Study On The Ramp Capacity Of Highway Interchange

Interchange is the important part of the highway network system, which is the ties ofvehicular traffic conversion among the intersect roads by spatial separation; however theinterchange ramp is the material basis. With the rapid development of China’s economicconstruction and substantial increase of car ownership, the problem of traffic congestion andthe size of a freeway interchange are increasingly prominent and become the focus ofwidespread concern. The size of the different types interchange ramp capacity is a keyindicator of the reasonable scale control of interchange design and vehicles run smoothly,which is also the basis for the interchange design theory continue to develop and mature.In this paper, it is the object of direct exports, parallel one-way single lane entrance ramp,through the analysis of the regional division of Interchange, lane divided, ramp capacitydefinition and the different types of ramp divided. Through the analysis of the operatingcharacteristics of the vehicle traffic in the freeway interchange triage area, merge area andramp sections area, the ramp capacity calculation model of triage area is built based on thelinear relationship model between speed and density by Greenshields and traffic flowrelationship among the three parameters; the ramp capacity calculation model of merge area isbuilt based on gap acceptance theory under the analysis of the traffic model of main lineoutside lane and the headway distribution by the probability calculation method; the rampcapacity calculation model of ramp section area is built based on the following theory by themeans of the mathematical geometric。According to the definition of the level of service andinfluence factors analysis, the existence problem in the service level grading is pointed out.Combined with the operating characteristics of the vehicle on the ramp, vehicle speed andtraffic density as a ramp service level evaluation is proposed from the perspective of stabilityanalysis of traffic.Furthermore, the triage area ramp capacity recommended value of the proportion of largeand medium-sized cars is proposed based on the different design speeds of different typesramp combined with the location characteristics of the vehicle operation “bottleneck” oftriage area; the merge area ramp capacity reference range of the proportion of large andmedium-sized cars is raised depending on the mainline road grade, the number of lanes,design annual average daily traffic; ramp sections area ramp capacity reference range of theproportion of large and medium-sized cars is given based on the different types of rampdesign speed corresponding geometrics technical indicators. Finally, according to thecaculation method of the ramp service level evaluation index, the service level gradingstandard of different ramp is proposed.