Road Surfacing (Hansard, 7 December 1999)

§ Mr. Hill

I have asked the Chief Executive of the Highways Agency, Mr. Peter Nutt, to write to my hon. Friend.

Letter from Richard Thorndike to Mr. Bob Blizzard, dated 7 December 1999: You recently asked the Secretary of State for the Environment, Transport and the Regions what assessment he has made of the value of porous asphalt roads surfacing as a means of reducing spray in wet weather. I am replying in the absence of the Chief Executive, Peter Nutt. Research undertaken by the Highways Agency has assessed the value of using porous asphalt road surfaces, including the benefit of reduced spray. Work carried out in the 1980's has shown that porous asphalt can reduce spray by as much as 95 per cent. compared to conventional asphalt when new. This reduces to approximately 30 per cent. after about three years due to the clogging of the porous asphalt from road detritus. The reduction in spray and the better visibility it offers drivers in wet weather, could be expected to reduce accidents when using porous asphalt compared with conventional surfacing. However, surveys carried out for the Highways Agency indicate that vehicles travel faster on porous asphalt in the wet than on conventional surfacing which increases the risk of accidents. This work is supported by an extensive accident survey report from the Netherlands. Where porous asphalt is widely used. Their survey demonstrates that porous asphalt was no safer than conventional 478W surfacing. This was attributed to motorists driving at higher speeds on porous asphalt than conventional surfacing due to reduced spray and better visibility. The results of limited work undertaken by the Highways Agency are consistent with evidence collected in Holland. As part of a strategy to reduce impact of road noise the Highways Agency is carrying out research into alternative types of low noise road surfacing. As a result, new types of surfacing are now being introduced, some of which are often confused with porous asphalt, given their spray suppressing properties. Research on porous asphalt and the new road surfaces is continuing and will include monitoring spray reduction and the benefits offered. If it would be helpful, Graham Bowskill, our Head of Civil Engineering, would be pleased to discuss the performance of porous asphalt and other road surfacing with you. His telephone number is 0171 921 4746.