An Applied Study On Mainline Continuity In Expressway System Interchange

In recent years,with the rapid social and economic development,the traffic volume of many expressways has reached saturation,the service level has declined,technical criteria and expressway network density cannot satisfy the increasing regional traffic need.Under these circumstances,the current expressway network is under the large-scale reconstruction and expansion.Along with this,a large number of expressway system Interchanges come into existence or face reconstruction.Because of the connection and modification of new expressway network,there might be multiple main lines at the intersection of expressways,especially with the introduction of turning at a quadrant posing higher requirement for selecting the optimum proposal of system Interchange.Currently,with decussating design prevalent in expressway system Interchange;there is too much stereotypical thinking in the design.Actually,the overall thinking is still restricted by the pure decussating main lines and ignores the new functions of expressways with the expressway network adjustment.When the main line makes a turn at the quadrant,the pure decussating design for the expressway system Interchange is no longer suitable for traffic volume and functions of road network.Due to the improper use of mainlines in the system Interchange,traffic congestion occurs.During the reconstruction,the concept of continuation in mainlines should be applied to system Interchange in order to adapt to changes in function and traffic needs.The design concept of continuity in the mainline of expressway system Interchange gives priority to functions.The domestic applied research on this design concept is relatively uncommon.Designers tend to place emphasis on traffic volume and ignore the continuity in the function of mainlines.It is worth discussing and further exploring design plan selection based on the continuity in mainlines.Therefore,it is of great necessity to conduct research on the design concept of continuity in mainlines in choosing the best proposal on expressway system InterchangeBased on the domestic and international literature and the context of system Interchange projects in Shandong provincial expressway reconstruction and expansion,this thesis conducts research on expressway system Interchange based on the concept of continuity in mainlines.Considering the current research on interchange with the pattern of turn in a pure quadrant,this thesis proposes the pattern of combining proceeding straight and making a turn in a quadrant in designing system Interchange.This thesis also explores the classification,feasibility and index selection in this area,attempts to break through the convention in design,enriches ideas in designing system Interchange and expects to design more pragmatic and more adaptable interchange.This study is realistically significant in that it offers references in expressway hub interchange design and in the application of mainline continuity concept in designing practice.