Eight years of thin noise reducing asphalt layer monitoring in an urban environment

The City of Antwerp initiated a pilot project on thin noise reducing asphalt layers in an urban environment with the aim to investigate the behavior of the asphalt layers from a noise perspective with respect to urban traffic without neglecting the mechanical durability. Five thin asphalt layers were selected and compared with a reference section. The pavements were constructed in October 2016 on two different test sites. The construction was followed up extensively. The acoustical quality of the thin asphalt layers is followed up in time. Close-ProXimity (CPX) measurements are performed according to ISO 11819-2 within certain time intervals after construction to follow up the evolution. Texture measurements according to ISO 13473 are linked to the noise measurement results. Visual inspections are performed at regular intervals. The results of eight years of monitoring are discussed. While some test sections are already partially replaced, others are still in acceptable condition. The major concern in the STOLA project is to learn about a good balance between the noise reducing capacity of the chosen thin asphalt layers, a limited degradation of the noise performance during its lifetime and a good mechanical performance delaying ravelling and texture changes as long as possible.