Lateral force measurement method
The lateral force measurement method ( SKM for short or Sideway-force Coefficient Routine Investigation Machine , SCRIM for short ) is a test method developed in Great Britain for measuring the grip of road surfaces made of asphalt , mastic asphalt and concrete . In addition to quality assurance when building new roads, it is also used to assess road surfaces that have been in existence for a long time.
Measurement method
With this measuring method, the side force coefficient is determined by means of a fast moving dynamic measuring vehicle (carrier vehicle is a 7.5 to or larger truck> 12.0 to) using a test device in the right wheel rolling lane. This determination of the side force coefficient reflects the grip of the respective type of surface layer tested. The fast moving dynamic measuring vehicle has a linearly guided measuring device which is installed on the right in the wheel rolling track between the front and rear axles. Depending on the size of the vehicle, water is carried by means of a water tank with a volume of 3.5 m³ to 8 m³. Depending on the speed, a control system guides the water via a hose system to a water guide slide. This water guide slide is lowered with the test device and creates a water film thickness of about 0.5 mm.
The specially non-profiled measuring tire used touches the roadway in such a way that it is pulled over the roadway at a fixed angle of 20 ° to the wheel roll track. In the course of the lowest possible friction in the overall system and the previously described inclination, the combination of a pressure cell is used to measure the force that arises as a result of the friction perpendicular to the wheel axis and that pushes the wheel back in the direction of travel. From the ratio of the measured lateral force and the wheel load can cornering μ scrim (also sideway-force coefficient , short SFC ) can be calculated. The method can only be used for a limited period of time, as technical specifications are specified in the guidelines.
Measuring vehicle
Various computer units that are built into the fast-moving dynamic measuring vehicle can record and save additional sensor parameters. For example, temperature measurements of the water, the air, the road and the sloping, easy-running measuring wheel take place here, which are taken into account in the calculation of the lateral force coefficient.
Such a fast-moving dynamic measuring vehicle is requested by building contractors or private companies and tests a quality control through defined test procedures, which are converted into terms such as acceptance, control tests or at the end of the limitation periods. Due to the design, further developments have been created that enable the size or use in subordinate route networks (light vehicles).
Norms and standards
- Technical test regulations for grip measurements in road construction Part: Lateral force measurement method (TP Griff-StB)
Individual evidence
- ↑ S. Velske, H. Mentlein: Road construction technology . Werner Verlag, Düsseldorf 2002, ISBN 3-8041-3875-6 , p. 261 .