Study On Some Key Technological Problems Of Arterial Highways' Rapid Reconstruction

The accelerating process of urbanization and the expanding of urban area, which makes the outer portion of the city where arterials were located be included in the planning and construction scope of the city, and arterial highways were gradually included in city hinterland. With population concentration and streetize of the arterial, using attribute of arterial becomes urban road. However, arterial highways cannot be used directly as urban roads and cannot meet the diversified traffic demand in the regions, so they need rapid reconstruction. Aiming at these problems, this paper attempted to explore several key technical problems in the design of arterial highways' rapid reconstruction.Firstly, through analyzing the effect of urbanization on traffic of arterial highways, the function of arterial highways which need rapid reconstruction was new classified. Then the cross-section layout in the design of arterial highways' rapid reconstruction was studied and it was raised that the key point is selecting the reasonable layout form. Based on analyzing the existing problems and influencing factors of arterial highways' transect layout in rapid urbanization areas, advantages and shortcomings and applicable ranges of three common forms of cross-section layout in the design of arterial highways'rapid reconstruction was researched, afterwards the principles of it and highlights of the existing cross-sections' utilization were summarized.Secondly, selection of the alignment design indexes in arterial highways' rapid reconstruction were discussed, and it was proposed that the key point is how to make choices or tradeoff when conflicts exist between the utilization of existing arterial highways and meeting the design specification. After analyzing the selection of design speed, the selection standards of straight length, curve radius, longitudinal grade and grade length in arterial highways' rapid reconstruction were discussed. Eventually, multistage fuzzy comprehensive appraisal based on AHP (Analytic Hierarchy Process) was presented to evaluate entire degree of safety in the design of alignment elements in arterial highways' rapid reconstruction.Thirdly, the layout of entrance and exit in arterial highways' rapid reconstruction were studied, and the key is to control the minimum distance between entrance and exit which was proposed by analyzing the existing problems at the entrance and exit of arterial highways in fast urbanization areas. Then the minimum distance between a pair of entrance and exit of planar main and auxiliary lane, and the minimum distance between neighboring signal intersections of auxiliary road were researched. At last, how to apply AM techniques to optimize the layout of entrance and exit in arterial highways' rapid reconstruction was discussed. Fourthly, the optimization and transformation of road intersections which are the throat of urban traffic was discussed, and the key is the optimization of intersection's connection with urban freeway ramp and channelization design of intersections. So they were studied respectively, and specific measures were presented to optimize intersection's connection with urban freeway ramp, in addition, methods of setting bus lanes in signal intersection entrance lanes and channelizing pedestrians and non-motor vehicles were summarized.Finally, by using the rapid reconstruction project of Cheng Bei Road in Suzhou, the theory studied above was proved and the design of transformation was evaluated.