Why measure surface friction?
To ensure acceptable road/runway-conditions for all vehicles to travel safely.
Operational measurements in winter
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.
Functional- or Calibration surface friction measuring is made to test the maintenance level of a runway or road, to test the function of the traffic infrastructure. This measuring is made in order to ensure that a newly constructed or refurbished runway or road has a surface friction within applicable laws, safety guidelines and contract specifications. Functional surface friction measuring is also made on a regular basis, depending on traffic volume, on operational traffic infrastructure in order to establish when maintenance needs to be performed. The main reasons for poor surface friction, also under non winter conditions, are polishing of the infrastructures surface and the buildup of rubber residue from tires. These problems are increased when the surface is wet, and for this reason a water film is applied on the tested infrastructure by the measuring equipment during functional friction testing.