Millennium Bridge, London people walking caused small sideways oscillations in the bridge, which in turn caused people on the bridge to sway in step, increasing the amplitude of the bridge oscillations and continually reinforcing the effect. On the day of opening, the bridge was crossed by 90,000 people, with up to 2,000 on the bridge at any one time. Resonant vibrational modes due to vertical loads (such as trains, traffic, pedestrians) and wind loads are well understood in bridge design. In the case of the Millennium Bridge, because the lateral motion caused the pedestrians loading the bridge to directly participate with the bridge,
London Bridge William IV and Queen Adelaide attended a banquet in a pavilion erected on the bridge. In 1896 the bridge was the busiest point in London, and one of its most congested; 8,000 pedestrians and 900 vehicles crossed every hour. It was widened by , using granite corbels. Subsequent surveys showed that the bridge was sinking an inch (about 2.5 cm) every eight years, and by 1924 the east side had sunk some three to four inches (about 9 cm) lower than the west side. The bridge would have to be removed and replaced. In 1967, the Common Council of the