Traffic Speed Deflectometer

Email : TSD@pavementanalysis.com


Conversion of dynamic TSD bowls to equivalent FWD static bowls: NZ Interpretation.pdf

This process is an effective substitute for a full dynamic analysis because it enables any of the traditional widely used FWD layered elastic models to be used directly by any user.

Note that after using the above spreadsheet all TSD files must first be validated for consistency in each specific environment/terrain by using layered elastic models as checks to ensure (i) there is no persistent bias between subgrade moduli obtained in adjacent (or opposing) lanes if the TSD field testing is done on different days, and (ii) that testing in a subsequent year confirms similar subgrade moduli in each lane. This is because the outer sensors are the most sensitive in the process of bowl determination and they are controlled primarily by the subgrade stiffness.

If encountering any issues with TSD-FWD conversion, or want a site-specific conversion and validation done, contact the Pavement Analysis Team here
(No service charge if it can be done with an existing model).

Publications relating to TSD can be found in the Publications Page.