Research On Setting Conditions And Technical Standard Of Grade Separation

Grade separations can separate and eliminate traffic conflicts at road network, besides they ensure traffic move fast and safely. As the road network becomes more and more intensive, the role grade separations playing becomes more and more obvious. While there are lot’s of problems to be solved in designing grade separations, such as when to set it and how to select standard. Based on theoretical research national and abroad, by researching theory, analyzing statistics combining with practical problems, this paper makes a research on grade separation setting conditions and key technical indicators, including the impact of road function and road network, reasonable traffic volume for setting grade separation, reasonable distance between grade separations, reasonable clearance selected for grade separation, reasonable angle range of grade separation.Based on the requirement of road function and network plan for road grading and access control standard, establish relationship table among road function, road grading, and cross form selection. Preliminarily determine the cross form range at the intersection.Based on gap acceptance theory and platoon theory do a research on calculation method of non- signalized, main road preferential and free intersection capacity. Combining with national survey on traffic characteristic parameters at non-signalized intersection, with no turning demand as premise, calculate non- signalized, intersection capacity. Put forward the volume condition of setting grade separation for minor trunk first class highway and second class highway. With the method of saturation flow rate, referring to Japanese method of interchange traffic planning methods, analyze traffic conditions of setting grade separation among second class highway, third class highway and fourth class highway.Analyzing factors which affect grade separation distance, introduce the concept of node importance combining with the method of clustering analysis, establish reasonable grade separation spacing model. Compared to the United States, Japan standard analyze grade separation clearance requirements, combining practical problems, propose the right way of choosing reasonable grade separation clearance. Based on the demand of economic, construction, safety, put forward reasonable separation angle.