The grip properties of the road surface are a very important indicator from the point of view of traffic safety. We use the Norwegian-made ViaFriction device to measure the grip factor. The device is mounted on a trailer with a water tank and a measuring head with a measuring wheel attached to the rear of the trailer. The working principle of the device consists in measuring the forces generated by the braking of the measuring wheel. When measuring the summer grip factor, the methodology also includes creating a layer of water on the road surface in front of the measuring wheel. When measuring the winter grip factor, a tire with a different pattern is installed on the measuring wheel and water is not used in the measurement.

We regularly calibrate the device in calibration tests organized by the Norwegian Road Administration (Statens Vegvesen), where the reference device is the specially developed device Oscar.

See here for information on measuring the winter friction with the Eltrip measuring device.