Bridge structures

A bridge is a spanning structure that creates a passage over an obstacle such as a river, gorge, valley, road, railway and so on.

Bridges are a common feature of the built environment and one of the key elements of civil engineering. The basic principles of bridge design are dependent on the nature of the spanning structure; its shape, materials, means of support, distance spanned, terrain, function, budget, exposure and so on.

The three basic types of bridge structure are:

• Beam bridges.
• Arch bridges.
• Suspension bridges.

Other definitions related to bridges include:

• A green bridge - a crossing that allows the safe passage of wildlife.
• An overbridge - a bridge crossing over a transport corridor.
• An underbridge - a bridge crossing under a transport corridor such as a railway.
• A viaduct - a bridge like structure composed of a series of spans, used to carry roads and railways across valleys and other depressions.
• A half through bridge - a bridge in which the lower chord carries the vehicular or pedestrian traffic.
• A through bridge - a bridge in which the lower chord carries the vehicular or pedestrian traffic and having cross-bracing located above the traffic.’ Ref Iron and Steel bridges: condition appraisal and remedial treatment, published by CIRIA in 2008.
• The span of a bridge is the horizontal distance between its supports.
• The underside of a bridge is described as a 'soffit'.
• The surface of a bridge which allows passage is describes as a 'deck'.

For more information about the different types of bridges and construction methods, see Bridge construction.

For information about some of the most famous bridges, see Bridges of the world.

Other articles on Designing Buildings Wiki about bridges, include:

• 3D printed bridge.
• Assessing bridges.
• Clifton Suspension Bridge.
• Counterweights.
• Garden bridge.
• Genoa bridge collapse.
• Learning from the Genoa bridge collapse.
• London Bridge and its houses, c1209-1761.
• Optimal arch bridge.
• Queensferry Crossing.
• Saving Dick Nunn's bridge.
• The Iron Bridge.
• The Menai Suspension Bridge.
• The Millau Viaduct.

[edit] Related articles on Designing Buildings

• Aqueduct.
• Arches.
• Bascule bridge.
• Bridge chapel.
• Civil engineer.
• Clifton Suspension Bridge.
• Dam construction.
• Five bridges worth visiting during a UK staycation.
• Going the extra mile to extend the lifespan of the Menai Suspension Bridge.
• John Rennie.
• Movable bridge.
• Navigable aqueduct.
• Parleys Canyon Wildlife Bridge.
• Piers.
• Pile foundations.
• Pontoon bridge.
• Road construction.
• Railway engineering.
• Retractable bridge.
• River engineering.
• Submersible bridge.
• Swing bridge.
• Types of structural load.