The International Roughness Index (IRI) is a widely used, internationally recognized index of roadway surface roughness. This TAC study was commissioned to develop practices to standardize collection, reporting and use of IRI data in Canada. The scope of the study was limited to the use of IRI on rural roadway applications (recognizing that urban conditions will be encountered in some instances), and on flexible (asphalt concrete) pavements systems which comprise virtually all rural highway infrastructure in Canada.

The study focused on identifying: The "State-of-the Technology" as it relates to data collection hardware, data collection methodology and practices, and software and processing that will provide an IRI value from a roadway longitudinal profile measurement, and The "State-of-the-Practice" as it relates to how the processed IRI data are stored, assembled, interpreted and used by transportation agencies.

A survey to obtain and update the practices of Canadian, US and International jurisdictions that use or are in the process of implementing IRI for network, project and construction smoothness QC/CA purposes was carried out. A survey of manufacturers of intertial profiler systems to solicit detailed electrical, technical and operational information was also undertaken. This study has resulted in the development of the "Best Practices Guidelines" that will standardize the measurement, calibration and verification of roadway longitudinal profile data collected using high-speed laser-based profilers, and profile analysis and IRI reporting procedures.