4 ms·

There is a place in the UK where this happens with spooky regularity with people walking. There is a covered walk way between Waterloo and Waterloo East railway

by alan_cx 14y ago

There is a place in the UK where this happens with spooky regularity with people walking. There is a covered walk way between Waterloo and Waterloo East railway stations. The mob of people enter it unsynchronised and by the time they leave, they are usually all synchronised. I assume this happens in many other places too, I just haven't been every where else to see!!!! I always assumed this was because people can hear each other and subliminally fall in to syc, whether this is the same or not, Im already internally debating!!!

lutusp 14y ago
> There is a place in the UK where this happens with spooky regularity with people walking. Sometimes in the military, when crossing a bridge, troops are ordered not to walk in step, because of the stress it places on the bridge. http://en.wikipedia.org/wiki/Angers_Bridge http://en.wikipedia.org/wiki/Angers_Bridge A quote: "As usual in crossing that bridge, the soldiers had been ordered to break step and to space themselves farther apart than normal." More dramatic: http://en.wikipedia.org/wiki/Broughton_Suspension_Bridge http://en.wikipedia.org/wiki/Broughton_Suspension_Bridge A quote: "On 12 April 1831, the 60th Rifle Corps carried out an exercise on Kersal Moor under the command of Lieutenant P. S. Fitzgerald, the son of John Fitzgerald. As a detachment of 74 men returned to barracks in Salford by way of the bridge[6] the soldiers, who were marching four abreast, felt it begin to vibrate in time with their footsteps. Finding the vibration a pleasant sensation some of them started to whistle a marching tune, and they began to "humour it by the manner in which they stepped", causing the bridge to vibrate even more.[6] The head of the column had almost reached the Pendleton side when they heard "a sound resembling an irregular discharge of firearms".[6] Immediately, one of the iron columns supporting the suspension chains on the Broughton side of the river fell towards the bridge, carrying with it a large stone from the pier to which it had been bolted. The corner of the bridge, no longer supported, then fell 16 or 18 feet into the river, throwing about 40 of the soldiers into the water or against the chains. As the water was only about two feet (60 cm) deep at that point none of the men were killed, but 20 were injured, including six who suffered severe injuries including broken arms and legs, severe bruising, and contusions to the head."
- papalalu 14y ago
  london's "millennium bridge" mentioned briefly in the first article.. http://www.youtube.com/watch?v=eiaM_LZUsqM http://www.youtube.com/watch?v=eiaM_LZUsqM
- huhtenberg 14y ago
  > troops are ordered not to walk in step, because of the stress it places on the bridge Not really, not because of the "stress." The walking rhythm may match the natural oscillation of the bridge thus resulting in a resonance effect. At least that's what they taught us in high school.
  - lutusp 14y ago
    > The walking rhythm may match the natural oscillation of the bridge thus resulting in a resonance effect. Yes, and that stresses the bridge. If it didn't, there would be no reason to avoid it.
  - ColinWright 14y ago
    I've always been told this, and it's always seemed plausible, but it was declared busted by Mythbusters. Having said that, as quoted elsewhere, the Millennium Bridge across the Thames in London did exhibit resonant swaying as pedestrians crossed it, and extra dampers needed to be added. Added in edit ... Auto-hoist, petard-wise. It seems some people have assumed that I meant that this never happens, and cannot ever happen, simply because it was the subject of a Mythbusters episode in which they declared it busted, even though I then added that something similar has in fact happened in real life. I thought the implication was clear, but obviously not. So let me say more explicitly ... It is clear that people walking on a bridge can cause resonance, it has been seen in real life. http://en.wikipedia.org/wiki/Millennium_Bridge_%28London%29#Resonance http://en.wikipedia.org/wiki/Millennium_Bridge_%28London%29#... http://www.youtube.com/watch?v=eiaM_LZUsqM http://www.youtube.com/watch?v=eiaM_LZUsqM Further, that was a non-extreme case, so it is totally plausible that more vigorous marching, more definite synchronisation, and closer matching to the structure's resonant frequency is not only possibly going to cause problems, but likely to cause problems. It is, however, unlikely that marching will match the resonant frequency. Structures these days don't resonate at 2 Hz. Football stadiums are designed to resonate at above 12 Hz. Further, structures often have explicit energy dissipation system built in to them. Taipei 101, for example, has a tuned mass damper to change the resonant frequencies and help absorb, then dissipate energy (yes, I'm speaking loosely here): http://en.wikipedia.org/wiki/Taipei_101#Structural_design http://en.wikipedia.org/wiki/Taipei_101#Structural_design So yes, I knew all that, and yes, a single Mythbusters episode is not proof of anything, but it does provide a collection of data from which to start forming your own hypotheses, designing your own experiments, and understanding that things aren't necessarily as simple as you thought.
deleted 14y ago
[deleted]
derrida 14y ago
It was the London Millennium Bridge. Here is a video of the effect in action: https://www.youtube.com/watch?v=gQK21572oSU https://www.youtube.com/watch?v=gQK21572oSU Here the problem is attributed to the peoples reaction. The evidence from the metronomes might suggest that it has nothing to do with people. The fix involves changing the natural frequency of the bridge.
alan57 14y ago
I think your assumption is right on. Just try to listen to music when you walk and not end up lock-step with the beat.

