The Millennium Bridge, officially known as the London Millennium Footbridge, is a steel suspension bridge for pedestrians spanning 144m across the River Thames in London, England. Once opened in June 2000, the structure began experiencing problems with too much movement. This was caused by a “positive feedback” phenomenon where the natural sway motion of people walking would cause small sideways oscillations in the bridge, which in turn caused people to sway in step, increasing the amplitude of these oscillations and reinforcing this effect.
To counterbalance this, Cleveland Bridge were contracted to design and fit a dampener system to make the structure more secure. Once all dampener systems were in place and after a period of testing, the bridge was successfully re-opened in February 2002.