Highways Agency Reports

An earlier trial had shown that pervious macadam cannot be effectively cleared of detrtus in the vods by mechanical meansafter severn years trafficking. This trial was carried out on a two year old stretch of pervious macadam which showed that there is only minimal improvement after a single pass at 50 bar, but that the hydraulic conductivity was increased by about 27% after three passes. The use of a hand-held jet at 100 bar showed greater improvements, but the effect of using the equipment at higher pressures, including its potentila for damaging the surfacing, needs to be assessed.