On 24th August 2015, about seventy delegates from fifteen countries gathered in BRRC’s auditorium at Sterrebeek to attend the final PERSUADE seminar (acronym of PoroElastic Road SUrface: an innovation to Avoid Damages to the Environment).
The objective of this six-year European research project (September 1, 2009 – August 31, 2015) led by BRRC was to develop a safe and durable poroelastic road surface, as a means to control road traffic noise.
A poroelastic road surface is composed of rubber granules (from recycled car tyres), small-sized stone aggregate and a number of additives, which are bound with an elastic synthetic resin (polyurethane). It contains no bitumen and must, therefore, not be confused with rubberized asphalt.
Earlier experiments had demonstrated that such a road surface can reduce road traffic noise by 7 to 12 dB. For comparison, a 4 m high noise screen has a noise-abating effect of about 8 dB.
However, durability was inadequate, especially for fretting and adhesion to the underlying layer. Further extensive research was necessary to improve those aspects and to find the answers to a number of pending questions.
This was also a small sequel project to SILVIA, which was funded under the 6th EU Framework Programme. It was carried out by a consortium of BRRC, DRI and FEHRL. The object was to disseminate the knowledge on low-noise pavements gained in the SILVIA project to countries which had not participated in SILVIA. A number of one-day workshops were held in six countries (Slovenia, Romania, Switzerland, Ireland, Portugal, and Greece). In addition, a European working group on the Acoustic classification of road surfaces was formed, which held its first meeting in Ljubljana in April 2008 and its second in Copenhagen in September 2008.
The purpose of this method is to determine the acoustic quality of a given road pavement at a well-defined location. BRRC performs this test according to the specifications given in the relevant standard ISO 11819-1. A sound level meter and a tachometer are installed on the roadside to measure the maximum sound pressure level and the speed of a large number of randomly sampled passing vehicles. The results are statistically processed into an SPB index (SPBI), which is a good measure of the acoustic quality of the pavement at the measuring site – more particularly, of the influence of the pavement on traffic noise load for local residents. A full description of the test can be found in BRRC’s leaflet F67 “La méthode Statistical Pass-By (SPB)”.