Study On Optimization Of Expressway Reconstruction And Extension Scheme

The expressway is the inevitable outcome of economy development. It plays animportant role in aspects of improving industrial structure and distribution, rationalizing urbanstructure and size, promoting the development of small and medium cities, and amelioratingthe living standard of the residents and narrowing the differences between urban and ruralareas.With the rapid growth of the national economy, the traffic demand for the expresswaytransportation continues to increase, which results in traffic congestion and low efficientoperation problems. In order to adapt and to meet this rapidly growing demand forexpressway transportation, the following measures may be carried out: to build a lot of newexpressways; to reconstruct and expand the existing expressways. In the view of relativitybetween transportation and economy development, to construct new expressways may satisfythe growing transportation demands to some extent and strengthen regions economydevelopment, but meanwhile more negative effects will be brought about, such asenvironmental deterioration and large occupation of land resources. By comparison, toreconstruct and expand existed expressways has some advantages, such as less landoccupation and little pollution. Therefore, in most cases to reconstruct and expand expresswayis very popular selection for increasing expressway traffic capacity.On the other hand, usually the expressway reconstructing and expanding projects inChina is designed based on widening width of the roads, and often can not from a systematicperspective take the impacts produced by reconstructing and expanding single expresswaysection on the through capacity of the whole expressway network into account. Furthermore,the different reconstructing and expanding schemes have their own pros and cons, sooptimizing the project schemes which can require the minimum investment and give themaximum benefit has become a major task to be immediately solved.The research of this thesis has focused on the following aspects:1. Summarizing the developing history of China’s expressway, analyzing the problemsoccurred in the developing process and the trends in the future, and reviewing the researchstatus both at home and abroad in the field of expressway construction and expansion.2. Introducing and applying the principles and models of the traffic demand forecast bythe traditional four-stage method.3. Presenting a traffic forecasting method and a model for traffic trends volume, inducedtraffic volume and diverted traffic volume on expressway segment, representing principlesand approaches to obtain current OD traffic volumes using anti-OD deducing technique. 4. Studying on several common ways to reconstruct and expand expressway to find theircorresponding superiorities and defections, figuring out an evaluation models of constructioncost per unit mileage in reconstructing and expanding expressway, proposing an optimizingmodels of expressway reconstructing and expanding schemes which takes the lowest cost andthe appropriate through capacity as the goal, and giving specific operation steps needed in thesimulated annealing algorithm to solve the problem.5. Applying the method mentioned above to the case studies in order to obtain theoptimum reconstructing and expanding scheme in accordance with the steps of trafficforecasting, through capacity analyzing, and solving the model. The results show that themodel and method to solve the model are reasonable and practicable.