The Study Of Delay Of Roundabouts Locate On Undulate Roads In Hilly City

The roundabout locates on an undulate road in a hilly city is limited by terrain, because thelocation of the roundabout is at the junction of two roads which in different elevations. Makingone the entrances of the roundabout always has a slope. The capacity of the roundabout locateson an undulate road in a hilly city is limited by the smaller radius of the center island and thelower circulating speed. If the capacity cannot meet the traffic demand, it is not easy to covert theroundabout locates on an undulate road in a hilly city to signal control intersection because thestadia is limited.so it is indispensable to study the delay of the roundabout.Delay is one of the important parameters to evaluate the efficiency of intersection operation.The factors affect delay of roundabouts including capacity, conflict flow rate, critical gap andfollow-up time. Because of the particularity of roundabouts locate on undulate roads of hilly city,making delay and capacity model set up by predecessors cannot be applied directly. Therefore,making clear the interaction of the slope and related factors, establishing the corresponding delaymodel is imperative.This article analyzed the characteristics of the roundabouts located on undulate roads in hillycity. Through analyzing the delay and follow-up time data, finding that the existence of the slopewill increase the value of follow-up time and the effect on follow-up time of uphill behavior ismore apparent than downhill behavior. Establishing the follow-time model about the gradient ofslope based on follow model. At the same time, testing the distribution of headway of Yuanjiangroad roundabout by negative exponential distribution and Cowan M3distribution, finding thatfitting result of negative exponential distribution is more accurate. Meanwhile, checking theheadway of arrival vehicles by poisson distribution test, the results show that the arrival ofvehicle obey the poisson distribution. On the basis of the former study, setting up capacity anddelay model by using the gap acceptance theory and queuing theory, and verifying the model bythe real data. Validation results show that the model can forecast the delay influenced by slopereasonably.