How are Bridges Built?

Most bridges rest on supports called piers. A well is built in the river to keep out water, and the piers are fixed in the bed of the river.

The bridge is then built on the piers. The suspension bridges are built by fixing cables across a river from high towers on each side.

The road is hung from the main cables. Cantilever bridges are made in two sections, each supported on a pier near each end of the bridge. The sections meet in the middle of the bridge, giving a long span to it.

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How Many Type of Keys on a Keyboard?

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