When looking at the accuracy of profilometers, most agencies are mainly concerned with hardware precision rather than the errors caused by the human operators or environmental factors. The Wyoming Transportation Department and the University of Wyoming conducted a joint research project to determine the effect of these two factors on the accuracy and repeatability of roughness and rut depth measurements. The Wyoming Transportation Department's road profiler, which is a duplicate of the South Dakota road profiler, was used in this study. A total of 36 test sections were tested by three different operators to determine the effect of human factors on measurement repeatability. In addition, a concrete test section was monitored and tested several times in the 1991 testing season to examine the effect of various combinations of environmental factors on the measured roughness. The data collected were then tabulated and statistically analyzed. The design of the experiment is summarized, the data that were collected are described, and specific conclusions with regard to the effect of human and environmental factors on the accuracy of roughness and rut depth measurements are discussed.