For the last ten years an annual correlation trial for Falling Weight Deflectometers (FWDs) has been held in the UK. The objective of the trial is to assess the performance of all FWDs (including Heavy Weight Deflectometers, (HWDs) and Super Heavy Weight Deflectometers (SHWDs)) operating on the Highways Agency (HA) strategic road network. The performance of individual machines is assessed by examining and monitoring the results from the machines operating on specified test sections of the TRL Small Roads System (SRS). Only machines that can demonstrate satisfactory performance in the correlation trial are subsequently approved for use on the HA strategic road network.
This report describes the conduct and findings of the 2009 correlation trial and presents the details of the machines that are approved for use on the HA strategic road network in 2009/2010.

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