length,poor driving performance,heavy weight and other related factors,truck accidents involved in heavy and large accidents,and roadside accidents in the occurrence of a large proportion of accidents,resulting in a high death rate.Based on the analysis of the causative mechanism of the truck side accident system on the low grade highway,this paper constructs the probability prediction model of truck side accident on the low grade highway.The risk assessment method of truck side accident on low grade highway is put forward through the research of passenger injury in truck side accident on low grade highway.By exploring the main factors that affect the design of low grade highway side clear zone width,the calculation method and setting conditions of low grade highway truck side clear zone width are put forward.The research results are helpful to enrich the theories of highway safety design and traffic management,and provide decisionmaking basis for the traffic management department to improve the highway freight transportation infrastructure,so as to improve the level of highway transportation safety.First,PC-Crash software was used to conduct simulation tests on six risk factors of roadside accidents,including circle curve radius,vehicle speed,longitudinal slope,ultra-high transverse slope,road adhesion coefficient,vehicle type(light truck,heavy truck).Binary Logistic regression analysis was used to identify significant risk factors of roadside accidents,and the probability prediction model of roadside accidents of trucks on low grade highway was built.Based on the probabilistic prediction model,the cumulative frequency curve method is used to obtain the probability threshold of the potential multiple points of truck side accidents on low grade highway,and the identification method of truck side accidents on low grade highway is proposed.Secondly,by setting different curve radius,slope slope,exit speed and subgrade height,PC-Crash simulation software was used to carry out road side simulation test of light truck and heavy truck driving.Taking ASI as the occupant injury evaluation index,through analyzing the relationship between each test parameter and occupant injury evaluation index,an occupant injury evaluation model based on ASI was constructed for the linear section and curve section of low-grade highway.By defining the ordered data samples of ASI and using Fisher’s optimal segmentation method,the reasonable evaluation level and ASI threshold of roadside accident severity were determined,and the evaluation standard of roadside accident severity of low grade truck on highway was proposed based on ASI.Based on this,a risk assessment method for truck side accidents on low grade highway is proposed,which considers accident probability and accident severity.Finally,by exploring the main factors affecting the design of roadside clear zone width,different exit speeds and circular curve radii were set to carry out the roadside simulation test of light trucks and heavy trucks,and record the movement trajectory of each test vehicle after entering the roadside,and propose the calculation method of roadside clear zone width of lowgrade highway trucks.By considering subgrade height,road shoulder width and the suggested value of road side clear zone width obtained by the research,the setting conditions of road side clear zone are studied.For the sections that meet the conditions of roadside clear zone setting,a calculation model of safety benefit and engineering cost is constructed.Based on the safety benefit-engineering cost,the setting condition of road side clear zone of low grade highway freight vehicles is put forward.