The Millennium Bridge - Essay Example

The movement was caused by an unusual phenomenon, Synchronous Lateral Excitation (London Landmarks, 56). When people walk, they naturally sway a little, which in turn caused the bridge to sway with them. Given that the engineers had not installed any form of dampers, the swaying of the bridge was uncontrollable (BBC online, 2000).

Synchronous lateral excitation is basically when the bridge moves laterally in conjunction with outside forces. In this case, pedestrians walking across the bridge. For the engineers to alleviate this movement, they needed to install a damping system. After discussion of either active or passive damping, they chose passive damping. This form of damping uses viscous dampers that are encased pistons, similar in action to the shocks of a vehicle, to absorb and transfer the movement of the bridge so that the swaying is no longer felt. These viscous dampers reduce the lateral motion. To reduce the vertical motion, the engineers employed tuned mass dampers. These dampers are very simple in their technology, as they are tuned to the frequency of the inertia of the bridge, thus reducing lateral movement (Jones, 87).

The engineers in this case should have taken a closer look at the mechanics of the bridge when they built it. It was likely overlooked as this was solely a pedestrian bridge, and average people do not walk in synchronized steps with each other, simply to cross a bridge. Their solution of the installation of dampers was successful, as the bridge is easily crossed en masse without making its users seasick.