China ancient city planning attached great importance to the planning of urban road network. The grid road system proposed in Kao Gong Ji is a model of the road system of ancient capitals and local cities in China. Cities in the river network area south of the Yangtze River have developed water transportation, and the streets are generally arranged parallel or perpendicular to the river. The house is built between the street and the river, with the front facing the street and the back facing the river, with convenient land and water transportation. Most blocks are flat and long.
Grid road system is beneficial to the regulation of traffic flow, and there are many routes to choose from from the starting point to the end point. You can change your driving route when there is a traffic jam. Linear roads are convenient for construction, conducive to building layout, and the blocks are relatively clean and tidy. The disadvantages of small grid road network are unclear road division and too many intersections. Grid road network is not suitable for cities with complex terrain.
In areas with relatively flat terrain, grid road networks are usually used, such as Beijing, Luoyang, Zhengzhou, Xi and Shijiazhuang in China. New york in the United States and Milton Keynes, a new city in Britain, are also representative examples of grid networks. With the square as the layout center, the streets form a radial road network. In ancient Greece and Rome, squares were set up in front of temples, city halls and other buildings as the center of public activities and radial roads. Later, European cities inherited this tradition and used axis composition and road guidance to strengthen the expressive force of squares and urban modeling. His representative works include General Layout of Versailles Palace in Paris and Urban Renewal Planning of Paris. This style has a great influence on other countries. 179 1 year, the Planning of Washington compiled by French military engineer P.C. Longfang takes the Capitol and the White House as two central points, forming a radial road network with the color of this traditional form.
The characteristics of radial road system are as follows: several squares are arranged continuously on an axis to emphasize the role of the axis; Use roads to communicate the links between squares. The streets are straight and the focus is on squares. The traffic route between the main squares in the city is the shortest, but the traffic in the focus square is more complicated; The irregular land divided by roads is not conducive to the layout of buildings. Taking the square as the center of the building complex, the square, building, garden and road are designed as a whole to form a complete geometric pattern. It has a strong centripetal effect on composition. The main road radiates outward from the center of the city, and concentric circular roads are built along the periphery of the city (or the wall foundation of the original city wall is demolished to build circular roads), and the two are combined to form a road network. The road network formed in Moscow in history is a relatively complete radiation-ring combined system.
Since 1950s, the fringe areas of big cities have been rapidly urbanized, and the urban area has been continuously expanded. The concentric urban plane structure makes more and more transit vehicles in the central city mixed with the vehicles in the city, and the traffic flow has exceeded the bearing capacity of the original roads, which has aggravated traffic congestion. The improvement measures generally include: reforming the inner ring road around the central area, improving the road grade, and building a three-dimensional intersection. By means of attraction and control, transit vehicles passing through the central city are forced to bypass the outer ring road. Radial trunk line is a corridor connecting downtown and peripheral areas; The loop is mainly responsible for the lateral traffic connection, which distributes the external traffic evenly to the radial roads. Radial-ring road network structure is not suitable for small cities. Hybrid road network is a comprehensive road network structure that combines the above types of road networks or develops in stages according to urban land use conditions. Road networks that generally do not belong to the above types can also be classified as mixed road networks. For example, in some mega-cities, there are mixed road networks of grid and radial ring. The common formation process is that when the original grid road network expands to a certain extent, it also develops along the radial traffic trunk lines, thus forming a road network structure inside the grid and outside the radial ring. This road network structure is more suitable for big cities and megacities. The square grid road in the city can avoid the excessive concentration of traffic in the city center, and the peripheral circular road can ensure the rapid connection between each district and the city center and between districts. Cities such as Chicago and Osaka all belong to this type of road network.
It should be pointed out that the above typical road network types are put forward to compare the characteristics of different forms. The actual urban road network is often a combination of several types, and there may be advantages and disadvantages of the above types. The planning of urban road network must be analyzed and considered in combination with the actual situation, and is not limited to these typical road network forms.