Quebec City, QC Bridge Collapse, Sept 1916

Quebec Bridge Collapse 1916

After a Royal Commission of Inquiry into the collapse [of the Quebec Bridge in August 1907], construction started on a second bridge. Three engineers were appointed: H. E. Vautelet, a former engineer for the Canadian Pacific Railways, Maurice FitzMaurice from Britain, who worked on the construction of the Forth Bridge, and Ralph Modjeski from Chicago. Vautelet was President and Chief Engineer. The new design was again for a bridge with a single long cantilever span, but a much more massive one.

On September 11, 1916, when the central span was being raised into position, it fell into the river, killing 13 workers. The chief engineer was made aware of the problem six weeks before the collapse by the engineer that was responsible for the construction of the centre section, Frants Lichtenberg. Frants Lichtenberg was also working as an inspector for the federal government of Canada at the time.  

Immediately, fears of German sabotage were reported; however, it was soon clear that another tragic construction accident had befallen the structure (a problem with the hoisting devices). Re-construction began almost immediately after the accident and special permission granted for the bridge builders to acquire the steel that was in high demand because of the War effort. The fallen central span still lies at the bottom of the river.

After the bridge's completion in 1917, special passes were required for those wanting to cross the structure. Armed soldiers, and later Dominion Police, guarded the structure and checked passes until the end of the War.

https://en.wikipedia.org/wiki/Quebec_Bridge