Radar testing of masonry arch bridges with soil backfill

This paper focuses on the use of single and 2-channel digital radar systems to investigate masonry arch bridges with soil backfill using antennae in monostatic, bistatic and transmission mode, also for tomographic inversion. From a laboratory study it has been demonstrated that even small concentrations of sodium chloride salt can cause substantial attenuation of the signal. Thus routine de-icing using salt can cause significant problems for the use of radar for the investigation of masonry arch bridges. In addition, bridges having a higher moisture content will also be subject to substantial signal attenuation. Fields studies are given on two bridges in Scotland to illustrate the applicability of the various radar techniques using a multi channel digital radar system.