[kazen44]

> When people walk across a bridge and it starts to sway, they start to lock step and then resonance, where each step reinforces the last kicks in and more and more energy causes sway, shear and what have you forces. It gets worse and worse and then failure. Tacoma Narrows is another classic example of resonance but due to wind - that informed designs that don't fly!

this anecdote reminds me of the story of ancient rome. (I don't know if this is actual history or a myth).

Apparently, when roman military engineers build a bridge, they where forced to stand beneath it while the rest of the cohort marched across the bridge to test it's strength.

Marching gives exactly this same resonance effect.

[tjalfi]

Your anecdote reminds me of this quote about Dupont's safety program.

"My company has had a safety program for 150 years. The program was instituted as a result of a French law requiring an explosives manufacturer to live on the premises with his family." - Crawford Greenewalt

[nuclearnice1]

Apparently the British army were told to break step when crossing bridges to avoid that potential disaster.

https://en.m.wikipedia.org/wiki/Broughton_Suspension_Bridge

[lou1306]

I think it's common military training in a lot of places. I'm italian, my dad did his service in the Engineering corps (Genio) and he told me the same story. No lock step while crossing bridges.

[randomswede]

Never had it in re bridges, but "no lock-step while carrying a stretcher" was a mandatory part for me.

[todd8]

My father was an officer in the Marine Corp during WW2 and he told me (many years ago) about being taught this in his training.

[gerdesj]

It's true. My dad was a Colonel, my mum a Captain and I was a cadet! Grandad was a Major etc etc