Study On The Technical Indicators And Adaptability Of Freeway Diamond Interchange

Interchange is not only an indispensable part of the road network, but also a large-scale constructionof freeway. Currently, freeway construction has a gradual coverage to small cities and towns, meanwhile,limited to our stringent farmland protection policy, the difficulty of freeway land becomes more and moreprominent in economically developed regions. In the case of shortage of land and little left-turning trafficvolume, compared to other forms of interchange, the diamond interchange has a compact layout, which notonly can save area, reduce costs, and ensure the straight mainline a fast traffic flow. If the reasonable trafficmanagement and the organization measures are adapted, the capacity of vehicles’ passing can be alsohigher.the domestic and foreign researches of the diamond interchange was summarized and reviewed in thethesis. then the geometric characteristics, adaptability and advantages of the common interchanges wereanalyzed, at last, made a classification of the diamond interchange and described its geometric propertiesand advantages and disadvantages. Through analyzing the vehicle characteristics and its appropriate designspeed of each diamond interchange ramp, with the analysis of the technical indicators of ramp, ramp levelplane, vertical sections and cross sections, finally this paper identified the recommended value of Sightdistance. What’s more, it determined the cross angle of the intersecting ramp planes and its appropriatetraffic managing way, by analyzing the types and traffic-flow characters of diamond interchange. After that,this paper also did a research on reasonable canalization, limit-speed measures and sight distance assuranceof ramp cross-plane.Through the analysis of diamond interchange adaptability, combined with the crossing capacitycalculation methods and models, proposed by the existing literature, the capacity of turning left on the exitramp of freeway was calculated, with the Following theory as the basis, taking the impact of mixed trafficflow into account; considering the influence of mixed traffic flow, with the Gap acceptance theory, turn-leftinto the freeway ramp capacity was calculated. At last, the adaptable maximum traffic volume under theclass II service level was obtained on the left turned ramp of diamond interchange I sincerely hope thispaper could provide some reference in the process of interchange planning, design, construction andmanagement.