Australian soundproofing solutions company, Pyrotek Soundguard, has taken a brief from Australian-based international consulting firm, Heggies, to help ensure 16 locos bought in Denmark by Independent Railways of Australia comply with local noise standards.
The locos are a substantial addition to Independent Railways’ fleet, which includes a wide range of rolling stock and locomotives from light, short haul engines suitable for branch line work to long haul main line engines suitable for intrastate services.
Although being refurbished in Denmark, the locos are arriving here still with work to be done to meet the noise limits specified in RailCorp licence RSU 150 and EPA licence 12208.
“The requirements of these two licences are very similar, with compliance measurements to be undertaken using procedures consistent with the requirements of Australian Standard AS2377 ‘Acoustics methods for the measurement of railbound vehicle noise,” explains Heggies’ Michael Allan, who performed the noise measurements on the test locomotive.
“The testing includes noise measurements on both sides of the locomotive at a distance of 15 m from the track centreline. To comply, noise from the loco must not exceed 87 dBA and 95 dB linear at 15 m when operating at a constant speed of 80 km/h and for various acceleration and braking scenarios.”
The first raft of tests revealed a low frequency noise problem which was traced to the two floor layers of the locomotive.
As a key component of the final noise reduction outcome Michael Allan sought input from David Smart of Pyrotek’s Soundguard division to come up with a solution to add a significant amount of damping to the floor panels.
Pyrotek Soundguard’s solution was to coat the panels with Soundpaint and lay a floor matting of 8 kilogram per square metre Wavebar.
Soundpaint is a water-based damping compound of synthetic resin and fillers, which, when sprayed or troweled onto metal, plastic and timber surfaces, reduces vibration noise including ringing and tinning of metal structures, and achieving a sound transmission loss of up to 45 decibels.
Wavebar is a flexible composite comprising polyester fabric and barium-loaded vinyl whose mass damps out much of the energy of vibration, even at low frequencies where other soundproofing materials don’t perform well.
“Together these two Soundguard products form a constrained damping layer, which subsequent testing showed was effective in dealing with this aspect of the loco’s problem,” Michael reports.
Independent Railways’ maintenance manager, Wayne Fisher, adds: “Installation wasn’t a problem. We laid the Wavebar floor mat while the second coat of Soundpaint was wet, to serve as an adhesive layer, and then mechanically fastened the lot with screw plates.”
“Five locos have so far been delivered after changes to the frames in Denmark, and removal of equipment needed there but not here. The deal has been two years in the making with the first loco arriving twelve months ago.”
He concludes: “We’re very happy with everything both Heggies and Pyrotek’s Soundguard have done.”