A Conceptual Review of Pedestrian-Induced Lateral Vibration and Crowd Synchronization Problem on Footbridges

Abstract

Modern footbridges are often characterized by architectural demands for light, slender, and long structures that may lead to excessive vibration problems. In past decades, occurrences of pedestrian-induced vibration on footbridges have been reported, notably at the Toda Bridge in Japan, the Millennium Bridge in London, and the Solferino in Paris. In 1989, we observed a peculiar type of lateral vibration at the Toda Bridge during the passing of congested crowds. Hundreds of pedestrians walked in a synchronized manner among themselves, which created remarkable lateral vibration in the structure. Approximately 10 years later, public attention on pedestrian-induced lateral vibration increased significantly when the Solferino Bridge in Paris and the Millennium Bridge in London showed a similar phenomenon during the passing of congested crowds. These three most well-known cases have triggered extensive study, and pedestrian-induced vibration has emerged as an important topic in vibration study. A considerable amount of research, experiments, published reports, and design guidelines on this topic has been produced over the last two decades. The intriguing questions regarding the phenomenon are, how do we formulate lateral pedestrian force, and how do we conceptualize excitation and synchronization mechanisms? To find the answers, many models have been proposed and validated numerically or experimentally. This paper is aimed at providing a critical conceptual review on the development of studies on pedestrian-induced lateral vibration of footbridges. Focus is placed on the development of pedestrian load modeling, the conceptualization of excitation and synchronization mechanisms, design guidelines, and vibration countermeasures.