Reliability Analysis And Verification Of Operation Safety Of Typical Highway Sections

The enormous casualties and economic losses caused by highway traffic crashes have become a considerable public concern.Analyzing the reliability of highway safety and then proposing targeted countermeasures are effective means to improving highway safety performance.By simulating the coupling effect of human-vehicle-highway during the process of driving,vehicle dynamics simulation can characterize vehicle dynamic parameters,thus having become a potential tool to evaluate highway safety performance.However,the simulation of vehicle dynamics simulation has certain limitations.For example,the influence of heterogeneity among different drivers(driver’s gender,age,driving style,etc.)on vehicle operating speed and the response difference(perception and reaction time)of different drivers to factors such as road characteristics are ignored.Based on the stochastic theory,the uncertain inputs of different drivers(e.g.,vehicle operating speed,perception and reaction time)can be formulated as random variables that follow a certain probability distribution,and the possible failure modes that may cause vehicle crashes are considered as the research object.The safety of the highway is analyzed and evaluated through calculated failure probability.This method can remedy the limitation of vehicle dynamics simulation to a certain extent,and provide a new perspective for the reliability analysis of highway safety.In this paper,the reliability analysis of highway operation safety based on the vehicle dynamics simulation perspective(defined as the reliability analysis of certain parameters)is considered as the benchmark.And the reliability analysis from the perspective of uncertain parameters is introduced into the operation safety research of two typical sections: long and steep downhill and curve sections.The highway safety indicators from the two perspectives are verified and compared by establishing a relationship between the highway safety indicators of the two perspectives and traffic crashes.The specific research contents of reliability analysis of highway operation safety from the two perspectives are as follows:(1)Reliability analysis of highway operation safety based on vehicle dynamics simulation.The vehicle dynamics simulation platform for small-sized vehicles and heavy trucks is built based on Car Sim/Truck Sim.Through the simulation platform,the impact of highway design factors including pavement roughness(the factors of pavement roughness that are often ignored in highway safety research are considered)on the driving safety of small-sized vehicles and heavy trucks is studied.And the safety of unfavorable curve sections and downhill sections corresponding to the limit value and general value of highway geometric alignment in highway engineering technical standards are analyzed.(2)The reliability analysis of uncertain parameters is introduced into the operation safety study of long and steep downgrade sections.Firstly,the main failure modes that may lead to traffic crashes of heavy trucks on long and steep downgrades are analyzed,and the limit state functions of each single-mode failure are developed.A multi-mode failure system is established based on single-mode failures.Secondly,the single-mode failure probabilities of heavy trucks on 137 long and steep downhill sections are solved by the Monte Carlo method,and the multimode failure probability of the failure system is solved by the wide bound method.Thirdly,the single-mode failure and multi-mode failure of 137 long and steep downhill sections are analyzed,and Poisson models considering single-mode failure probability and multi-mode failure probability are developed respectively to examine and compare each single-mode failure and the failure system.Then,to address the unobserved factors described in the reliability analysis from the perspective of uncertain parameters,this thesis also develops the random effect/random parameters Poisson models to explain the heterogeneity of factors not observed in the crash data.Finally,based on the optimal model in the above crash prediction models,the relationship between multi-mode failure probability and operation safety of long and steep downhill sections is mined,and the impact of other significant explanatory variables in the optimal model on operation safety of long and steep downhill sections is analyzed.(3)Research on operation safety of highway curve section based on reliability analysis of uncertain parameters.Firstly,aiming at the possible failure modes that can cause crashes of vehicles(small-sized vehicles and heavy trucks)on the curve sections,the multi-mode failure systems of small-sized vehicles and heavy trucks in series in the curve section are established respectively.To try to explore the new relationship between failure modes,multi-mode failure systems with a parallel mode are also established.Secondly,the single-mode failure and multimode failure of 1097 curve sections are analyzed,and the relationship between single-mode failure probability and multi-mode failure probability and highway traffic crashes is established to examine and compare the single-mode failure and failure systems.Then,to explain the heterogeneity caused by factors not observed in the crash data,the negative binomial model random effects/random parameters/correlated random parameters negative binomial models of single-vehicle crashes of small-sized vehicles considering multi-mode failure probability are developed,and the random effects/random parameters/ correlated random parameters Poisson models of heavy truck crashes considering multi-mode failure probability are also developed.Finally,based on the optimal model in the above crash prediction models,the relationship between multi-mode failure probability and operation safety of curve sections is mined,and the impact of other significant explanatory variables in the optimal model on operation safety of curve sections is analyzed.(4)Verification,comparison,and application of highway safety indicators from two perspectives of reliability analysis.The reliability analysis of the two perspectives is verified and compared for two typical sections: long and steep downgrades and curves.By developing crash prediction models that only consider highway-related factors,and developing crash prediction models that consider highway safety characterization indicators from two perspectives respectively(Highway design parameters with less impact on traffic crashes are replaced by highway safety characterization indicators),the highway safety characterization indicators from two perspectives are examined,and compared through the comparison of crash prediction models.The results show that the highway safety indicators from both perspectives can be used for highway operation safety analysis,and the highway safety indicators from the perspective of uncertain parameters are better than those from the perspective of determining parameters.Finally,the highway safety indicators from two perspectives are applied in the highway safety reconstruction.This study provides a new idea for the highway operation safety analysis,enriches the theoretical system of highway operation safety analysis,and helps to improve the level of highway design,management and operation safety.