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Highways Agency abandons whisper concrete surfacing

CONCRETE SURFACING for trunk roads and motorways is to be abandoned in favour of quieter, more publicly acceptable thin asphalt surfacings, the Highways Agency revealed this week.

Porous asphalt is also to be shelved as a wearing course following a reappraisal by the Agency of the performance of its preferred road surfacing materials.

The decision comes less than a decade after 'whisper' concrete and porous asphalt were heralded by the Agency as the quiet road surfaces of the future.

Both have lost out to the new generation of thin high performance 'negative texture' bituminous surfacings in the booming low noise wearing course market.

Agency civil engineering group manager Graham Bowskill told NCE this week that whisper concrete 'just wasn't quiet enough' and that porous asphalt was costly, expensive to maintain and had a record of problems.

'Whisper concrete was developed to be quieter than hot rolled asphalt, which it is, ' he said. 'But it's significantly noisier than stone mastic asphalt and the proprietary polymer-modified bitumen systems developed from it. These are a lot cheaper than porous asphalt and just as quiet.'

Porous asphalt and whisper concrete had been seen as the only real contenders for the quiet surface market for almost a decade. Trial sections of both materials have been laid on major trunk roads throughout the UK.

Both were developed in Europe and adapted to meet the UK's more stringent skid resistance requirements. Porous asphalt was claimed to be significantly quieter than whisper concrete as well as cutting spray during periods of heavy rain, but its first major use on the Newbury Bypass was dogged by serious production problems (NCE 19 August 1999).

The concrete roads lobby suffered a serious blow in the Government's 10 year transport plan published last summer. This committed the Agency to installing quieter road surfaces on 60% of the trunk road network within 10 years - and resurfacing all concrete roads in the same period.

The policy was criticised this week by David Jones, director of concrete roads development group Britpave, as pandering to public prejudice. 'The subtle distinction between noisy brushfinished concrete roads and low noise, exposed aggregate, whisper concrete is obviously lost on the politicians, ' he said.

'The four stretches of whisper concrete that have been laid have performed very well, and we hope these will be the last to be resurfaced.'

Jones also criticised the noise test methods on which the Agency's decision was mainly based.

'These are carried out in the dry, but these days roads are more often wet than dry. Tests in the wet may show very different results.'

But the high performance surfacings developed by companies like Tarmac, RMC and Aggregate Industries appear to offer so many advantages that whisper concrete appears to have no real future with road operators.

This week Tarmac's Masterflex and Masterphalt P thin surfacings are due to be among the first to be approved under the new Highways Authority Product Approval Scheme run by the British Board of Agrement after more than two years of trials.

With a track record on 80 trial sites around the UK, these new generation wearing courses are set to sweep the market.

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