EVALUATION OF PANEL RATING METHODS FOR ASSESSING PAVEMENT RIDE QUALITY

The results of a pilot study that attempted to determine the preferred psycho-physical scaling method for obtaining panel ratings of pavement ride quality are reported. Five principal tasks were undertaken: site selection, scale selection, panel selection, design and conduct of the experiment, and analysis and interpretation of the results. Thirty-three flexible road sections covering a wide range of roughness (uniform within each site) were selected, and a 92-mile route that could be traversed, at normal operating speeds, in 3.5 hr was established. Three candidate scales were selected for evaluation: the original AASHO rating scale, a scale developed by Holbrook that uses precisely defined and positioned word cues, and a nonsegmented scale with word cues only at the end points. Fifty-four average drivers were divided to (a) determine which scaling method resulted in the greatest agreement between raters and (b) determine which of the three scaling methods resulted in the best correlation between subjective and objective measures of road roughness. The results indicated that either subjective scale, if carefully used (i.e., with exact instructions and precise control of conditions), can provide high agreement between raters and exceptionally high R squared values. (Author)