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Illustration. Image of the falling weight deflectometer (FWD) equipment. Arrows show the drop weights, loading plate, and deflection sensors.

Falling Weight Deflectometer (FWD)

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. FHWA supports a TxDOT managed (operated at TTI) calibration center that serves the southern region. The center calibrates all the sensors on the FWD, ensuring proper data collection in the field.

For More Information

John Ragsdale
CE/TTI Building, Room 503
TTI/Flexible Pavements
Texas A&M University System
3135 TAMU
College Station, TX  77843-3135
ph. (979) 845-9921 · fax (979) 845-1701
J-ragsdale@tamu.edu

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