Revisiting the pedestrian-induced lateral vibration of footbridges and crowd synchronization problem

The problem of pedestrian-induced vibration of footbridge came to our attention in Japan in 1989 when a cable-stayed footbridge named Toda Bridge showed a peculiar type of lateral vibration during the passing of congested crowd. Synchronization among the crossing pedestrians and the structure was observed on several occasions. When the research was published in 1993, it did not really attract much attention since only few footbridges on the other parts of the world had shown similar phenomenon before. Several years later, public attention worldwide increased significantly when the Solferino Bridge in Paris and the Millennium Bridges in London showed the similar lateral vibration during the passing of congested crowd. The two incidents mark the beginning of extensive study on the phenomenon that results in considerable number of research, experiments, published reports and design guidelines. Now, almost twenty five years from the time of Toda Bridge incident, our knowledge on the problem has improved significantly. This paper attempts to provide a review on developments of studies on pedestrian-induced lateral vibration of footbridges in the past two decades. Focuses are given on the development of pedestrian load modelling, excitation mechanisms, vibration countermeasures design guidelines, current achievements and the remaining challenges.