Maintaining pavement skid resistance depends on the geometric conditions of the road (straights, curves, slopes, etc.), weather conditions (wet or dry surfaces, etc.), and vehicle conditions (condition of brakes, tires, etc.). This paper reports the criteria adopted in establishing the more probable limit values associated with the various characteristics in question which are necessary to maintain safety without sacrificing economic management criteria.
Skid-resistance measurements, together with riding comfort index values, thus serve two main purposes: (1) In construction or maintenance of pavements, they serve as a means of quality control; pavements are deemed to have been laid properly only if certain characteristics correspond to pre-established acceptance requirements, and (2) During normal operations, they serve to pinpoint zones which require special intervention to restore skid resistance and smoothness, also taking into account in critical areas the problems of noise, which are gaining increasing attention here in Europe. These requirements have been spelled out in the technical tender specifications adopted for the IRI-ITALSTAT motorway network and include fines in cases of failure to respect these standards. In like manner, quality-control tests have been developed to assess the trend of skid resistance over time in composite materials taken from actual road pavements (passing the APA tests (Accelerated Polishing of Aggregates Using the British Wheel), which measure just the component materials).
The methodology already presented and proposed for the Italian motorway network, based on high-speed monitoring equipment such as the ARAN III, the longitudinal profile analyzer (APL), and the SUMMS (Survey Machine for Macrotexture and Skid, derived from the SCRIM), should ensure lasting, safe, and comfortable pavements obtained at optimal costs.