Mitigation Made to Measure

Noise and Vibration Specialist Engineer, Keith Jackson , offers his insights on vibration mitigation in the railways.

My 30-year career as an acoustic engineer has seen me address noise and vibration issues in wide-ranging contexts – from automobile and defence to loudspeakers and racetracks! Now, in my new role as Noise and Vibration Specialist Engineer at Pandrol, I am relishing the opportunity to harness my experience to address the unique issues raised by rail infrastructure.

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Sustainable Urbanisation

The challenges posed by people living close to rail routes is only set to grow in the years ahead. The United Nations anticipates that by 2050, 68% of the global population will be living in towns or cities. This urbanisation must be sustainable and, with rail travel widely accepted as more efficient and environmentally friendly than road, the proximity of people and railways is sure to increase.

Unfortunately, noise and vibration are an inevitable consequence. The contact between steel wheel and steel rail creates air-borne noise and ground-borne vibration, which in turn is converted into secondary noise when nearby structures vibrate in sympathy. With brand new track and rolling stock the problem may be minimal, but as soon as there are even slight defects in either rail or wheel the noise and vibration grow – along with complaints from the local community.

As an industry, we need a step change in the mitigation of noise and vibration to address this growing need.

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Fastenings and Resilience

Pandrol specialises in developing rail fastenings for effective control of ground vibration, targeting reducing excitation frequencies between 20Hz and 200Hz (which cause most nuisance to people living and working close to railways). All our products are dynamically tested under simulated train loads to validate their performance.

Fastening systems that perform particularly well in relation to noise and vibration attenuation include Pandrol’s new low stiffness Bonded DFFs and the Vanguard fastening system, which provides exceptionally low vertical dynamic stiffness for areas that require high levels of vibration isolation. Major cities worldwide, including Madrid, Milan, London and Sydney, have retrofitted it to their railways and achieved reductions in noise levels in buildings of the order of 10 to 12 dBA. The recent development of Pandrol’s DFC Common Interface, which is fully interchangeable with a range of fastenings, now provides the ability to tune non-ballasted track’s noise and vibration performance quickly and affordably for the first time.

Pandrol’s other key focus when developing solutions to mitigate noise and vibration is track resilience – introducing an elastic medium with specific spring characteristics to achieve vibration attenuation. Recent innovations include our groundbreaking Sustainable Resilient Systems range – tailor-made products made from at least 90% recycled rubber granules. Combining quality, performance and sustainability, the Under Sleeper Pad, Under Ballast Mat and Floating Slab Mat have all achieved Environmental Product Declarations in recognition of their low impact on the environment. They also have a 25 year track record, with references such as ADIF, Trafikverket, Saudi Arabia High Speed Line, as well as major urban transit projects such as Sydney, Madrid, and Florence.

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Customising the Future

Pandrol’s products already offer impressive adjustability to meet the specific needs of different types of track, train and urban environment. In the future, we are looking to maximise this by offering fully customised noise and vibration attenuation solutions for our customers.

The starting point for this will be an in-depth survey of the customer’s site using our new on-track testing equipment to measure noise, vibration and track movement. Based on the findings, we will then use our acoustic engineering expertise to assess specific problems with noise and vibration, and design and provide a fully tailored solution.

When it comes to noise and vibration, every stretch of rail is unique. I am excited to see how we can shape the future through Pandrol’s unique, made-to-measure solutions.

Get in touch to find out about how we can work with your track to mitigate noise and vibration.