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 Mayor's charity Appeal and to mark the 800th anniversary of Old London Bridge's completion in the reign of King John, the Lord Mayor and Freemen of the City drove a flock of sheep across the bridge, supposedly by ancient right. On 3 June 2017, London Bridge was the target of a terrorist attack. Three Islamist terrorists used a rented van to ram pedestrians walking across the bridge, killing three. The attackers then drove their vehicle to nearby Borough Market, where they stabbed multiple people, five of whom died. Armed police arrived on scene and shot the three suspects dead. In