A FRENCH-DEVELOPED rubber-based alternative to porous asphalt for low-noise road surfacing has failed after only six weeks on trial in Surrey.
About 10,000m2 of the asphaltic concrete surfacing, which uses chipped car tyres as part of the aggregate, were laid on the A240 in Ewell at the beginning of November.
Surrey County Council principal highways maintenance engineer George Kovacs said problems began soon after. 'Holes started to appear all over the area. These have been made safe until the road can be resurfaced.'
Called Colsoft by its supplier Colas, the surfacing is said to reduce tyre noise by more than 5dB(A) compared to conventional asphalts.
Other claimed advantages include less light reflection in wet conditions and environmental friendliness through its use of recycled tyres. And unlike porous asphalt, Colsoft does not become clogged with dirt and debris.
Colas says Colsoft has been used in France since 1994. The following year, the French Ministry of Environment gave the surfacing its Golden Decibel Award. Colas business manager Brian Hicks said Colsoft had been on trial at the Transport Research Laboratory since last July.
'That trial has been 100% successful,' Hicks added. 'But the surfacing at Ewell was laid during unfavourable weather, at the extreme of the recommended conditions.'
Hicks said Colas hoped to identify the cause of the problem within three weeks, and would relay the area in the spring at no cost to the local authority. 'But we will use Colsoft again as we have complete faith in the product.'