Read this passage and answer the questions that follow.
The Millennium Bridge opened on 10 June 2000 as London’s first new Thames
crossing in more than 100 years. The bridge uses “lateral suspension” – an engineeringinnovation that allows suspension bridges to be built without tall supporting columns. Tens of thousands of people crossed the bridge on its opening day.
The structure wasdesigned to take the weight, but suddenly the bridge began to sway and twist in regular oscillations. The worst of the movement occurred on the central span where the edge of the bridge oscillated through a total distance of 70 mm.
To solve the problem the engineers decided to use damping mechanisms – giant shockabsorbers to limit the bridge’s response to external forces. They decided to use twosystems: viscous dampers, similar to car shock absorbers, and tuned mass dampers.
A tuned mass damper is a large mass stiffened by springs.
