| Interchanges can overcome the elevation differences of roads in a limited space,realize the safe conversion of traffic,and improve the capacity of roads effectively.The topography of mountainous cities is ups and downs,special road construction methods are used to build interchanges in order to overcome the height difference and achieve convenient traffic.The interchange is a frequent spot of traffic accidents due to its characteristics of complex configuration,large corner,poor sight and difficult in driving.There are very limited experimental studies on the operation characteristics and driving behavior of interchanges,especially those with complex structure.Therefore,conducting natural driving research on interchanges can provide basic data reference for designers and engineers,and improve the safety level of interchanges fundamentally.Vehicle instruments are used to study the natural-driving test of the clover leaf interchange and the spiral interchange with numerous mountainous cities and complex configurations.The vehicle running data and speed control behavior data are continuously collected to study the longitudinal running characteristics of the car and driving behavior.In the natural driving test,16 healthy drivers are hired to drive on many spiral interchanges and clover leaf interchanges in order to collect a large amount of vehicle operation and driving control behavior data.According to the natural driving data,the change of the car speed curve on the clover leaf and the spiral ramp are analyzed to determine the law of velocity change and summarize the speed change modes of the two ramps;and drive into the middle,exit and exit stages of the raft and spiral raft.The speed change length and the distribution position of the starting point and ending point of speed changes in time of entry and middle and exit are studied of the car driving on the clover leaf and the spiral ramp.By analyzing the accelerator and brake pedal force curves of the car when driving on the clover leaf and the spiral ramp to summarize the law of the pedal force variation and obtain its change characteristics to study the driving speed control behavior;count the peak value and time of the pedal force curve for each test,and obtain the peak value,mean value and fluctuation frequency of peak value,and conduct the cluster analysis of distribution to study the peak value variation characteristics of the pedal force curve.Results show that the single ramp of the clover leaf interchange speed change model is divided into four stages,the average deceleration length on the three ramps in the entry is 90.58 m.In the adjustment accelerating section,the average acceleration length on the A ramp and B ramp is 107.57 m and acceleration length on the C ramp is 169.72 m.In the decelerating section in the exit,average deceleration length on the three ramps is 59.01 m.The rising speed change model and falling peed change model on the spiral ramp are both divided into five stages.When the car is rising,the acceleration length is 342.28 m in the decelerating section in the exit,when the car is falling,the deceleration length is 519.09 m in the decelerating section in the entry.When driving on the clover leaf ramp,the distribution of accelerator pedal force is dense and the brake pedal force is sparse,the overall fluctuation characteristics of accelerator pedal force are high fluctuation frequency and dense peaks.When driving on the spiral ramp,the accelerator pedal force is mainly controlled in the ascending stage,the amplitude of variation of the accelerator pedal force is big and the fluctuation frequency of the accelerator pedal force is low in the entry and exit,on the ramp,the fluctuation frequency is high,the peak is dense,the amplitude of variation is small and the fluctuation is continuous.In the descending stage,both the accelerator and brake pedal are controlled,and the overall fluctuation frequency of the accelerator pedal and brake pedal force is high and the peak is dense. |
PDF Full Text Request