This project subsidized by the Belgian Bureau for Standardization NBN (1st October 2008 – 30th September 2012) was devoted to the development of performance tests for thin and ultra-thin asphalt layers (with a thickness ranging between 10 and 30 mm), which are increasingly used in Belgium and in other European countries. The research effort related directly to a priority set by European standardization committee CEN TC227/WG1, which intends to develop performance tests and performance specifications for all types of asphalt mixture, and to the finalization of ETAG 16, which describes European guidelines for ultra-thin layers. Several test sections (including those with low-noise surface courses on regional road N19 at Turnhout-Kasterlee) were monitored within this project, to validate the test methods.
The royal decrees of 9th October 1998 and 3rd May 2002 on road humps lay down the requirements and technical specifications to be met by these devices. BRRC has developed for the geometric inspection of “raised traffic calming devices on public highways”, as they are officially named, a method of measurement which allows rapid assessment of their compliance with requirements and specifications.
The law authorizes traffic calming devices with varying geometries and dimensions, but requires that they should be adapted to local circumstances (location, types of vehicle in traffic). As a result, not all specified devices (and, all the more so, those failing to comply with regulations) have the same intrinsic effectiveness in reducing speeds. That is why the choice of a traffic calming device with any ensuing layouts or facilities requires careful reflection on the objectives to be met. To collect objective input for this reflection, the Centre also makes measurements on existing sites, where both geometric data and travel speeds are recorded.
To advance the quality of asphalt and to design durable asphalt mixtures, it is necessary to have good test methods for the evaluation of bitumen and asphalt properties both in the laboratory and on site. The link between the test results and long-term performance is of major importance in this respect. Moreover, uniformity in the test methods is pursued at the European level.