Which bridge type is best suited for strong winds and dynamic loads, and can be used as a temporary prefabricated pedestrian bridge?

• A. Movable Bridge
• B. Cantilever Bridge
• C. Beam / Girder Bridge
• D. Truss Bridge

Answer: (D)

Strong winds and dynamic loads stress a bridge mainly through lateral forces and vibration, so a structure with high lateral stiffness and multiple load paths handles these effects best. A truss bridge achieves this by using a network of triangular elements that form a rigid frame. The triangles distribute loads efficiently across many members, which reduces deflections and dampens vibrations under gusts and moving loads. The redundancy of many members also means local failures don’t immediately compromise the whole bridge, which is a big advantage for safety under dynamic conditions.

This same triangulated, modular design lends itself nicely to prefabrication. Truss components can be manufactured in a shop, shipped as ready-to-assemble modules or frames, and quickly erected on site with simple connections. That makes it practical as a temporary pedestrian crossing, since it can be installed rapidly, removed when no longer needed, and reassembled elsewhere with minimal on-site work.

Movable bridges are designed to open for ships, which isn’t the goal here; cantilever and beam/girder bridges can be strong and easy to fabricate, but they don’t offer the same combination of stiffness under dynamic loads and ease of rapid, modular temporary assembly as a truss configuration.