New study sheds more light on what caused Millennium Bridge to wobble

London's Millennium Bridge had issues with excessive shaking and swaying when it first opened in June 2000.

Enlarge / London’s
Millennium Bridge had issues with excessive shaking and swaying
when it first opened in June 2000. (credit: Alberto
Pezzali/NurPhoto/Getty Images)

When London’s Millennium Bridge first opened in June 2000, the
city was alarmed to discover that the motion of crowds of
pedestrians crossing it gave rise to significant shaking and
swaying. Londoners nicknamed it “Wobbly Bridge.” Officials shut it
down after just two days, and the bridge remained closed for the
next two years until appropriate modifications could be made to
stop the swaying.

It’s not an entirely unknown phenomenon: there’s a sign dating
back to 1873 on London’s Albert Bridge warning military troops to
break their usual lock-step motion when crossing. The culprit was
not Millennium Bridge’s design. Rather, it was due to a weird
synchronicity between the bridge’s lateral (sideways) sway and
pedestrians’ gaits.

A
new paper
in Biology Letters sheds further light on this by
simulating the biomechanics of large crowds of people walking on a
bridge. While there have been many different approaches to studying
these fascinating dynamics over the years—including a lab-based
treadmill recreation
of people walking across Millennium Bridge
by Cambridge University engineer Allan McRobie—this is
a significantly improved model of how people adjust their gait
when walking on a wobbly surface, according to co-author Varun
Joshi of Ohio State University. It suggests that one might not
even need synchronization to cause the shaking.

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Source: FS – All – Science – News
New study sheds more light on what caused Millennium Bridge to wobble