Armored elastomeric bearings, pot bearings and shock absorbers are used in the construction of road and railway bridges for their damping action and for safety reasons. Bridge bearings are often made from chloroprene rubber such as Baypren® or from a blend based on natural rubber, into which one or more steel reinforcing layers are incorporated and which can also be strengthened by means of external steel reinforcing plates. These components can absorb vertical loads, horizontal movements and torsion around all axes.

It is not only the commanders of military columns who know just how easily even foot traffic can cause a bridge to sway dangerously. The builders of the Millennium Bridge in London also came to this realization – albeit only after painful experience: The foot bridge in the east of London was opened in a blaze of publicity in June 2000, but when the first pedestrians crossed the suspended structure the architectural masterpiece began to sway so badly that it had to be closed just a day after the opening.

Only after the installation of 91 horizontal and vertical shock absorbers, costing the equivalent of US$ 8.9 million, could the bridge be reopened some two years later. The vibration dampers are viscous dampers, in which rubber is used to prevent dirt, dust and moisture from penetrating the open reservoirs, which are filled with a viscous fluid or com- pound. The damping action is achieved by means of a piston which extends into this compound from above and can generally move in a vertical and a horizontal direction. The damper is rather like a jar of honey into which a teaspoon is dipped.