Abstract
This report contains the findings of a study that produced recommended guidelines for measuring a longitudinal pavement profile to use in computing that pavement's International Roughness Index (IRI) and/or Ride Number (RN). The resulting guidelines are based on the determination of factors that affect roughness measurements, the quantification of the effect of these factors on repeatability and accuracy, and the determination of how and when these factors can be controlled. The research also sought to explain the underlying causes of common profile measurement problems to assist agencies charged with measuring longitudinal profiles in maximising the quality of their pavement management system's roughness estimates. (A)