A rail damping device which will reduce noise from railway tracks has been developed by scientists at the Institute of Sound and Vibration Research (ISVR) at the University of Southampton and Corus Rail.
The damper tackles the noise which is generated at the wheel/rail interface and can be fitted to a variety of standard rail sections.
The operation of the damper is based on a damped mass-spring system. Steel bars are attached to the rail by a rubber-like material, which acts as a damped spring. This system resonates at a particular frequency and due to its damping effect, energy is lost in the rubber layer. Tests have shown that reductions of the track component of noise of about six decibels can be expected using the damper.
Its developers claim that it is a significantly more attractive option than noise containment measures such as barriers, which are visually intrusive and very expensive.
According to Dr. David Thompson of the ISVR dynamics group, ‘because of the use of a high damping material, it is effective over quite a broad frequency range.’
‘The formulation of the rubber layer is quite critical to the success of the design. To increase the range further a two-layer system can be used with two metal bars and two layers of rubber. Such a system has two resonance frequencies,’ he added.
The system has been further developed for implementation on other standard rail shapes. A Dutch company Volker-Stevin has also helped to refine the installation procedure for the damper.
Test installations have been installed by Dutch Railways at three sites and by French Railways.