Modeland Application Of Vehicle Lane Changes At Freeway Offramp

Traffic jam and accidents happen frequently by the unbridled lane changes of the drivers at freeway ramp and its influence area.Minimum lane-changing distance model and vehicle lane-changing model at freeway off-ramp were established,and then how to obtain the reasonable setting location of the AGS(advance guide sign)at freeway off-ramp and the relationship between off-ramp success rate and off-ramp distance were researched.Influence factors for vehicle lane-changing at freeway off-ramp and kinematics of vehicle lane-changing were analyzed for establishing the minimum lane-changing distance model,after then the model was amended to conform real situation better.According to probability theory and queuing theory,the distributions of vehicle arrival rate on special section and the probability for reasonable lane-changing distance were analyzed.Off-ramp success rate helps for establishing the vehicle lane-changing model at freeway off-ramp and then the relationship of off-ramp success rate to off-ramp distance and to actual road condition parameters were studied,which provided theoretical basis for planning ramp area and guiding drivers' driving behavior.The research conclusion was applied to the improvement of setting reasonable location of the AGS(advance guide sign)at freeway off-ramp,and the AGS security setting distance calculation model is established.New reasonable AGS setting distance of six-lane double carriage and eight-lane double carriage were obtained by actual example calculation.The result shows that the AGS's safety setting distance obtained by calculation can be different in various road situations,the current related codes of our country need to be modified.The result indicates that,under a medium traffic volume,driving-out success rate increases with the increase of available distance for the driving-out vehicle on the most inside one of six-lane double carriage,when the available distance for the driving-out vehicle reaches 1000 m,the driving-out success rate can be 90% and even more,and the growth tendency gradually decreases.In order to pursue a higher driving-out success rate,with the increasing of the traffic volume,the available distance for driving-out vehicles should be added,and the promoting difficulty increases.