Environment
TRAFFIC NOISE
Modern asphalt road surfaces can play a significant role in alleviating traffic noise levels experienced by over 32 million people in the UK.
The two main sources of traffic noise are: vehicle engines; and the vibration of tyres on the road surface.
- Modern asphalts can reduce tyre/road surface noise by as much as 11dB(A) more than other road surfaces. (According to the Highways Agency a reduction of 3dB(A) is equivalent to either halving the volume of traffic or doubling the distance of the listener from the road).
- By reducing the noise level at source, modern asphalts are more efficient and cost effective than noise barriers, which deflect the noise elsewhere.
- Modern asphalts are more environmentally friendly than other noise-reducing measures, since the extensive use of barriers, particularly on existing roads, raises problems of visual intrusion.
- The introduction of modern traffic-noise-reducing asphalts on UK roads can also reduce the need, and level of, compensation claims being faced by the Government. One stretch of the A27 near Chichester, in Sussex cost £20 million to build and has generated 2,500 compensation claims costing £22 million.
- The publication of the Government's 10-year Transport Plan in July 2000 makes optimistic reading for those suffering from excessive traffic noise. It states: "quieter road surfaces [will be] installed on over 60 per cent of the network including all concrete stretches."
- In addition, the 10-year plan states that the Government will "secure reductions in noise, dislocation and nuisance caused by traffic through the widespread introduction of low-noise surfaces"
RECYCLING
Asphalt roads are one of the most successful examples of the effective re-use of a finite natural resource. Increasingly economical in their use of new materials, asphalt roads are recyclable.
- Essential maintenance frequently requires replacement only of the topmost layer of the road. Higher-grade surface material can be recycled in situ by being planed off, treated and re-laid during maintenance.
- In-situ recycling plants have the additional environmental benefit of reducing the need for haulage of new or waste material to or from maintenance sites resulting in fewer lorry journeys.
- During more extensive repair, much of the asphalt material extracted can be re-used in lower structural layers.
- Recycled asphalt can also be used for surfacing relatively lightly-used areas such as minor or estate roads, playgrounds or car parks.
CYCLE PATHS
Not just an essential surface for motorised traffic, asphalt is also an ideal surface for sustainable transport such as bicycles.
As part of the National Cycle Network, co-ordinated by civil engineering charity Sustrans, asphalt has created flexible surfacings for what are often unstable bases, particularly in rural areas. In towns asphalt has been used to create coloured lanes to delineate protected routes from motorised traffic in ways that are both safety enhancing and aesthetically pleasing.
The network aims eventually to offer a 10,000km web of safe, high-quality routes to cyclists, half of which will be on traffic-calmed or segregated town and minor country roads, and half on traffic-free paths for joint use with walkers and disabled people.
COLOURED ASPHALT
The use of colour is an extremely important element in modern construction and landscaping, and the availability and choice of coloured asphalts enable specifiers to exploit the functional qualities of these materials while gaining the benefit of additional aesthetic dimensions.