Research On Reasonable Spacing Between Successive Exit Terminals Of Interchange Ramps In Mountain City

The reasonable spacing between successive exit terminals in interchange rampshas an important effect on safety level, traffic efficiency in ramp,based on trafficoperation conditionin ramp successive exit area in mountainous city, the reasonablespacinghas been discussed and studied, so as to provide technical reference forinterchange planning and designing in mountain city.This paper first definesthe reasonable spacing of ramp successive exit terminals,based on investigationexit ramps in Chongqing,the combined mode of exit rampsisclassified. The influencing factorsof spacing between successive exit terminalsisanalyzed from the aspects of geometric design conditions, traffic conditions, drivingbehavior, traffic signs set and so on.Secondly, after traffic observation of ramp successive exit area of4interchangesin Chongqing, traffic volume, speed, traffic density three-parameter relationships andheadway distribution, lane change behavior, split point distribution, gap acceptancewere analyzed.The effect of spacing between successive exit terminals in interchangerampson safetyhave been made in different traffic conditions and road conditions bythe traffic simulation test.The reasonable spacingbetween successive exit terminals in a rampis composedofidentifysight distance at exit,reaction distance of traffic signs, vehicles changinglanes required minimum safe distance, deceleration lane length. Based on traffic signcognitive theory, driving behavior theory and gap acceptance theory, velocity variationcharacteristics in deceleration lane, respectively, the reaction distance, minimum safetydistance required by lane-change, the length of the deceleration lane have beenresearched. The reasonable spacing calculation model between successive exitterminals in a ramp has been established, and then, therecommended standards ofreasonable spacing between successive exit terminals in a ramp have been put forward.In addtion,the reliability of the reasonable spacing calculation model is verified by aproject example.Finally, the reasonable spacing calculation model which is evaluated by theservice levels and traffic efficiency,is checked by VISSIM traffic simulation software,it proved that the model can be used to plan and design for interchange in mountaincity.