'Whisper concrete' cuts roar of traffic

People living near major roads may get some relief from the noise thanks to a government decision that road builders should be encouraged use "whisper concrete".

The Highways Agency, the Government body responsible for building and maintaining Britain's major roads, has approved the use of the less noisy road surface.

Contractors will be able to include whisper concrete as an option for all roads where concrete is technically suitable but it will be up to contractors, rather than the Highways Agency, to select the specification.

However, the cost of the concrete is about 10 per cent higher than conventional surfaces and this may deter some contractors. A spokesman in the Highways Agency said that the relative prices depended on the availability of aggregate in the particular area.

The Agency will, however, make whisper concrete mandatory for roads carrying 75,000 vehicles or more per day, and for those in noise-sensitive areas.

The new type of concrete has been tested on two roads, the M18 in Yorkshire and the A50 in Derbyshire and the agency found that no additional maintenance costs resulted from its use, despite the harsh winter conditions earlier this year.

On average, noise levels are about two decibels lower for light vehicles and one for heavy vehicles. While this does not sound much, a drop of three decibels in the average noise would be equivalent to halving the traffic flow.

Whisper concrete differs from conventional concrete surface in that some of the aggregate is left exposed, rather than brushed into grooves, which results in less noise. This is because there is random contact between tyre treads and the exposed aggregate. The new surface has been shown to be just as skid resistant as older types.