Study On Influence Of Different Kinds Of Ramp Combination Modes On Urban Expressway Traffic Flow

As a main skeleton of the urban traffic system, the urban expresswayassumes the main task of transportation between cities. However, theincreasing traffic demand, or traffic accidents leads to the trafficcongestion obviously. Ramps, as an important part of the urban expressway,influence the traffic flow of the main lane a large extent. A reasonableramps distance could relief the traffic congestion effectively.Faced with this situation, this thesis classifies the ramp combinationmodes into four kinds, which are named on-off ramps, on-on ramps, off-offramps and off-on ramps. Then, this study determinates the conditions thatwhether two ramps could be considered as a ramp combination mode, andthe reasonable ramps distance of the four kinds of ramp combinationmodes under different mail lane design speed.Next, the micro simulation software, TSIS, is used for modeling, andsimulating. By using the data from the simulation work, the thesis get threeparameters, the coefficient of speed variation, average delay, and lanechange numbers per vehicle per lane, as evaluating indicators.Using the three evaluating indicators, this thesis studies the trafficflow of four kinds of ramp combination modes under different trafficconditions. Through comparative analysis, the study finds out the keyparameter that influences the traffic flow of each ramp combination mode.This conclusion would help the city traffic managers find the reason thatcauses the traffic congestion on expressway more convenient and moreaccurate.Finally, the thesis uses the three evaluating indicators to compare the traffic flow of the four kinds of ramp combination modes. And then, thestudy determines the order of the all kinds of ramp combination modesunder different parameters. This conclusion would provide the theoreticalbasis for ramp design.