Operational friction measuring is performed mainly in winter conditions in order to answer the basic question "How good grip does the runway or road have at this specific moment?” Knowing how good the surface grip is, surface friction in other words, at a specific moment in time is an essential tool in the operation of traffic infrastructure during winter conditions.This information serves as a guidance to initiate remedying actions such as snow removal, distribution of de-icing chemicals and speed reduction, in order to enable a safe use of the traffic infrastructure. Equally important is to perform operational surface friction measuring after the remedying actions has been made in order to test the outcome and to plan ahead for future actions.