Study On Fuzzy Reliability Analysis Method Of Highway Alignment

Highway alignment design should take into account the driver’s psychological reaction,guide their sight,and ensure the safety and comfort of the vehicle.In addition,it is essential to ensure the continuity and coordination of the line shape to enhance the aesthetic appeal of the road.To achieve these objectives,highway engineering technical standards have been developed,which include a series of technical indicators for highway alignment design.However,this design process is complex and non-deterministic due to the many influencing factors that vary greatly with time and space,and the intricate relationships between them.The uncertainty in the design process stems from the randomness and fuzziness of the parameters in the road alignment design index,making it a challenging task.Although the road alignment analysis method based on the reliability theory considers the randomness of the influencing factors,it fails to take into account the ambiguity of the influencing factors.This paper examines the uncertainty of highway alignment design through two approaches: the fuzzy reliability calculation method and highway alignment design parameters.The study introduces the structure of fuzzy reliability theory into the reliability calculation of highway alignment design.Using automobile theory and current code,the appropriate road alignment design index is selected and simulation experiments are conducted to propose a new calculation model for the road alignment design index.Driving data of the expressway is collected and fuzzy reliability analysis is conducted on the design indicators.The main work of this paper is outlined below:(1)This paper proposes three new calculation methods for fuzzy reliability of highway alignment,considering the randomness and fuzziness of highway route design parameters.The methods are based on reliability theory and triangular fuzzy numbers,and involve transforming fuzzy variables into random variables.The equivalent density function method,information entropy method and generalized density function are derived.(2)In this study,Matlab software was utilized to develop a vehicle model and conduct experiments on lateral and longitudinal stability.The obtained data included lateral acceleration,slip rate,and time while the vehicle was operating on the road.SPSS was used to fit the lateral acceleration values at different speeds and adhesion coefficients,which helped establish the relationship between speed,adhesion coefficient,and lateral acceleration.Additionally,a minimum radius model for the lateral acceleration circular curve was proposed.By analyzing the slip rate and adhesion coefficient relationship,the curve of slip rate changing with braking time was transformed into the curve of adhesion coefficient changing with braking time to simplify the calculation model of parking sight distance for the ESC system.The new calculation model was used to calculate the value under the corresponding design speed,and the results were compared with the highway route design specification.(3)To investigate the impact of weather on road alignment design,data on vehicle speeds were collected under three weather conditions: sunny,rainy,and foggy.Statistical analysis was conducted on the data,and three methods were utilized to verify its adherence to normal distribution.(4)To address the ambiguity of driving speed,we establish the minimum radius of the circular curve and the reliability function for parking sight distance.We utilize both traditional and fuzzy reliability calculation methods to solve the function function,obtaining the reliability index and failure rate probability.We compare and analyze the results from three perspectives: reliability calculation method,highway alignment calculation model,and weather.