STOCKS OF high performance skid resistant aggregate will run out within 15 years unless local authorities adopt more sustainable road surfacing policies, government consultants warned this week.
Capita Symonds is to put proposals to limit the use of high performance aggregates to a series of workshops next week.
It will suggest that councils restrict their use to hazardous junctions and high speed roads, where risks of serious accidents are greatest.
In speed restricted areas lower performance aggregates should be used, preferably from local sources.
The Office of the Deputy Prime Minister has commissioned Capita Symonds to examine more sustainable uses of high Polished Stone Value (PSV) aggregates in roads.
Local authorities are expected to resist the call to restrict use of these materials.
They tend to specify the highest possible skid resistance everywhere out of fear of litigation from road accident victims.
'The advent of thin high performance surfacings and the virtual demise of hot rolled asphalt (HRA) means the use of high PSV aggregates has to be reassessed in terms of sustainability, ' Capita Symonds head of earth sciences Dr Alan Thompson said.
'Unlike HRA, these new surfacings use high specification aggregates (HSA) throughout their depth. The increase in demand means that we only have another 15 years of permitted extractions left'.
Most HSAs come from northern England and Wales.
Some of the quarries are in national parks.
Thin toppings use a smaller nominal aggregate size than HRA, which makes more efficient use of the quarries' output, but the extra crushing needed consumes more energy and can cause a lot more dust.