tribo, perhaps you forgot to stress the point that this friction testing is for runway maintenance purposes only and thus has little or no relevance to flight operations except where the runway is declared ‘Slippery When Wet’.
A better operational reference giving a wide range of information on the problems of reduced friction operations are at:-
Winter Operations, Friction Measurements and Conditions for Friction Predictions - Executive Summary
Winter Operations, Friction Measurements and Conditions for Friction Predictions - Main Body
Winter Operations, Friction Measurements and Conditions for Friction Predictions - Appendices A-Z