Which bridge has the world’s longest cantilever span, measuring 549 metres?

The Quebec Bridge has the world’s longest cantilever span, measuring 549 metres.

The bridge crosses the Saint Lawrence River west of Quebec City and carries road, rail and pedestrian traffic. Its cantilever design allows the central span to project outward from massive supports, rather than relying on suspension cables to carry the main opening.

The first construction attempt ended catastrophically on August 29, 1907, when the partly built south section collapsed and 75 workers died. A second collapse occurred during reconstruction in 1916, killing 13 more workers. The completed bridge finally opened to rail traffic in 1919.

The 549-metre record refers to the length of the central cantilever span, not the bridge’s total length. The Quebec Bridge remains a major engineering landmark because its failures led to stricter structural design and construction practices.