Developing a Testing Device for Total Pavements Acceptance—Final Report

During the fourth year of Project 0-6005, construction of the Total Pavement Acceptance Device (TPAD) was completed. The TPAD is a multi-function pavement evaluation device used to profile continuously along pavements at speeds in the range of 2 to 5 mph. The test functions include those associated with a Rolling Dynamic Deflectometer (RDD), ground penetrating radar (GPR), Distance Measurement Instrument (DMI), high-precision differential Global Positioning System (GPS), surface temperature and digital video imaging of the pavement, and right-of-way conditions. The towing frame system used to position and pull the RDD rolling sensors was developed and installed on the TPAD. The towing frame system minimizes the transmission of vibrations from the TPAD mobile platform and loading system to the rolling sensors, and allows for the incorporation of three rolling sensors (front, center, and rear) on the TPAD. The front and rear rolling sensors have 12.5-in. diameter wheels and a 90-lb hold-down weight while the center rolling sensor has 9.5-in. diameter wheels and a 40-lb hold-down weight. Initial deflection measurements using the new towing frame/sensor cart arrangement were performed at the Texas Department of Transportation (TxDOT) Flight Services Facility (FSF). Based on these tests, it is recommended that most deflection profiling be done with the center and rear rolling sensors at a testing speed of 2 mph. Three case studies with the TPAD were performed at a testing speed of 2 mph: on US 297 near Wichita Falls, at TxDOT FSF, on US 290 near Houston. The pavements at the three sites are continuously reinforced concrete pavement (CRCP), jointed concrete pavement (JCP), and full-depth, hot-mix asphalt (HMA), respectively. The TPAD proved durable during the testing period and provided valuable information for all three types of pavements.