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 station to the Big Four grouping in 1923. All of the railways of southern England combined to form the Southern Railway (SR), bringing the London Bridge complex under single ownership. The wall that divided the Chatham and Brighton stations was partially knocked through in 1928 to provide an easier interchange between stations. This allowed a greater range of platforms to be used for the increasingly frequent suburban rail services to London Bridge. Between 1926 and 1928 the Southern Railway electrified the SE&CR suburban lines at London Bridge using a third rail system, adapting the existing LB&SCR routes to it at the