by alan_cx 14y ago

lutusp 14y ago

> There is a place in the UK where this happens with spooky regularity with people walking. Sometimes in the military, when crossing a bridge, troops are ordered not to walk in step, because of the stress it places on the bridge. http://en.wikipedia.org/wiki/Angers_Bridge http://en.wikipedia.org/wiki/Angers_Bridge A quote: "As usual in crossing that bridge, the soldiers had been ordered to break step and to space themselves farther apart than normal." More dramatic: http://en.wikipedia.org/wiki/Broughton_Suspension_Bridge http://en.wikipedia.org/wiki/Broughton_Suspension_Bridge A quote: "On 12 April 1831, the 60th Rifle Corps carried out an exercise on Kersal Moor under the command of Lieutenant P. S. Fitzgerald, the son of John Fitzgerald. As a detachment of 74 men returned to barracks in Salford by way of the bridge[6] the soldiers, who were marching four abreast, felt it begin to vibrate in time with their footsteps. Finding the vibration a pleasant sensation some of them started to whistle a marching tune, and they began to "humour it by the manner in which they stepped", causing the bridge to vibrate even more.[6] The head of the column had almost reached the Pendleton side when they heard "a sound resembling an irregular discharge of firearms".[6] Immediately, one of the iron columns supporting the suspension chains on the Broughton side of the river fell towards the bridge, carrying with it a large stone from the pier to which it had been bolted. The corner of the bridge, no longer supported, then fell 16 or 18 feet into the river, throwing about 40 of the soldiers into the water or against the chains. As the water was only about two feet (60 cm) deep at that point none of the men were killed, but 20 were injured, including six who suffered severe injuries including broken arms and legs, severe bruising, and contusions to the head."

papalalu 14y ago
london's "millennium bridge" mentioned briefly in the first article.. http://www.youtube.com/watch?v=eiaM_LZUsqM http://www.youtube.com/watch?v=eiaM_LZUsqM
huhtenberg 14y ago
> troops are ordered not to walk in step, because of the stress it places on the bridge Not really, not because of the "stress." The walking rhythm may match the natural oscillation of the bridge thus resulting in a resonance effect. At least that's what they taught us in high school.
- lutusp 14y ago
  > The walking rhythm may match the natural oscillation of the bridge thus resulting in a resonance effect. Yes, and that stresses the bridge. If it didn't, there would be no reason to avoid it.
- ColinWright 14y ago
  I've always been told this, and it's always seemed plausible, but it was declared busted by Mythbusters. Having said that, as quoted elsewhere, the Millennium Bridge across the Thames in London did exhibit resonant swaying as pedestrians crossed it, and extra dampers needed to be added. Added in edit ... Auto-hoist, petard-wise. It seems some people have assumed that I meant that this never happens, and cannot ever happen, simply because it was the subject of a Mythbusters episode in which they declared it busted, even though I then added that something similar has in fact happened in real life. I thought the implication was clear, but obviously not. So let me say more explicitly ... It is clear that people walking on a bridge can cause resonance, it has been seen in real life. http://en.wikipedia.org/wiki/Millennium_Bridge_%28London%29#Resonance http://en.wikipedia.org/wiki/Millennium_Bridge_%28London%29#... http://www.youtube.com/watch?v=eiaM_LZUsqM http://www.youtube.com/watch?v=eiaM_LZUsqM Further, that was a non-extreme case, so it is totally plausible that more vigorous marching, more definite synchronisation, and closer matching to the structure's resonant frequency is not only possibly going to cause problems, but likely to cause problems. It is, however, unlikely that marching will match the resonant frequency. Structures these days don't resonate at 2 Hz. Football stadiums are designed to resonate at above 12 Hz. Further, structures often have explicit energy dissipation system built in to them. Taipei 101, for example, has a tuned mass damper to change the resonant frequencies and help absorb, then dissipate energy (yes, I'm speaking loosely here): http://en.wikipedia.org/wiki/Taipei_101#Structural_design http://en.wikipedia.org/wiki/Taipei_101#Structural_design So yes, I knew all that, and yes, a single Mythbusters episode is not proof of anything, but it does provide a collection of data from which to start forming your own hypotheses, designing your own experiments, and understanding that things aren't necessarily as simple as you thought.

deleted 14y ago

[deleted]

derrida 14y ago

It was the London Millennium Bridge. Here is a video of the effect in action: https://www.youtube.com/watch?v=gQK21572oSU https://www.youtube.com/watch?v=gQK21572oSU Here the problem is attributed to the peoples reaction. The evidence from the metronomes might suggest that it has nothing to do with people. The fix involves changing the natural frequency of the bridge.

alan57 14y ago

I think your assumption is right on. Just try to listen to music when you walk and not end up lock-step with the beat.