SKID RESISTANCE / MACROTEXTURE MEASUREMENTS
The skid resistance of a road – especially in wet conditions – is decisive for the driving and braking behaviour of motor vehicles and is therefore significant in the investigation and assessment of accident causes. Furthermore, skid resistance measurements (sub-project 2 according to ZTV ZEB-StB) are an important decision-making basis for maintenance management within the scope of condition monitoring and assessment. Skid resistance measurements are also used in the acceptance of construction measures.
Determination of the sideway force coefficient [Source: TP Griff-StB (SKM)].
In Germany and many other European countries, skid resistance is recorded and evaluated by the fast-driving measuring system SKM (sideway force measuring method).
The sideway force measuring method is defined in the TP Griff-StB (SKM). The measuring principle used here is the measuring wheel that is inclined to the direction of travel and rolls under lateral slip with an inclined running angle of 20°. Since the grip decreases in wet conditions, a defined film of water is applied to the measuring track.
To characterise the road grip, the sideway friction coefficient μ-SKM (SFC) is calculated. This value describes the ratio of the lateral force acting on the measuring wheel due to friction to the normal force of the measuring wheel at a wheel load of 200 kg.
MACROTEXTURE MEASUREMENTS
“The texture of the road surface is the determining parameter for parameters such as noise emission from the tyre contact patch, grip between tyre and road surface, rolling resistance and tyre wear” (EN ISO 13473). Wet grip is also influenced by texture.
The texture, or in other words the roughness profile of the road surface, is determined by the aggregates used in the construction of the road in terms of their shape, size and mixture.
The wavelength and amplitude of the unevenness on the road surface are used as a measure of texture. If the wavelength is in the range of 0.5 to 50 mm, we speak of macrotexture.
Our multifunctional measuring systems ARGUS® and the SKM skid resistance measuring system are used to record the macrotexture. The recording is done via a laser roughness sensor with a high clock rate, which enables the following measurements / evaluations:
