For centuries, people have walked across bridges that are just a log that hangs from “cables” of twisted grass.And they look very risky! They are suspension bridges.
Suspension bridges, unlike beam and arch bridges, have roadways that are suspended (hung) from above. Almost all suspension bridges have supporting truss systems. These are located beneath the bridge’s deck (roadway or path). Truss systems are open networks of triangles. They allow wind to pass through. This helps stiffen the deck. It also reduces its tendency to sway and ripple.
Suspension bridges are the most expensive kind to build. They can also span far longer distances than any other kind of bridge.