Comparison of Road Profilers

Abstract

Devices available to measure road profiles vary from the hand-held Dipstick to high-speed, vehicle-based profilers. High-speed, vehicle-based profilers generally use an ultrasonic, laser, or optical measuring system. A profiler calibration study was conducted by the road profiler user group in 1994 by establishing regional calibration centers in Mississippi, Nevada, Pennsylvania, and South Dakota. The study compared the data collected by the profilers with the Dipstick data, and analyzed the effect of surface texture on data collection. At each regional calibration center, asphalt concrete and portland cement concrete test sections were established. Thirty-eight road profilers belonging to state agencies, equipment manufacturers, and FHWA participated in the calibration study. Dipstick measurements and sand-patch tests were conducted at all test sites. The International Roughness Index (IRI) was used as the parameter for performing the analyses. The results of the analyses for the sites in Pennsylvania and South Dakota are presented. The agreement between Dipstick IRI and profiler IRI for a specific profiler varied from site to site. For a specific profiler at some sites, the agreement with the Dipstick IRI was good, while at other sites the agreement was poor. The profilers with ultrasonic measuring systems generally had poor agreement with Dipstick IRI values for asphalt-surfaced sites that had aggregate seal coats.