Study Safety Of Road Freight Transportation Of One Belt One Road Countries Based On Vehicle Dynamics

"Belt and Road Initiative"（BRI）proposed by China regarding the concept of"connectivity"and the significance of"sharing the future community"in the new era focuses on the international road freight transport.During the time of highway transportation,once there is a traffic accident,it will truly influence the productivity and effectiveness of merchandise flow.The bond between the vehicle parameters of the heavy semi-trailer and the road parameters of the mountain road is an essential parameter to studied before the constructions of road.The purpose of my research is to develop the safe and accident-free roadways which ultimately will promote the uniform traffic rules and make the unified regulations on load.In order to deeply study the stability of semitrailer in the process of driving on a mountain highway,the software named Truck Sim is used as analyzing tool that establishes the whole vehicle simulation driving system composed of semi-trailer model,road model and driver model.（1）This paper studies the factors such as speed,specific power of a vehicle,load capacity,gradient of longitudinal slope,radius of curve,corner of curve,transverse gradient of curve,position of load center of mass,etc.,which affect the running speed,lateral acceleration,longitudinal acceleration and shift times of driver of a semi-trailer.When driving uphill,the average longitudinal acceleration has a linear negative correlation with the initial speed of uphill.Therefore,speed limit and load limit signs can be set in the typical longitudinal slope section of the mountain highway to remind drivers to pay attention.This research also provides calculating parameters and a control basis for operating speed prediction,load and limit value determination for the road slope gradient and curve radii.（2）The road model is established with the longitudinal gradient of 3%,4%,5%and6%.At the same time,the load of the whole vehicle is changed,and then the uphill simulation is carried out at different initial speeds.When the vehicle load is 30t and the initial speed is 70-80 km/h,the speed difference of the vehicle is small,the semi-trailer train is safer in the uphill driving process.With the increase of the specific power of the semitrailer train,the minimum running speed of the vehicle in the process of climbing increases.The results in the figure show that for every 0.01kw/kg increase of the specific power,the increment of the minimum running speed V_minof the semi-trailer train is close to 10km/h.（3）When the semitrailer train passes the curve at a speed of 70 km/h～90 km/h,the lateral force is enough to ensure the normal driving of the vehicle,the lower the longitudinal gradient,the more obvious the influence of the speed of the vehicle on the lateral curve acceleration is.When the curve radius is not less than 350m,and the curve angle is greater than 7.5°and rises slowly,the vehicle’s lateral acceleration adjustment in the curve is very minimal.The value of lateral acceleration increases slowly with the increasing speed of a vehicle.To make sure that the vehicle can pass the curve at a higher speed without sideslip or even rollover,the method of increasing the cross slope of the curve can be adopted.When the vehicle is travelling at a speed of 80 km/h on the downhill,the distance between load centroid and the front axle D₁should be less than or equal to 7000 mm and the distance between load centroid and ground D₂should be less than or equal to 2300 mm,so that the semitrailer can maintain a stable driving state.It is hoped that countries along the BRI will get a reference for the road safety standards.