Clamped on masses reduce rail noise up by 6dB

Corus Rail has devised a clamp on damper for railway track that it says reduces noise by an average of 4 to 6dB(A), depending on the form of the track.

Each damper consists of two steel masses in elastomer and a damper is clamped on each side of the rail in between each pair of sleepers and clips. This is sufficient to inhibit up and down vibration in the track. The 'SilentTrack' system has been applied in the form of 50,000 dampers to 16miles of track in a new Epping to Chatswood commuter line in the suburbs of Sydney, Australia. The line partly runs on slab track through tunnels. David Benton, product manager at Corus Rail said: "The main difficult in developing the damping system was to be able to reduce noise levels across the wide frequency spectrum, ranging from around 600Hz to several kilohertz –and wheel noise is in the lower half of the range – up to around 2KHz." Using elastomer mounted masses is a fairly standard way of reducing noise and vibration, but it is not normally applied to rail track. In this instance, however, it was deemed necessary to reduce the noise experienced by neighbouring properties and in the trains themselves, in a way that could be installed during short track closure periods.