[holding answer 30 November 2009]: Typical noise levels created from either in-service concrete or low-noise surfaces cannot be readily defined. Noise levels created by individual surfaces, even for the same surfacing material type, can vary widely as they are influenced by factors such as age of the surface and its texture depth wear.
Whenever major maintenance is carried out on the strategic road network in England, a low noise surfacing is specified. The Highways Agency specification requires low noise surfacing materials to be at least 2.5dB(A) quieter than traditional hot rolled asphalt surfaces.