Brief Communication | Published:

Theoretical mechanics

Crowd synchrony on the Millennium Bridge

Nature volume 438, pages 4344 (03 November 2005) | Download Citation



Soon after the crowd streamed on to London's Millennium Bridge on the day it opened, the bridge started to sway from side to side: many pedestrians fell spontaneously into step with the bridge's vibrations, inadvertently amplifying them. Here we model this unexpected and now notorious phenomenon — which was not due to the bridge's innovative design as was first thought — by adapting ideas originally developed to describe the collective synchronization of biological oscillators such as neurons and fireflies. Our approach should help engineers to estimate the damping needed to stabilize other exceptionally crowded footbridges against synchronous lateral excitation by pedestrians.

Footbridges start to sway when packed with pedestrians falling into step with their vibrations.

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Author information


  1. *Department of Theoretical and Applied Mechanics, Cornell University, Ithaca, New York 14853-1503, USA

    • Steven H. Strogatz
    •  & Daniel M. Abrams
  2. †Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, UK

    • Allan McRobie
  3. ‡University of Maryland, College Park, Maryland 20742, USA

    • Bruno Eckhardt
    •  & Edward Ott
  4. §Fachbereich Physik, Philipps-Universität Marburg, 35032 Marburg, Germany

    • Bruno Eckhardt


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Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Steven H. Strogatz.

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