The feasibility of using twin-layer porous asphalt surfaces on England's strategic road network

In the UK low-noise surfaces have been in use for over 10 years and are used on the strategic road network. Under the requirements of the EU Directive on the Assessment and Management of Environment Noise (END), there may be a need for the UK Highways Agency (HA) to look to implement noise mitigation measures in addition to those already used to address the demands raised by Noise Action Plans produced under the END. Twin-layer porous asphalt is one such possible measure which has been successfully trialled and/or implemented in Europe and which offers significant noise reduction benefits. TRL has been commissioned by the HA to investigate the feasibility of implementing this surface in the UK, taking into account all associated aspects, e.g. construction, maintenance, performance, resource use, costs, and sustainability issues, based on existing knowledge/experiences outside of the UK and the perspective/views of the UK road surfacing industry. This report details the findings from this study, presenting both the benefits and disadvantages, and sets out the resultant recommendations. (A)