Infrasense Performs Statewide Falling Weight Deflectometer (FWD) and Ground Penetrating Radar (GPR) Pavement Structure Evaluations in New Jersey

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Infrasense recently conducted Ground Penetrating Radar (GPR) and Falling Weight Deflectometer (FWD) testing along 14 highways located throughout New Jersey. The GPR and FWD data were analyzed to provide the client with pavement layer thicknesses, layer moduli, effective structural number (SN), and load transfer efficiency (LTE) values.

GPR Plot, Travel Lane Wheel-Paths

Infrasense recently conducted pavement structure evaluations of 14 highway sections in New Jersey. A vehicle-based Ground Penetrating Radar (GPR) survey yielded continuous pavement layer thickness data along prescribed offsets within the project sections. Falling Weight Deflectometer (FWD) testing was also performed at over 1400 locations along the project sections, which provided the data needed to calculate pavement layer moduli and effective structural number, as well as the load transfer efficiency (LTE) of the concrete slabs under the AC surface layer. Over 200 cores were available which aided the GPR analysis by confirming layer classifications and depth calculations. The results provided the client with valuable information to facilitate rehabilitation design efforts. Deliverables included tabular and graphical datasets with each point linked to precise GPS coordinates. These datasets help visualize how the constructed layers of the roadway change along the length of each lane.

The GPR data collection system was made up of a pair of 1 GHz air-launched horn antennas and a SIR-30 control unit, both manufactured by GSSI in Nashua, NH. The final report included a quantitative summary of average layer thicknesses in each lane, along with visual plots showing the sub-surface strata along the length of the section. The GPR pavement surveys are carried out according to ASTM D4748-10. The resulting data shows a cross-sectional slice of the pavement strata at various offsets. Each slice includes the surface, and any material change in the first few feet below the surface. The data is processed and analyzed using proprietary internally developed software specifically designed for pavement and bridge assessments.

The FWD equipment included a Dynatest Model 8200 trailer mounted system. Deflections were measured utilizing seven calibrated sensors spaced at specified offsets from the load cell. Testing was performed in accordance with ASTM D4694-09 (2020) and ASTM D4695-03 (2020) with load drops performed at a total of 1,400+ locations across the project sites. All test locations were documented in terms of linear distance using a DMI, and with GPS coordinates.

Over the past 12 months, Infrasense has completed pavement structure evaluations across over 3000 miles of roadways in Arizona, California, Canada, Georgia, Idaho, Illinois, Massachusetts, Montana, Maryland, New Hampshire, New Jersey, Rhode Island, South Carolina, Virginia, Vermont, and Wisconsin. Infrasense methods have addressed a variety of pavement structures including asphalt over granular base, composite pavements, continuously reinforce concrete pavements (CRCP), jointed plain concrete pavements (JPCP), and jointed reinforced concrete pavements (JRCP).

About Infrasense, Inc.
Since 1987, Infrasense, Inc. has applied advanced technologies to address the most difficult challenges in subsurface scanning. Infrasense's engineers nondestructively extract critical information from a diverse range of structures. In addition to providing ongoing subsurface evaluation services to clients across the country, the firm has also conducted numerous research programs to advance the field of subsurface detection and nondestructive evaluation. To learn more about Infrasense and the services we provide, visit our website:

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Ryan Grover
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