Developing a Testing Device for Total Pavements Acceptance

What’s the Problem?

Destructive testing new and existing pavements is a pain-staking process that often requires boring holes, or coring, a pavement. No matter how many core samples are taken, each is indicative of the conditions at that particular spot. Non-destructive pavement deflection testing has been around for about 16 years. Rolling Dynamic Deflectometers (RDD) were developed by the Texas Department of Transportation’s (TxDOT) research program. There wasn’t an efficient way to continuously determine a road’s overall condition. To effectively analyze road failures, a comprehensive device that simultaneously collected data from multiple non-destructive testing methods was required.

What’s the Solution?

The TPAD, or Total Pavements Acceptance Device, is a highly modified geological surveying “thumper” truck designed for seismic testing. For the first time ever, the TPAD combines RDD with ground penetrating radar (GPR). These two technologies are coupled with video cameras and global positioning equipment. Combining these non-destructive testing methods into a single machine produces maintenance and rehabilitation data that is far more comprehensive and useful and either device can separately. TPAD technology was developed by TTI and the Center for Transportation Research at the University of Texas at Austin.

How Does the TPAD Work?

Operators drive the TPAD along a section of highway at 2-to-3 miles per hour. RDD and GPR data are recorded along with video information and global positioning coordinates. If any questionable areas are spotted during data analysis, the video can be accessed to see if there is anything visible on the surface. Additionally, the global positioning system marks each location with extreme accuracy. If a road crew needs to visit the site to access it in person, they know exactly where to look.

Benefits

TPAD technology has opened a new door in road surface maintenance and rehabilitation. Engineers are now able to thoroughly evaluate the structure of a road and recommend short term and long-term maintenance to prolong its life. Joe Leidy, a Pavement Structural Engineer for the TxDOT Austin District, is a TPAD advocate. “Ultimately, we should see a savings of taxpayer dollars by making better decisions with our rehabilitation strategies,” he said.