Traffic noise accounts for 66% of the total noise generated outside dwellings in the UK, with 32 million people being exposed to high levels of noise (55 - 75 decibels).

With traffic levels still going up, road noise will become an increasingly serious problem. Traffic noise is caused by engine noise and the vibration of tyres on the road surface. Particularly at speeds of over 40mph vibration from tyres on the road surface is dominant.

Quieter Road Surfaces

Improved Quieter Road Surfaces can reduce noise by 4 - 8 decibels - the equivalent of more than halving the volume of traffic. Noise-reducing modern asphalts are the most effective way to reduce traffic noise at source.

The material is laid in such a way as to achieve a very even running surface which reduces tyre vibration. Conventional types of road surface use projecting aggregate (crushed stone) to provide skid resistance. These projections cause tyre vibration which produces noise.

Modern asphalts have a 'negative texture' with skid resistance provided by gaps in what is otherwise an even surface resulting in minimum tyre vibration and a dramatic reduction in traffic noise.

The magnitude of noise reduction achieved by modern asphalts has been established in a number of independent research exercises. Trails by the Transport Research Laboratory have shown that, compared to conventional asphalts with roll-in chippings, modern asphalt is quieter by about 4 decibels in dry conditions and 8 decibels in the wet.

Compared with brushed concrete surfacing, the benefit increases even more, up to 11 decibels quieter in certain circumstances. According to the Highways Agency, a reduction of 3 decibels is equivalent to either halving the volume of traffic or doubling the distance of the listener from the road.

Lower Speeds

Lower speeds can bring about a reduction in noise levels. Research from the Conservation Law Foundation, based in Boston, Massachusetts, showed that a 12-15mph increase in speed results in noise levels rising by 4-5 decibels.

This doesn't apply when speeds are lower than 35-40mph when most of the noise is created by the engine. However, a car travelling at 31mph makes one-tenth as much noise as one going at 56mph.

The noise from vehicles moving at speed is particularly noticeable in rural areas where the speed limit on most roads, other than motorways, is 60mph.

Traffic calming has become common in urban areas. It is usually done for safety reasons. It can increase noise levels if it results in more 'stop/go' vehicle movements. High quality traffic calming, though, that reduces the number of vehicles using a road and is designed to ensure the smooth running of traffic, can cut both casualties and noise levels.

Less Traffic

Traffic volumes have risen dramatically over the past three decades. They continue to rise, particularly in rural areas, despite government efforts to encourage local authorities to stabilise or reduce traffic in their areas – government now requires local authorities to reduce traffic on their local roads, but, so far, has shied away from national traffic reduction policies.

The Prime Minister has advocated the creation of 'liveable' streets and the Government has earmarked over £300 million for Home Zones (play streets).

It is likely that measures such as these will result in quieter 'residential' streets. Main roads will remain a problem.

That means socially-excluded communities will continue to be particularly hard hit as they live, in disproportionately large numbers, adjacent to main roads.

Poor Show, a study carried out in the London Borough of Greenwich and published in 1997 by ALARM UK and GASP (Greenwich Action to Stop Pollution), found that 21% of council tenants in the borough rated traffic noise as big a problem as crime.

UKNA 2005

For more information contact: the Refined Bitumen Association (on quieter road surfaces), 14a Eccleston St, London SW1W 9LT tel 020 7730 1100; the Slower Speeds Initiative, PO BOX 19, Hereford, HR1 1XJ tel 0845 345 8459; the Council for the Protection of Rural England, 128 Southwark Street, London SE1 OSW tel 020 7981 2800 or, for info on noise compensation, DEFRA, tel: 08459 33 55 77 or email: helpline@defra.gsi.gov.uk or The Highways Agency, Traffic Safety & Environment Division, 0300 123 5000

UK Noise Association, PO BOX 551

Chatham, Kent ME4 9AJ

Tel: 01634 863 852 www.ukna.org.uk info@ukna.org.uk

Information Sheets: Traffic Noise

0300 123 5000