traffic on the highway, surfacing materials can significantly lower noise emissions generated by vehicles. Thin wearing course systems can be significantly
quieter than concrete. It should be noted that, in England, rigid concrete construction is not permitted unless it has an asphalt surfacing. ‘Rigid composite’
denotes continuously reinforced concrete roadbase (CRCR) with 100mm of
asphalt surfacing. A thin wearing course can also be used with a binder course
making up the remaining part of the required 100mm. If porous asphalt is used
over CRCR, it should be 50mm thick over 90mm of binder course, or 50mm
thick over 60mm of binder course with the concrete slab thickness increased
by 10mm