Literature reviewIntroductionLateral vibrations induced by pedestrians on footbridges have been observed for several decades. More recently, long span footbridges around the world have experienced unacceptable levels of lateral vibration, and more locally, the Paris Solferino and London Millennium bridges were in 1999 and 2000 respectively. As a result, research has been carried out into the causes of this phenomenon. lateral vibrations, and in particular, to a phenomenon called “synchronous lateral excitation” (SLE), in which, under certain pedestrian loading conditions, a sudden and abrupt increase in bridge vibrations occurs. In particular, the London Millennium Gateway became a high-profile case and attracted much publicity, and its subsequent investigation and solution was widely monitored and publicized. Extensive testing and resulting data and analysis were carried out with respect to the structure, crowd loading effects and pedestrian modeling with respect to the vibration effects of the structure, providing accessible data to the public. Since this event, more attention has been drawn to other similar experiments with gateways and has resulted in more in-depth research on the subject. Since 2000, the number of articles published in this decade on this topic has increased more than eightfold compared to the previous decade, Venuti and Bruno (2009). It also highlights the possibility of potential problems for bridges that may not yet have experienced high levels of pedestrian loading. London's Millennium Gateway Examining some of the issues with this gateway will identify areas for study and the investigation will be examined in more detail at a later date. on. The bridge opened in June 2000 and the experiment... middle of paper ...... driven laterally in a sinusoidal manner at selected frequencies and amplitudes. The tests performed indicated force peaks at the walking frequency and its harmonics, but also indicated an additional frequency, called self-excited force. He was also able to identify that pedestrians were acting as a negative force, effectively dampening the structure over a range of frequencies with a significantly high incidence. More extensive testing was carried out more recently by Ingolfsson[], using the same treadmill, but for more pedestrians and a greater range of frequencies and amplitudes. He summarized that pedestrians act as negative shock absorbers for most frequencies and add to the overall modal mass at higher frequencies but decrease it at lower frequencies. The large variation in measurements, however, prevents a deterministic description of the data from being made..