For More Information

John Ragsdale
Research Specialist III
Pavement Management
Texas A&M Transportation Institute
1111 RELLIS Parkway
Bryan, TX 77807
Ph. (979) 317-2312 · Lab (979) 317-2266

The falling weight deflectometer (FWD) is a test system for performing non-destructive testing of pavements. The system develops force from acceleration caused by the arrest of a falling weight. These forces are transmitted onto the surface of a structure, causing it to deflect much as it would due to the weight of a passing wheel load.

Because the FWD is a complex system that contains electrical, hydraulic, and mechanical systems, proper calibration is needed to ensure accurate data are obtained. The Federal Highway Administration supports a Texas Department of Transportation managed calibration center (operated at TTI) that serves the southern region. The center calibrates the sensors on the FWD, ensuring proper data collection in the field.