Profile Equipment Evaluation (1378-2)

The Texas Department of Transportation (TxDOT) is implementing smoothness specifications based on profilograph testing as part of its construction quality control/quality assurance (QC/QA) program. Most tests are presently conducted using automated, California-type profilographs in which the equipment is pushed over a prescribed wheelpath. It appears that smoothness specifications will continue to be based on the profilograph, at least for the short term. However, in view of advances in profiling technology, it becomes prudent to investigate other methods of measuring surface profile and develop smoothness specifications based on profilers that offer greater accuracy and higher production rates. Already, a number of districts have expressed concerns about the sensitivity of the profilograph to short wavelengths or high frequency ripples. This observation demonstrates the need for more accurate measurements of surface profile for the purpose of building pavements that offer excellent ride quality, lower road user costs, and longer service lives. In pursuit of its goal of providing smooth pavements, TxDOT initiated a research project with the Texas Transportation Institute (TTI) to develop a smoothness specification for asphalt concrete overlays based on the new generation of pavement profilers that offer greater accuracy in profile measurement relative to the profilographs presently used in construction projects. Among other things, this research project evaluated a number of profile measuring devices to establish the availability of equipment for implementing a new profile-based smoothness specification in Texas. This report presents the findings of the profile equipment evaluation.