Stationary skid resistance measurements on road surfaces are carried out using the combined skid resistance tester (in accordance with TP Griff-StB (SRT)) and the outflow meter (in accordance with DIN EN 13036-3). The SRT device measures the friction between a sliding body and the wetted test surface and provides a standardized value of the grip. The outflow meter determines the outflow time of a defined volume of water, which is used to measure the roughness of road surfaces and thus allows conclusions to be drawn about the skid resistance of the road surface.