Research On The Evaluation Technology Of The Traffic Safety Of Highway Large Indivisible Load Transportation

China’s highway network planning and construction are mainly based on the standards of conventional vehicles and cargo transportation.However,the size and weight of large indivisible load transportation are mutually restricted by the geometric conditions and structural loads of highways,which brings challenges to the traffic safety of large indivisible load transportation.In addition,due to the lack of technology and methods,the passability of large indivisible load transportation is mostly based on the experience of the staff,which increases the traffic risk of transportation.Based on this,this thesis is based on the examination and approval department to carry out a research on the traffic safety evaluation of highway large indivisible load transportation,aiming to provide technical support,which has scientific guidance value and practical application significance for large indivisible load transportation.First of all,in this thesis,the transportation enterprises,approval management and consulting units involved in large indivisible load transportation were investigated in six provinces.Based on the analysis of the investigation data,large indivisible load transport vehicles are divided into three types: tractors + long wheelbase trailers,tractors + multi-axle and multi-wheel hydraulic trailers and tractors + special combination trailers.Secondly,this thesis conducts theoretical and simulation research on the four contents of space accessibility.By analyzing the types of large-size vehicles,steering principles,turning passages,failure modes,and the impact of highway space obstacles on clearance,the evaluation models and evaluation standards of highway horizontal curve,vertical curve and clear space accessibility were established respectively.In view of the different elements of the intersection,Auto TURN software was used to create 56 types of cross and 30 types of roundabout models,and the vehicle path simulation and result analysis were carried out.The thesis studies the driving safety evaluation from three aspects: traction ability,braking ability and driving stability.Based on the analysis of the climbing force of the vehicle,the influence of altitude on the traction force and the power reserve coefficient are considered,the calculation formula of the maximum climbing degree is improved.The braking distance calculation formula is deduced by analyzing the deceleration changes of large transportation vehicles during the whole braking process.The calculation model of the allowable cross-slope gradient is established by analyzing the factors that affect the lateral stability of the vehicle and establishing the vehicle force equation.Finally,This thesis proposes the recommended road set and the intersection set based on the evaluation of space accessibility,and proposes the recommended traction capacity level,lateral stability level and speed limits based on the evaluation of driving safety,which improves the scientificity and efficiency of the evaluation.This thesis combines three methods of table lookup,calculation and simulation evaluation.By comparing the advantages and disadvantages of the C/S and B/S architectures,this thesis constructs a hybrid system architecture of the traffic safety evaluation system for large indivisible load transportation,and combines the evaluation methods and evaluation standards to carry out the overall design and subsystem design of the system.It laid a technical foundation for the development of the safety evaluation system for large indivisible load transportation.