Which bridge type is best known for long spans and draping cables, suitable for river crossing and earthquake zones?

• A. Cable-Stayed Bridge
• B. Arch Bridge
• C. Cantilever Bridge
• D. Suspension Bridge

Answer: (D)

The key idea here is that long-span suspension bridges use main cables that drape over tall towers, with the deck hung from vertical suspenders. That draped cable arrangement is what gives suspension bridges their distinctive look and, more importantly, their ability to span great distances. By transferring most of the load to the main cables and anchorages rather than relying on numerous supporting piers in the water, the bridge can cover wide rivers with minimal obstruction to navigation.

This design is especially well suited to river crossings because you can have very long spans and few supports in the water, which reduces piers that could interfere with ships. In seismically active areas, the same flexible system helps absorb and dissipate energy, with the deck able to respond to movements and designers able to incorporate damping and tuned mass or other seismic-resisting features, though it does require careful seismic detailing to avoid wind- and earthquake-induced instabilities.

Cable-stayed bridges, arch bridges, and cantilever bridges each have different load paths and span characteristics. Arch bridges rely on arch action and typically need solid abutments and shorter spans. Cantilever bridges involve projecting arms that meet at the center and aren’t defined by draped cables. Cable-stayed bridges use cables directly from towers to the deck in a fan or harp pattern, without the main draped cable system that characterizes suspension bridges.