Data from: Walking crowds on a shaky surface: stable walkers discover Millennium Bridge oscillations with and without pedestrian synchrony

Why did the London Millennium Bridge shake when there was a big enough
crowd walking on it? What features of human walking dynamics when coupled
to a shaky surface produce such shaking? Here, we use a simple biped model
capable of walking stably in 3D to examine these questions. We simulate
multiple such stable bipeds walking simultaneously on a bridge, showing
that they naturally synchronize under certain conditions, but that
synchronization is not required to shake the bridge. Under such shaking
conditions, the simulated walkers increase their step-widths and expend
more metabolic energy than when the bridge does not shake. We also find
that such bipeds can walk stably on externally shaken treadmills,
synchronizing with the treadmill motion for a range of oscillation
amplitudes and frequencies, sometimes performing net positive work on the
treadmill. Our simulations illustrate how interactions between (idealized)
bipeds through the walking surface can produce emergent collective
behavior that may not be exhibited by just a single biped.