Three Rings Highway (1984-1987) | Planning Stage | Study of Road Network
Type of urban road network
Urban Road System is essential to meet the need of urban development, urban land use and transport. The form of road system is depended on city’s social, environmental, infrastructural and economic conditions. The common form of road network can be classified as following types:
Grid Network is a typical type of road network which is suitable for flat land city. It is a plan in which streets run at right angles to each other, forming a grid. It is beneficial for the configuration of buildings, multiple parallel roads could diverse traffic. However,it is not convenient for diagonal traffic. To solve the problem, some cities added several diagonal roads based on the grid road network. But it created triangular plots which is not advantageous for building configuration and it results in complex urban network. The grid network system can also follow the nature of landscape not necessary need to be perfect grid.
(2)Ring Road System
Ring and radial road system is originated in Europe which is a common type for big city organized by plaza. This type of road system is beneficial for connecting the central of city, suburb and countryside. The network could easily bring outer traffic to central in a short period of time, leading to excessive centralization of traffic. This type of network system is not as flexible as grid system as it contained many irregular urban blocks. Ring road system promotes a orbital urban development, meaning the city expands radially.
To avoid the disadvantages of ring road system, some foreign city, for example, Hannover, reconstructed the network system to several expressways to ease congestion problems in city center, promoting city to develop outward along the expressway.
(3) Free Network System
Free network system is suitable for a undulating terrain. The network system is irregular following the natural landscape.
There is many variation for this kind of network system. A good economic benefit and pedestrian-and-vehicle dividing system can be achieved if take careful consideration of the land use, building configuration, road construction and greenery. Free Network system can form a lively and rich cityscape. One of the example is Maumelle in the USA. The city is located at a hill, integrating the lake, grassland, urban land and industrial area along the highway.
(4)Combined Road System
Combined road system is a road network system combining the advantages of different type of network system. A common type of combined road system is integrating grid system and ring road system. Beijing is one of the examples.
Tianjin’s road network is the second type of system, ring road System. This is largely due to the geographical condition, especially the river. Historically, Tianjin developed radially from Sancha Estuary, following the meandering river like a web. The web is organized and develop into three rings, outer ring, middle ring and inner ring, interconnecting 14 main roads, forming a road system called “三環十四射”(Three rings and fourteen arterial roads). It also become a main feature of Tianjin’s cityscape.
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文国玮. 城市交通与道路系统规划. 清华大学, 2007. 102-103