| The emergence of interchanges has solved the problems of traffic congestion and traffic safety brought by plane intersections.However,because interchanges serve as the connecting section of two roads,the location is still an accident-prone area.Although there have been many studies that proposed improvement measures based on the accident on the ramp,the failure mechanism has not been studied,resulting in the accident not being eliminated from the design stage of the interchange.The research in this paper is realized by means of simulation.First of all,based on a highway project in Sichuan and chongqing,this article collected the accident data of the interchange area from January 2014 to May 2019,and conducted statistical analysis of the accident to determine the accident-prone interchange and the accident vehicle types;then take the car as an example,use Carsim Carry out vehicle modeling,and use Latitude software to reproduce the design of the interchange based on the design file of the interchange,and output and organize the road data of the interchange,import it into Carsim’s road modeling,and control and adjust the vehicle to ramp from the main line Complete the whole process of the next ramp;then study separately according to the types of accidents,and carry out the simulation experiment of the constant speed and variable speed of the small car on the single horn type interchange;finally,the simulation experiment of the "8" shaped interchange using the car and truck.The research results show that: in the simulation experiment,as the speed of the simulated vehicle increases,the steering angle of the steering wheel becomes larger and the speed of the steering wheel becomes faster in the area where the single horn-type interchange accident is more frequent.On the ramp where Peng’an Interchange and Quxian Interchange have a high incidence,when the vehicle speed exceeds 55 km / h,and when the vehicle speed exceeds 50 km / h on the Yingshan West Interchange,the lateral acceleration occurs in the driving discomfort zone.The study found that these three single-horn accidents have a high incidence of interchanges,all of which have a characteristic that the length of the circular curve accounts for the length of the accident area(circular curve and transition curve).The Yingshan West Interchange and Qu County Interchange account for 62%,and Peng’an Interchange accounts for More than 64%,a large proportion of the circular curve may cause traffic accidents.When conducting a variable speed simulation experiment on a single horn type interchange,the speed curve was found to find that the simulation experiment can better simulate a real vehicle experiment.Carrying on the side-slip simulation experiment on the "8" shaped interchange hub,it was found that the faster the speed in the high-accident area,the smaller the adhesion coefficient,and the more likely the side-skid accident occurred at the vehicle.When studying the simulation experiment of truck on the ramp with high incidence of "8" interchange,it was found that the truck tire load transfer rate became smaller as the road adhesion coefficient and the horizontai slope became larger;the truck tire load transfer rate increased with the increase of vehicle speed,load and height of center of mass.Using the method of orthogonal test,the rollover study on the truck found that the major and secondary order affecting the rollover of the vehicle in the selected factors is: road adhesion coefficient,left and right position of the center of mass,vehicle load weight,center of mass height,ramp radius,Vehicle speed,super high,maximum braking pressure,steering wheel wheelbase,drive shaft wheelbase,steering shaft wheelbase,drive wheel wheelbase;the road adhesion coefficient is the significant effect for vehicle rollover on a small radius ramp.According to the above research results,specific improvement measures to reduce the occurrence of accidents are proposed for the single-horn interchange and the "8" interchange. |
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