Study On Key Technologies In Expressway Reconstruction And Extension Project

It is an ongoing dynamic process for freeway to adapt to economic development, and the evolution trend for their relationship experiences from adjustment to maladjustment to adjustment. With the increasing of traffic volume, reconstruction and extension of freeway has become a hot spot in China's freeway construction. However, the project designed for reconstruction and extension of freeway is different from the new construction,because it lacks relevant design standards and norms. Therefore, it is urgent to carry out research on reconstruction and extension of freeway.This article combines existing reconstruction and extension projects of freeway with modern survey technologies and design methods of freeway to research on the data processing of reconstruction, the evaluation of existing road condition, the technical indicators and scheme selections of reconstruction and extension of freeway, the splicing technology of the reconstruction and extension of freeway, and transportation organization and so on. Research results are mainly manifested as follows:1) Analyse the data requirement in the design of reconstruction and extension projects and put forward a more comprehensive set of the data collection methods of existing road, as well as the geometry linear fitting methods and accuracy control indicators of existing road.2) Taking the Shanghai-Nanjing freeway reconstruction project for example, propose freeway traffic prediction method of the reconstruction and extension based on the transport corridor, research on the evaluation methods of traffic capacity and service level of freeway before and after the reconstruction and extension and establish road condition RCQI evaluation system.3) Based on the conclusion of typical freeway expansion project, propose advices on the rational use of technical indicators, which plays important part in the design of reconstruction and extension of freeway, including the treatment of the dividing and combining flow in the local co-rotating separation schemes, the reasonable changes of the width of the compressed hard shoulder of the local sections (points), the number of basic lanes and the balance of the lanes, and the choices of longitudinal indicators and so on, which can provide technical support for the modification of the industry-standard specifications.4) Study on the reconstrution and expansion modes of the freeway, propose five highway schemes of reconstrution and expansion, which are unilateral splicing, unilateral plane separation, splicing on both sides, separation on both sides and the form of combination, and establish the freeway scheme selection model of the reconstrution and expansion based on the AHP-fuzzy comprehensive evaluation method, which is applied in the Shanghai-Nanjing freeway reconstruction project.5) On the basis of Shanghai-Nanjing freeway reconstruction project, research on the splicing technologies in the freeway projects of reconstrution and expansion, including Subgrade splicing technology, pavement structure technology, and bridge splicing technology, which can provide technical support for the associated road expansional projects.6) Study the principles, methods and procedures of the transportation organization during the reconstruction and extension of the freeway; Propose and evaluate the traffic organization schemes of the network layer, which is applied in the Shanghai-Nanjing freeway expansional project.The conclusion in this paper can provide a basis for decision-making and technical support for the freeway projects of reconstruction and expansion.