Graduation Design of Civil Engineering Road and Bridge

1.1 Background: Due to the needs of social production and consumption, people must overcome the barriers in space to achieve the movement of people and things. The economic activities to provide services for the specific realization of this movement become transportation. Transportation has an inseparable relationship with the national economy. It is the lifeblood of the national economy, the link between industry and agriculture, cities and villages, production and consumption, and the "first palace" of the national economy. Highway is one of the modes of transportation. Compared with other modes, it plays an important role in the whole transportation system. Its characteristics are: (1) It is flexible and can adapt to various terrain conditions, and can quickly concentrate and disperse goods at the specified time and place. (2) The "door to door" transportation is directly loaded and unloaded at the three points of cargo collection, and no transit is required. So as to save time and cost and reduce cargo damage, especially short distance transportation. (3) With good accessibility, it can go deep into remote areas or mountainous areas, and directly connect with any industrial and mining enterprise factory or residential area. (4) Less investment, high social benefits, less investment in road transport compared with railway and air transport, and quick results. The construction of highways has brought remarkable social and economic benefits to the vast areas along the line. (5) The transportation cost is on the high side. Because of the high price of automobile fuel, the number of service personnel and the small unit volume, the highway transportation cost is generally higher than that of railway and water transportation.