The Golden Gate and George Washington bridges, are two iconic American examples of suspension bridges, but the longest in the world is Japan’s Akashi Kaikyo Bridge, which covers 6,432 feet. One of the oldest forms of engineering in the world, the suspension bridge is not suitable for all situations.
The area covered by a suspension bridge is very long in proportion to the amount of material needed to build the bridges.
Built on waterways, suspension bridges can be built high, allowing large vessels to pass unhindered by the bridge. The Golden Gate Bridge has a clearance of 220 feet above the waters of San Francisco Bay at high tide.
During construction, temporary central supports need not be built, and access to the building is not needed from below. This means busy roads and waterways should not be disturbed.
The suspension bridges are flexible, which is an advantage as long as the conditions become serious. Instability in extremely turbulent conditions or during strong earthquakes may require temporary closure. In 1940, strong winds caused the Tacoma Narrows Bridge, near Seattle, Washington, from collapse.
Once built in soft ground, suspension bridges require extensive and expensive foundation work to combat the effects of heavy load on foundation towers.
Flexibility also becomes a disadvantage when high concentrated loads are involved. Suspended bridges are not typically used for regional rail crossings that carry maximum weight loads, which adds a dangerous stress to the structure.