The sounds of silence
The mighty Roman Empire stood for many centuries but there were some enemies that even it could not defeat. No, not the Vandals, the Huns or the Visigoths – rather we’re talking train noise.
Some years ago, German authorities in the Upper Rhine Valley faced a conundrum. A UNESCO-World Heritage Roman city wall was being affected by rail noise, noise that was also affecting nearby cafes in this popular tourist region. However, the railway was also one of the key German freight routes from the northern ports into the south and west. Clearly, something had to be done.
Large sound barriers were deemed a poor option, being unsightly and blocking the view of the old roman arch bridge for café goers. An alternative was found, that of a noise attenuation system developed by STRAILastic. This system, involves a panel called the STRAILastic IP, an acoustically optimised rubber plate that can be fitted directly onto existing railing or rail structures.
The noise attenuation system is made from compressed recycled rubber, compressed with a force of about 1200 tonnes and then cooled in a special chamber. It can then be moulded into the small barriers that are placed near the tracks, nullifying the worst noise effects.
“It was enough reduction in noise from freight and passenger trains to allow people to enjoy sitting outside and inside the café near the rail line,” said Andreas Goeschl, STRAILastic Australia operations director.
“The benefit here is that you are placing the noise attenuation system as close as possible to the noise source.
“An additional advantage is that all products are made more or less from recycled material and can be recycled again.”
STRAILastic which manufactures and markets both noise attenuation products and light rail track systems, is part of a business owned by German business KRAIBURG STRAIL (a composite word meaning ‘street meets rail’), which also includes STRAIL Level Crossings and STRAILway which deals in composite sleepers.
All three business divisions operate on the basis of using recycled material. The KRAIBURG Group business employs 2500 employees in total.
All products are made from recycled material and can be recycled again.
“Our material sources are from all over Europe but with strict quality control,” Goeschl said.
“This allows for broad quality sourcing and development of long relationships for the reliability of the materials supply source that are used which we know can be safely handled.”
The noise attenuation system has a core of 70plus per cent recycled rubber and filler materials and is then covered in virgin rubber sheet prior to moulding. This outer layer is treated to resist ultraviolet rays and fire, something that could otherwise lead to deterioration in rubber products.
“We have a special UV cover sheet for Australian conditions that is tuned to higher levels of sunlight and UV light,” Goeschl said.
Advantages of the STRAILastic system is that it can provide noise isolation on both sides of the track and can be installed quite quickly. It also has an anti-graffiti covering and a metal cage to thwart the most determined vandal.
“But a really important point is that you can be installed in existing infrastructure; you don’t need any base or foundation that costs a lot of money and time to install,” Goeschl said.
“Nor do you need a detailed planning approval from governments.
“It is worth noting that If you change the foundations, you may need to seek formal planning approval which takes time, so our system avoids a tremendous amount of hassle and time wasting.”
Offering a “toolbox”
Goeschl said they sought to offer their clients ‘a toolbox’ suite of options for dealing with sound and vibration from railways.
“In Europe, railway operators are required to reduce noise. From a cost efficiency calculation, the more people who benefit from noise attenuation using these types of products, the more funding can be found to assist the railway authorities,” he said.
“We acknowledge you can’t substitute high noise barriers everywhere, but in particular areas, especially where we have embankments that are ideal for our setup or in tunnels with the new high absorbing panels, we are able to show clients all the options.”
The future in Australia?
Strail has been selling its products into Australian railways for more than 40 years . Strailastic product range builds on that experience of providing quality products with a long asset life in the harsh Australia environment. The community want products that utilise and reuse existing materials which can perform as well as being sustainable.
Strailastic has taken a cautious approach since 2018, to building acceptance of their noise attenuation products and light rail track systems across Australia, concentrating initially on the extensive list of new projects for new metro rail and light rail track systems. It was unsuccessful with the Sydney and South East metro extension and It is currently bidding three projects for Metronet in Perth using its new high absorbing noise mini sound wall panels either curved to fit the tunnel profiles of these new rail extensions or as flat panels to fit to the top of bridge parapets on several grade separations where previously large concrete walls typically post and panel walls were used.
Strailastic works closely with acoustic engineers to combine their range of products to cost effectively manage noise attenuation. The noise walls are typically combined with track web dampers as designed to reduce noise levels significantly typically about 50% reduction to the human ear.
“Our heavy web dampers have been installed on the Brisbane Metro network on the Merivale Bridge and on the approaches to the Roma Street tunnel and an 80 metre trial at Waverton on the North shore Line for Sydney Trains.”
Managing the noise from railways is an increasingly an issue in Australians cities and towns along major rail corridors as land scarcity has housing and offices building closer to railway corridors. But the community doesn’t want to see the large graffiti covered concrete walls to manage noise. This product range provides a much more acceptable alternative.
As in other markets around the world, Strailastic will work closely with Australian and New Zealand clients by uses its extensive research and development to work with clients on their particular noise challengers and will look to modify products to suit.
Reducing noise is as important as other sustainability efforts to the quality of the community in which we all live