Study On Minimum Spacing Of Interchange Backup Exit Ramp Based On NGSIM Dataset

The high traffic accidents in the highway exit area have always been a weak point in China's highway safety.After analyzing the accidents in the export area,it was found that the driver's missed exit and improper emergency measures were one of the main causes of frequent accidents on the exit area.When the driver arrived the exit,due to negligence,unfamiliarity with the road conditions,failure to read or understand the traffic signs,etc.,it was not clear that he had to,he was still driving at a high speed in the normal driving condition without turning to leave the main line.After the driver realizes,he has missed the best position of the steering.Due to the urgency of entering the exit ramp,the driver instinctively adopting emergency steering or emergency braking transfers to the exit ramp.For vehicles that have already passed the small gore nose of the exit,they have to reverse or turn back and go back to the exit ramp.On the highway,dangerous emergency measures are taken,which can easily lead to the avoidance of vehicles at high speeds in the rear,causing serious traffic rear-end accidents,resulting in high accidents in the exit area.This paper is mainly based on the frequent events that missed the export of the interchange,and according to the forgiving highway concept,proposing that every driver who missed the exit should not be required to respond promptly,accurately and safely in the face of such an emergency.The forgive design of the highway should be designed to meet the objective needs of the driver.After analyzing the existing forgive facilities of the highway,all of them can not meet the needing of missing exit vehicles safety and quickly return to the original correct direction.It proposes a new forgive design for the missed interchange exit event-the interchange backup exit ramp.At the same time,the paper proposes to increase the minimum distance problem of the interchange backup exit ramp,and divides the minimum distance into three segments: the distance traveled by waiting for the outer lane safety clearance,the travel distance required to change the lane,and the length of the interchange backup exit ramp.Based on the modified second-order Erlang distribution,the paper establishes a calculation model for waiting for the safety gap of the outer lane.Based on the NGSIM dataset,BP neural network is used to determine the length of the vehicle required to complete the lane change at different design speeds.The length of the interchange backup exit ramp is determined based on the “Guidelines for Design of Highway Grade-separated Intersections”.Finally,the paper selects the 5th polynomial to predict the lane change trajectory of the vehicle,and selects the lateral force coefficient as the evaluation index and uses Carsim software to verify the safety of the minimum distance of the interchange backup exit ramp,thus determining the needing minimum distance of different design speeds highway increasing the interchange backup exit ramp.The highway sets up the interchange backup exit ramp,in order to reduce traffic accidents in the highway exit area,provide reference for highway designers,and improve the design method for developing interchanges in China.