The London Millennium Footbridge Revisited: Emergent Instability Without Synchronization

The pedestrian-induced instability of London’s Millennium Bridge is widely held up as thecanonical example of synchronization in complex networks [9]. The popular explanationmaintained that once the number of pedestrians reached a certain threshold, the pedestrianscould supposedly synchronize their footsteps with each other at the bridge’s naturalfrequency. The result was the onset of dangerous sideways oscillations.