Ireland's State of the Environment Report 2024

75 Chapter 3: Environmental Noise Department of Transport, have a key part to play and should actively work to incorporate measures for noise reduction and mitigation for national roads into local authority noise action plans, including considerations around low-noise road surfaces (Topic Box 3.3). Topic Box 3.3  Low-noise road surfaces The interaction between tyres and the road surface is generally one of the most common sources of traffic noise. Noise-reducing road surfaces, such as porous asphalt, can have significant benefits in reducing noise. In Ireland, we sometimes categorise stone mastic asphalt (SMA) of 12-14 mm diameter as a low road noise surface, but this is not in line with the CNOSSOS-EU categorisation in which a low road surface should have an SMA stone grading of 6-8 mm. TII has published interim CNOSSOS-EU road surface correction factors (TII, 2022) based on research undertaken on three common road surfaces used on national roads in Ireland. The research shows that all three surfaces result in noise emissions above those of the CNOSSOS-EU reference surface. For comparison, the SMA 10 mm surfaces currently in use in the Netherlands’ strategic road network may be up to 6 dB less noisy (Shilton et al. , 2023) than the Irish road surfaces examined. Given the link between road surface type and noise generation, this is an area that merits further research in the Irish context. A national noise strategy would drive improvements In Ireland, noise is often regarded as a forgotten pollutant. As demonstrated in the 2018 WHO noise guidelines, excessive noise is an important public health issue, while the round 4 noise maps have clearly shown that road noise, particularly in the larger urban areas, is affecting a significant portion of the population. In this context, a national noise policy statement or strategy has the potential to provide the framework within which integrated noise measures could be identified and promoted across government, industry and society. The national noise strategy could also consider a cross- sectoral approach to noise pollution. Strategies that may be effective for mitigating both environmental noise and air pollution from transport include traffic calming measures, improvements in cycling and walking infrastructure, the use of environmentally friendly vehicles, urban planning measures, improvements in public transport and increases in greenery, and the use of energy-efficient buildings. Overall, in the transport noise area there is also a need for clarity about the funding available for noise mitigation measures, about the responsibility for measures for national roads identified in the noise action plans, and about linking the plans to a national strategy for environmental noise and the development of noise planning guidance. These systemic issues and uncertainties make it challenging for local authorities to progress their noise action plans.