What are the six horizontal passages of China traffic trunk network?

Transportation is one of the components of national economy and society, and the proportion of land and space it can occupy must be coordinated with the development of other departments, which is limited. At present, the large-scale transportation infrastructure network can't effectively adapt to the current transportation demand. Facing the multiplied transportation demand in the future and the requirements of building a modern metropolis for a developed, smooth and efficient transportation system, land supply and spatial layout will be the biggest challenge in the future. The layout of China transportation corridor is five vertical and five horizontal comprehensive transportation corridors, including Heihe in Heilongjiang to Sanya in Hainan, Beijing to Shanghai, Manzhouli in Inner Mongolia to Hong Kong, Macao and Taiwan, Baotou to Guangzhou, Helin in Inner Mongolia to Fangchenggang in Guangxi Zhuang Autonomous Region, Tianjin to Kashgar, Qingdao to Lhasa, Lianyungang in Jiangsu to Alashankou in Xinjiang Autonomous Region, Shanghai to Chengdu and Shanghai to Ruili in Yunnan. Since the reform and opening up, China's transportation infrastructure network and transportation industry have made great progress, the network layout has been continuously improved, and the overall strength has been significantly enhanced, and urban transportation is no exception. However, with the rapid development of economy and society, the continuous increase of urban population, the large-scale expansion of built-up areas, motorization and the accelerated development of cars entering families, the passenger and cargo flow and traffic volume of activities inside and outside the city have increased sharply, reaching a higher level. Moreover, it shows a trend of sustained and rapid growth, and the contradiction between supply and demand is becoming more and more prominent at the level of high demand scale, and the existing development concepts and models are seriously challenged. Based on the current development situation and the final scale requirements, various modes of transportation need a development process of scale expansion, perfect layout and structural upgrading. Although urban transportation has a relatively developed transportation network in China, it corresponds to the high concentration of urban functions, population and economy and the scale of transportation demand. At present, various modes of transportation, including railways, highways, civil aviation and urban transportation, ...