The Benkelman beam has been one of the most commonly used methods of measuring surface deflections of a highway pavement. A Benkelman beam is based on a simple lever-arm principle and uses dial guages to measure surface deflection under an applied load. In 1971, the Commonwealth of Kentucky purchased a Road Rater for use by the Department of Transportation, Division of Research. The Road Rater applies a sinusoidal force to the pavement at a fixed frequency; surface wave velocities are measured and electronically integrated to obtain surface deflections, Since 1971, work has progressed toward the development of a pavement evaluation methodology using Road Rater deflections. Analyses presented in this report will illustrate some relationships between the Benkelman beam and Road Rater deflections. Theoretical and field measured deflections are considered.

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No. 523

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The contents of this report reflect the views of the authors who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Bureau of Highways nor of the Federal Highway Administration. This report does not constitute a standard, specification, or regulation.