The objective of this paper is to report on the results of an experiment that evaluated the effects of vehicle size, vehicle speed, residence of the rating panel, and training of the rating panel on the subjective evaluation of road roughness.
Five panels of 21 persons each were employed for the ratings, as were 34 road sections in Pennsylvania and 31 road sections in Florida. Both groups of road sections spanned a wide range of roughnesses. Two different types of vehicle were used in Pennsylvania, and a subset of the Pennsylvania road sections was evaluated at two different speeds.
The results of the panel ratings indicate that there was no significant effect of vehicle size for, the two sizes tested, or of vehicle speed on the subjective evaluation of road roughness, and that trained raters (i.e., experts) evaluated roads with the same rating as untrained raters (i.e., laymen). A small but significant effect of panel residence was found.
The implications of these findings are that vehicle size and (normal) vehicle speeds probably do not influence the subjective rating of road roughness and can probably be ignored in such panel studies, that experts can be used instead of laymen by states to perform subjective ratings, but that drivers from different regions of the country have different expectations regarding road roughness and this factor should be considered in such studies of road roughness.