Almost 50 000 SilentTrack dampers have been used on the Epping to Chatswood Rail Line, in the suburbs of Sydney. SilentTrackTM is a dynamic damper developed by Tata Steel which significantly reduces the noise generated by railway traffic. A world exclusive, SilentTrackTM is capable of reducing noise generated by the track itself by an average of 4 to 6 dB(A), depending on the form of the track.
For this new delivery in Australia, the order was placed by Union Rail Group, a joint venture between construction contractors Thiess (Australia) and Hochtief (Germany), and the funding body, Transport Infrastructure Development Corporation of New South Wales. The damper manufacture was split approx 50/50 between existing European supply routes and new supply routes in Australia. The installation was carried out by Union Rail Group, with training and initial supervision by Tata Steel (using staff from Tata Steel’ European installation partner Volker Rail). The Epping to Chatswood railway line is a new commuter route which partly runs on slab track through tunnels. Noise control was needed for neighbouring properties, and to reduce in-train noise on the slab track sections. New SilentTrackTM damper moulds have been made to suit the new AS 60 rail profile. The Tata Steel system was one of a number of potential solutions that were trialled by the Client in November 2008. A programme of on track testing showed that SilentTrackTM was the most effective solution to reduce rail generated noise, and one that was also efficient to install during the short track closure periods available. As part of the contract requirements, the performance of the damper system was measured at several locations. In each case it exceeded the Client’s requirements for track decay rate improvement. Following successful installation, the Client placed a follow on order for an additional small stretch of track. Installation of this will take place early in 2010. SilentTrackTM is a vibration damper made of elastomer and steel which is laid on both sides of the rail web. SilentTrackTM absorbs rail vibrations generated by railway traffic and thus reduces the intrinsic noise. This system can be used on both new and existing track. SilentTrackTM uses two steel weights whose size and shape are tailored for a given range of frequencies and track conditions . Says David BENTON, Product Manager at Tata Steel Rail: “The main difficulty in developing the damping system was to be able to reduce noise levels across the wide frequency spectrum – ranging from around 600 hertz to several kilohertz. Rail noise is in the lower half of the range – up to around two kilohertz – and wheel noise is typically in the higher frequencies.” SilentTrackTM is thus synonymous with a tailor-made solution, and adapts ideally to each operating condition, taking into consideration data such as train type, traffic frequency, rail type and rail fastenings. The Tata Steel rail division engineers, after determining the acoustic frequency bands in which action is necessary, can apply damping precisely at the appropriate place for maximum effectiveness.