Research On Setting Techniques Of Truck Escape Ramp For General National And Provincial Highway

The general national and provincial highway refers to the national highway and the provincial highway to remove freeway part,which accounts for 20% of the total mileage of china's highway.With the rapid development of the general national and provincial highway,the security problem is becoming more and more serious,especially the safety problems of the long and steep road,the vehicle brake failure caused by accidents.Engineering practice has proved that the best way to solve this problem is to set up a truck escape ramp.However,Due to the lack of relevant standards and specifications in the design of the structure and ancillary facilities,even leading to some truck escape ramp after putting into use caused two accidents,so this paper mainly studies the structure parameters and ancillary facilities for the national and provincial trunk escape ramp.This paper takes the ascending-grade arrester bed as the research objecj and conduct field research for the type,finally conclude that the problems of setting.Combined with the research results and literature gives the influencing factors of the truck escape ramp.The speed of uncontrolled vehicle is the basis of studying the structural parameters of the truck escape ramp.,the paper uses the running speed to study.To analysis the influence factors of running speed,proposing A prediction model for running speed of downhill section based on road alignment,finally,the taking average longitudinal slope,the cumulative slope length,the flat curve radius as independent variables,and using the SPSS nonlinear regression method to establish the prediction model.The model is modified by the "Highway Project Safety Evaluation Code"(JTG B05-2015).The running speed of the uncontrolled truck is analyzed to determine the running speed as the initial speed of the controlled speed of the controlled freight vehicle into the safe lane.It is determined that the running speed after braking failure is proportional to the running time and can be calculated according to the predicted running speed and running out of control Time to determine the entrance speed of the controlled truck.When the resistance is balanced with the gravitational force in the direction of the slope,the uncontrolled truck will do the uniform motion,and the lost truck will reach its maximum speed.In this paper,the prediction speed and mechanics principle and theoretical knowledge are combined to analyze the structural parameters setting requests such as the slope of the arrester bed,the length of the arrester bed,the aggregate of the arrester bed,the angle between the truck escape ramp and the main line and the width of the brake bed and so on.Taking into account road conditions and project costs,the sevice road can't be set in the general national and provincial highwa,but should ensure that the safe lane has sufficient line of sight.In order to improve the safety of the runaway vehicle in the truck escape ramp,this paper suggests that the combination of structural parameters and ancillary facilities to improve the success rate of self-help.Finally,the research results are applied to a general Guizhou Province highway,to improve the K33 + 300 truck escape ramp.Practice has shown that: since K33+300 truck escape ramp has optimal design for six months,there have been 56 vehicles into the truck escape ramp to achieve self-help,the effect is better.It is further proved that the research of the paper has certain theoretical and practical significance.