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 used are 150 to 200 millimetres (6 to 8 inches) thick. Some of the stones from the bridge were left behind at Merrivale Quarry at Princetown in Devon. When Merrivale Quarry was abandoned and flooded in 2003, some of the remaining stones were sold in an online auction. The current London Bridge was designed by architect Lord Holford and engineers Mott, Hay and Anderson. It was constructed by contractors John Mowlem and Co from 1967 to 1972, and opened by Queen Elizabeth II on 17 March 1973. It comprises three spans of prestressed-concrete box girders, a total of long. The