Condition assessment of critical infrastructure with GPR

Tunnels, bridges and dams represent some of the most critical public infrastructure. This paper presents case studies in novel application of GPR for condition assessments of these structures. The 200st Overpass in Langley, BC, Canada case study is a successful application of multiple frequency GPR systems to assess the structural condition of a critical highway overpass along the Trans Canada corridor. The GPR survey revealed construction deficiencies including mapping subsurface voids which was necessary in order to design proper remediation. The Mission, BC, Canada case study illustrates using Pipe Penetrating Radar (PPR), the underground, inpipe application of GPR for mapping voids outside a reinforced concrete storm sewer pipe. The same void was located and confirmed from an above ground GPR survey, thus successfully combining the results of in pipe, high frequency PPR with above ground low frequency GPR surveys. A 33 inch diameter vitrified clay pipe (VCP) that experienced catastrophic failures despite being installed only seven years ago in a California municipality was the subject of the third case study. PPR and CCTV inspection of over 9,000 ft of pipe provided quantitative pipe condition data and allowed the asset owners to design the most suitable and cost effective rehabilitation and replacement strategy.