Low noise wearing courses are an effective measure to mitigate road traffic noise emission at its source. In Switzerland, a trend of using so-called semi dense asphalt (SDA) with porosity of 10 to 18% and a maximum grain size 4 or 8 mm has emerged about a decade ago. Despite the initial noise reduction values of -6 to -9 dBA, the acoustical and mechanical lifetime of such pavements remains below expectations. This acoustic ageing is dominated by clogging of the open pores and altering macrotexture due to ravelling. Our preliminary work on small test sections has shown that an accurate grinding of the surface is an effective way to regain up to -5 dBA in noise reduction. Depending on the state of clogging and extension of ravelling at the time of the maintenance, the program may require different intensities of grinding followed by sweeping and high-pressure washing. The purpose of this paper is to put forward a maintenance process that is effective to rehabilitate the acoustic performance of aged SDA wearing courses at large-scale. Two roads that were treated in 2018 with a grinding depth of 1.5 to 3 mm showed positive results with an average gain in noise reduction of -3 dBA, measured with the close-proximity (CPX) method. At each location, the treatment was evaluated by the measurements of grinding depth, CPX rolling noise and visualization of the clogged porosity. Performance of the grinding method depending on grinding depth and impact of the aggregate’s petrography are discussed. Additionally, we monitored the long-term behaviour by sequential CPX measurements. Our first results indicate that the treated surface remains stable and noise level gains are preserved over the available time window of the initial 1-year monitoring phase.