Articles in Taxonomy

Tools for road managers (for an objective and rational comprehensive approach to road management) – BRRC Synthesis F48/14

Several actors are in charge of constructing and maintaining road infrastructure. They may be regions or municipalities, but also managers of specific facilities such airfield strips, port areas, industrial areas, etc. All of them, however, are faced with the same challenges raised by ageing infrastructures, ever increasing traffic loads, and budget restrictions.

The quality of road infrastructure is important to all actors, but is perceived in different ways:

Quality control of earthworks and (sub)base layers

Both at the European and the global level, exchange and work structures are developing that foster technical progress in earthworks and earthmoving projects. They promote:
- a coordination of practices (establishment of standards institute);
- greater participation in research at the European and global levels;
- the scheduling of conferences for exchanges between professionals.

Longitudinal profile analyser (“Analyseur de profil en long”, or APL) – measurement of the longitudinal evenness of roads

The Belgian Road Research Centre has a longitudinal profile analyser for continuous measurements of the road profile. The measured data can be used to quantify the longitudinal evenness of a road and to calculate inticators such as the coefficient of evenness (CP, which stands for coefficient de planéité in French) and the international roughness index (IRI). Longitudinal evenness is an important factor for the safety and comfort of road users. The high accuracy of measurement makes the APL also suitable for research purposes. The measuring wheel bumps up and down with the relief of the road. This movement causes a change in the angle formed by the wheel-bearing arm in its hinge point. An inert pendulum in the bearing arm transforms the road profile into an electric signal. The angle between the bearing arm and the pendulum is recorded every 5 cm. This allows a graphic representation of the “pseudo-profile” of the road surface. A constant survey speed of 21.6 km/h, 54 km/h or 72 km/h is required.


Statistical Pass-By (SPB) method

Areas of Expertise (1)


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)”.


Components and mix design

On distingue trois phases lors de la formulation des mélanges bitumineux: