All suspension bridges are prone to vibration and swaying due to moving traffic and wind.
These vibration are not a problem as long as they are not in resonance with the bridges natural frequency.
A sign on Albert Bridge, London, asks soldiers to break step when marching over.
This bridge is also prone to vibration when large numbers of people walk over it.
A powerful thunderstorm was raging and the wind was making the bridge oscillate.
As the soldiers attempted to cross, their bodies acted like sails, catching even more wind.
Survivors reported feeling disoriented, as they struggled to maintain their balance and prevent themselves from falling.
A second later, the adjacent downstream cable broke and the deck collapsed throwing soldiers into the river.
A total of 226 people died.
Angers Bridge prior to collapse in 1850.
The disaster led France to lose hope in suspension bridges, and their construction was suspended for twenty years.
As crowds packed the bridge, their footfalls made the bridge vibrate slightly.
Many pedestrians fell spontaneously in step with the vibrations, increasing them.
