In simple terms
A suspension bridge hangs its roadway, called the deck, from cables strung between two or more tall towers. [1] Thinner vertical cables, called suspenders, connect the deck to a pair of main cables that sweep down from each tower and are anchored firmly into the ground or bedrock at both ends of the bridge.
How it works
The main cables carry the bridge’s load almost entirely in tension, meaning they are being pulled taut rather than pushed or bent. [1] That tension is transferred down through the towers into the ground, and out along the cables into the anchorages at each end, which must be heavy and firmly founded enough to resist the enormous pulling force of the loaded cables. The deck itself is relatively light, since it only needs to carry traffic, not to span the distance structurally on its own.
Why it matters
Because the main cables can be made very long and strong relative to their weight, suspension bridges can cross far greater distances without any support in the middle of the span than beam, truss, or arch bridges typically can. [1] That makes them the practical choice for crossing wide shipping channels, deep gorges, and other sites where building piers in the middle is difficult, expensive, or would block traffic below.
Where you’ll see it
- Major harbor and strait crossings, where ships need clearance beneath the span
- The Golden Gate Bridge in San Francisco and the Brooklyn Bridge in New York [2]
- Mountain crossings over deep river gorges
- Toll bridges connecting islands to the mainland
Example
The Golden Gate Bridge spans more than a mile of open water between its two towers, a distance that would be impractical for a bridge resting on a row of closely spaced piers. [2]
Often confused with
A cable-stayed bridge also uses cables and towers, but its cables run in a fan or harp pattern directly from the tower to the deck, without the long sweeping main cables and separate suspenders that define a true suspension bridge, and it typically spans shorter distances.
Key facts
- In a suspension bridge, the roadway, called the deck, hangs from vertical suspender cables connected to two large main cables draped between towers.1
- The main cables carry the load in tension and are anchored into massive blocks or bedrock at each end of the bridge.1
- Suspension bridges can span much longer distances without intermediate supports than most other bridge types, which is why they are used across wide waterways and deep gorges.1
- The Golden Gate Bridge and the Brooklyn Bridge are well-known examples of suspension bridges in the United States.2
Quick checkWhy are suspension bridges used for very long spans where other bridge designs are not?Show answer
Because their main cables carry the load in tension, which lets the bridge stretch across a long distance without needing supporting piers in the middle.
Sources
- Encyclopaedia Britannica. Suspension bridge. Undated (accessed 1 November 2026)
- Federal Highway Administration. Bridge History and Types. Undated (accessed 1 November 2026)
Editorially reviewed by Last reviewed November 1, 2026Researched and drafted with AI assistanceReport an issue