A Method for Setting Confluence Marking on Acceleration Lane Based on TTC Conflict Risk
In order to enhance the safety of merging areas,the impact of different forms of traffic facilities on merging vehicles is analyzed,and the methods for setting up safe merging facilities considering speed variation on acceleration lanes are investigated.Firstly,using speed variation as a safety evaluation indicator and based on the vehicle's acceleration and lane-changing processes,the motion process of vehicles behind the merging nose is analyzed.Secondly,Considering the actual lane-changing position requirements of drivers,a model for calculating the length of the prohibited crossing marking(forbidding crossing the same-direction carriageway boundary line)in the merging area is constructed.Then,the maximum requirements are determined by using repeated simulations.A two-way four-lane model is used for simulation,and a comparative analysis of the length of prohibited crossing marking on the mainline and ramp under different flow rates and speeds is conducted.The evolution pattern of the prohibited crossing marking length is summarized.Finally,VISSIM simulation model is built based on the measured data,and the setting effect is verified with traffic conflicts as the evaluation indicators.The necessity of setting the prohibited crossing marking with different flow rates,mainline speeds and ramp speeds is analyzed.The result shows that(1)as the mainline traffic volume increases,the required length of the prohibited crossing marking also increases;(2)the greater the speed difference between the mainline and the ramp,the longer the prohibited crossing marking;(3)as the mainline speed increases,the prohibited crossing marking length also increases,while it decreases with increasing ramp speed;(4)when the mainline traffic volume is in the upper half of level 1 and level 2,rear-end and lane-changing conflicts significantly decrease,while the setting is suggested,after the lower half of level 2,lane-changing conflicts decrease,but rear-end conflicts significantly increase,the control measures should be implemented considering factors such as the proportion of vehicle types in the outermost lane;(5)under service level 3,painting the prohibited crossing marking leads to a significant increase in rear-end conflicts with no significant change in lane-changing conflicts,indicating that setting is not recommended.The prohibited crossing marking can further increase the space for vehicle acceleration,improve merging speeds,and enhance the safety of merging.
traffic saftyprohibited crossing markingmicroscopic simulationtraffic conflictmerging area
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