A structure constructed over an obstacle to provide safe passage is known as a bridge.
A passage for the movement of traffic is known as a rad bridge. If the level of the bridge is much higher than the level of the road, then it is over a bridge. Similarly, if the level of the bridge is below the ground level it is called the subway.
Characteristics Of Bridge
- Line of the bridge should not have a serious deviation from the line of the road.
- Bridge should be properly levelled.
- Width of a bridge should be sufficient for the traffic.
- Foundation should be kept on strong ground and at sufficient depth
- It should be as economical as possible in terms of construction and maintenance
- It should provide the passage for services like water pipes telephone wires etc.
Selection of the bridge site
In field we take account of different things, while selecting the bridge site. One basic thing we consider is “SESE’ where S= small, E= economical, S= safe and E= earlier.
- A straight section of bridge should be choosen
- Steady river flow without any serious whirls and cross current
- The channel should be as narrow as possible with firm banks
- Suitable high river banks on each side above the high flood level
- Absence of expensive river training works
- Absence of expensive under water construction works
- Long detours should be avoided
- The bridge axis should be free from geological folds and faults
Classification Of Bridge
According to the span (NRS 2045)
- Culvert (length up to 6m)
- Minor bridge (span less than 20 m but total length may be up to 20 m)
- Medium bridge (span less than 20 m but total length more than 20 m)
- Major bridge (span and whole length of bridge more than 20m)
According to the structures
- RCC bridge
- Cantilever bridge
- Arch bridge
- Truss bridge
- Stayed cable bridge
- Beam bridge
- Suspension bridge
- Movable bridge
According to materials used
- Timber bridge
- RCC bridge
- Masonry bridge
- Steel bridge
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