International experiment to compare and harmonize the pavement texture and skid resistance measurement methods

This paper summarises the results of an International Experiment to compare and harmonise methods of measuring pavement texture and skid resistance. This work was initiated in 1988 by the PIARC Technical Committee on Surface Characteristics (Committee C1). The tests were conducted in September and October 1992. 54 sites, having concrete surfaces with a wide variety of different characteristics, were selected carefully. 47 devices from 16 countries, for measuring friction and/or texture, were used. The paper presents the main results for comparisons between four main types of devices, and evaluates the repeatability of the measurements. It then describes a proposed International Friction Index, based on three types of friction measuring systems: (1) sideforce; (2) braking force with an unlocked wheel; and (3) braking force with an locked wheel. The four main objectives of the Experiment were met, sometimes more successfully than expected. Resulting benefits include: (1) the ability of road and airport authorities to adapt to a universal scale without having to replace their present procedures; (2) ability of contractors to adapt to specifications based on local control methods; (3) better knowledge of skid resistance; and (4) improved safety.