Macrotexture Assessments Using Line-Laser Technology

Abstract

The Florida Department of Transportation (FDOT) State Materials Office measures statewide macrotexture in relation to mean profile depth (MPD). This is done using point-laser systems mounted along the driver-side wheel path of friction evaluation vehicles. Historically, point-lasers have been recognized by the FDOT to accurately measure MPD on flexible pavement. However, current point-laser technology is unable to measure the anisotropic texturing of rigid pavement, such as longitudinal diamond ground (LDG) concrete. For this reason, the FDOT purchased two LMI Technologies Gocator-2342-3B-12 line-laser systems, which have the capability of measuring longitudinal texture. As received, internal testing conducted by the FDOT had shown poor agreement between line-laser MPD and accepted reference values on both flexible and rigid pavement. Since then, a research-based approach in configuring the line-laser system to accurately assess pavement macrotexture has been completed. Results from the statewide testing showed that the updated line-laser system produced MPD values on flexible pavement with an average difference of ±5.2% when compared with the point-laser system. On rigid pavement, the updated line-laser system produced MPD values with an average difference of ±10.4% when compared with those produced by a circular track meter. Precision testing showed that the line-laser system produced repeatable results on all pavement types with an average repeatability limit, r, of 0.25 mm and reproducibility limit, R, of 0.30 mm, which was comparable to the precision results of the point-laser system.