Stations are busy places.
And when refurbishment and alterations are taking place, and parts of the concourse and platforms have disappeared behind hoardings, the remaining areas get even busier. Now add into the mix the noise of those building works and the whole experience of using that station can become quite unpleasant. Wooden hoardings and wire-mesh “Heras”-type barriers are all very well for keeping the travelling public away from the danger zone, but they do nothing to reduce the noise.
Step forward Peter Wilson. As an engineer with 30 years of experience in acoustics, Peter has an unusually pragmatic approach to the specialist fields of noise and vibration. He also developed the IOSH competency training courses in both noise and vibration. Peter realised that a quick, simple and low-cost solution to this very pervasive noise problem was called for. Too expensive, and it wouldn’t be used. Too difficult to use, and the new technology would not be widely adopted to the benefit of customers, staff and contractors.
Acoustic panels So Peter and his team developed a noise-absorbing panel made up of two elements, a mass layer and a carefully designed acoustic absorbent layer. These not only attenuate the direct transmission of sound, but also reduce the sound reflected back towards the source to improve the overall performance. The two layers were then shaped into strong, flexible barriers and the Echo Barrier was born. These lightweight panels are very easily installed onto fencing using specially designed hooks and eyes. In fact, the first product launched, the Echo Barrier H1, was specifically sized to fit onto standard Heras fence panels, although it can also be easily fitted to wooden hoardings and other structures. The barriers are weatherproof and fire retardant, include reflective strips for night time safety and can also be printed with site messages or advertising.
London Underground Balfour Beatty Rail was quick to pick up on the new product and use it on projects for London Underground. Clipping Echo Barrier panels onto barriers markedly reduced the noise from their work and inconvenience to both neighbours and the travelling public. As Martin Higgins, Project Manager at Balfour Beatty Rail commented: “This product, and what it allows us to do, has had a considerable positive impact on our reputation and on our procedures. It will prove a valuable asset moving forward in ensuring that we are able to respect the communities in which we do our work, and are able to work more efficiently and effectively.” The configuration or layout of acoustic barriers with respect to the relevant noise source is a key factor in achieving the required noise reduction.
There are two simple principles involved. The first involves maximising the sound ‘shadow’ cast by the barrier by positioning the barrier correctly. The second is that the performance of any barrier, whether a temporary construction or a brick wall, is always significantly less at lower frequencies. This effect is created by a combination of the barrier geometry and the laws of physics.
Technically, lower frequency sound has a longer wavelength which reduces the effective height of the barrier, creating a smaller acoustic ‘shadow’. As well as supplying the product, Echo Barrier can advise on how best to use it. So if a particular application involves unusual noise signatures or geometries, or the need to be able to guarantee specific noise levels, they can provide a full range of additional technical support services.
Other benefits And passenger comfort is not the only benefit. As one London Underground project manager observed: “The costs of the noise control measures range from £2,000 to £6,000 per weekend. Considering that a noise abatement notice could jeopardise a £1 million contract for a weekend track renewal project, the mitigation costs are very low.”
The benefits of using Echo Barrier have also been recognised by no-less an organisation than the Noise Abatement Society.
At their 11th annual awards, which acknowledge innovative ideas that have made a positive impact on the reduction of excessive noise in the community, Echo Barrier was highly commended in the Technology category, sponsored by the Institute of Acoustics. So next time you walk past some station rebuilding works, listen out for the Echo Barrier!