3D ground penetrating radar assessment of the Tay Road Bridge

Overview

The focus of the event will be on the findings of a 3D Ground Penetrating Radar(GPR)  survey and its use to detect the thickness of the asphalt, the positions of the rebars within the concrete deck and to identify any anomalies within the bridge deck. 
 

The Tay Road Bridge is 2250m in length and spans the river Tay between Dundee and Newport-on-Tay. The bridge was designed by William A Fairhurst and took three years to build between 1963 and 1966 at a cost of £4.8m. In 2020, WSP were commissioned by Tay Road Bridge Joint Board to undertake a pavement surfacing investigation to develop a maintenance strategy. The pavement surfacing on the bridge is a fully flexible construction and is approximately 55 years old and has not required any major maintenance since its construction.  Surveys were carried out in lanes 1 and 2 along the northbound and southbound carriageways. The pavement investigation included a Digital video survey, 3D Ground Penetrating Radar (GPR) survey, profilometer survey, road cores of the surfacing and laboratory analysis of the material.

 The GPR survey used a step-frequency ultra-wideband ground coupled and an air-coupled antennae manufactured by 3D-Radar. All data was positioned using Real Time Kinetic (RTK) GPS and was transformed into an Ordinance Survey Grid to enable an accurate 3D model of the bridge to be created of the GPR data. This presentation highlights some of the remarkable findings from the analysis of this 3D GPR model of the bridge deck.