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Fewer accidents on M4 after surface dressing
Page 47
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• Skidding accidents can be significantly reduced by giving road surfaces a special skid-resistant finish.
In a TRRL study of the elevated section of M4 it was found that the surface coefficient of friction had dropped since laying in 1965 to between 0.35 and 0.45 at 50 kph (30 mph). The surface was subsequently treated in the summer of 1969 and during the next three years the coefficient remained at between 0.50 and 0.60.
In the two years following treatment a 45 per cent reduction in the total number of accidents in which skidding was reported to have occurred emphasized the close relation between resistance to skidding and the accident rate on busy roads. The fact that the higher grip surface was applied to an existing road shows that almost any road could benefit from similar remedial treatment.
Copies of the full report -TRRL Report LR 542, effect of resistance to skidding on accidents, surface dressing on elevated section of M4 motorway — may be obtained by writing to the Director. Transport and Road Research Laboratory, Crowthorne, Berks.