Research On Freeway Network Rational Scale Under The Comprehensive Transportation Environment

The highway has the speed, large capacity, high security and other technical and economic characteristics, which greatly promoted the social and economic development and has been paid more and more attention by all countries in the world. Since the end of 1980s, the construction of the highway was beginning in China. To the end of 2015, the mileage of China’s highway is up to 123,000 kilometers, ranking first in the world. The gradually highway network directly stimulated the rapid growth of the number of motor vehicles, a series of problems about the car oriented regional urban development patterns are increasingly prominent. Such as highway congestion, multiple accidents, excessive energy consumption and serious environmental pollution, etc.These problems are due to the comprehensive transportation structure in our country is unreasonable, excessive dependence on road transport, especially for highway.China’s comprehensive transportation system has entered the "transfer mode, adjust structure" stage, with high-speed rail, inland waterway, represented by green intensive modes of transportation continue to grow, at the same time as the representative of the extensive highway transport appeared inflection point. The traditional method of forecasting reasonable scale highway do not consider the combined transport effects, is no longer applicable.Based on the above background, this paper under the stick to the concept of sustainable comprehensive transportation integration development, targeted with reasonable scale of research of regional highway network, combination of qualitative and quantitative research, to support the development of the regional highway network decision-making, goals, layout scheme is of great practical significance.First, studied the highway development and the evolution process and pattern and network prediction model at home and abroad, know the development of domestic and international highway evolution, and realized the traditional prediction methods often independent of comprehensive traffic, which is considering the influence factors is comprehensive, and inaccurate prediction results was inaccurate.Secondly, studied the comprehensive transportation system and the reasonable road network scale theory, discusses the comprehensive traffic development stage, traffic integration and function orientation of the highway, meaning and influence factors of reasonable size etc. Through comprehensive comparison and analysis with the developed countries, has been found that the development of comprehensive transportation system in our country is in the primary stage, and the structure is not reasonable, the highway has been significantly ahead of the social and economic development.Then, using the ideas of total amount control system structure optimization, first determine the region comprehensive transportation network reasonable scale, and through structural and multi-objective optimization model, set different objective functions for optimization, to determine the rational scale of regional highway network. Considering the complexity of the comprehensive transportation system, for convenient calculation, to idealized treatment of comprehensive traffic, assuming that only the highway and railway in two ways.Finally, taking Shandong Province as a case study. The condition of regional development in Shandong Province, the current situation of the development of comprehensive transportation network in Shandong province and the objective planning are analyzed. Based on the consideration of the comprehensive transportation system, it is considered that the planning of the expressway network is not reasonable. Based on the modified connectivity degree method and analogy analysis method combining forecast a reasonable scale of integrated transport network in Shandong Province and through structural and multi-objective optimization model set highway leading, railway guide, integration of three different development model were calculated the scale of highway while combination the actual development of Shandong Province. This paper also puts forward some suggestions for the development of Shandong highway network planning and layout.Under the situation of the provincial highway construction enthusiasm rising, this paper according to consideration of the comprehensive transportation, researching the rational scale of regional highway network, the conclusions of the study for the construction of the highway blindly planning has important practical significance and also helpful to the scientific and rational development of Expressway in our country, which can go on the road of sustainable development.