Highway drainage, generally with open ditch. Especially in mountainous and hilly areas, the ground slope is large, fast water flow, open ditch can give full play to the role of drainage. When the flood exceeds the design capacity and overflow, remove the water also more quickly. Its drainage facilities are side ditch, interceptor ditch, drainage ditch, drop, rapids, inverted rainbow tube and ferry and so on.
Urban road drainage, urban road drainage has a systematic, more complex, can be divided into diversion system and combined flow system (see drainage system). Urban road drainage design storm return period and runoff into the drainage system, according to the drainage engineering requirements and relevant formulas for calculation. China's original old city road drainage basically are combined flow system, in recent years, new construction, expansion of the region has gradually increased the use of diversion system.
Expanded:
The turn-around valves are capable of meeting the turn-around needs of articulated high-capacity buses with a length of not less than 24 meters, and turn-around valves on highways with a length of not less than 30 meters.
These turn-around valves are usually in a closed state, when there is an accident in front of the serious congestion or water under the bridge is too deep to cause the vehicle can not pass and other emergencies, open the turn-around valves can be diverted to stranded vehicles to turn around and leave or evacuate to other roads.
Baidu Encyclopedia - Road Drainage