Structural collapse attorneys respond with a qualified yes. Since ancient times, armies have long broken step when walking across bridges due to the danger that the structure might collapse under them if they continue to march in step. Not all bridges or structures are susceptible to collapse from rhythmic human activities.

But where design flaws or structural weaknesses exist, and human rhythmic activity matches the resonant frequency of the structure, the effect over time will weaken the structure and cause its collapse. But it does not require coordinated human effort to break down a structure where the right conditions exist.

Our structural collapse attorneys point out that the Tacoma Narrows Bridge in the U.S. Pacific Northwest stands as the classic example and lesson on bridge collapse. The wind matched the resonant frequency in the bridge and caused it oscillate and finally collapse in a spectacular accident that still captures the imagination today. Aero-elastic flutter resulting from high winds, along with solid sides that let the wind pass through the bridge’s deck, caused the bridge to sway and oscillate vertically and finally collapse. Workers noticed the dramatic sway and flutter during the bridge’s construction phase. The bridge finally collapsed in November 1940 only months after it opened.

Our structural collapse attorneys further note that the classic modern example of bridge collapse brought about by an army’s march is the failure of the Angers (or Basse-Chaine) Bridge in France in 1850. A battalion of more than 400 French soldiers was marching over the suspension bridge when it fell. More than 200 of them perished in the bridge collapse. A storm at the time had caused the bridge to oscillate in the wind. It is thought that the soldiers’ attempts to balance themselves against the wind and swaying of the structure inadvertently led them to match themselves to the natural resonant frequency of the structure. This effect enhanced the effects of the wind to create a sufficient force to weaken and snap the bridge’s anchoring suspension.

Our structural collapse attorneys caution that you can’t always know in advance whether a structure is susceptible to destructive forces caused by matched and enhanced resonant frequency oscillation. Matching rhythm in a march or a dance magnifies the dynamic “live” load that a structure must bear. So take care, and break step in your marches or dances when crossing bridges or enjoying the amenities of poorly constructed buildings.