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A018 QUANTITATIVE INSPECTION OF SEWER SYSTEMS USING GEOPHYSICAL METHODS Abstract 1 To investigate the conditions of accessible underground sewer systems the geophysical methods seismics ground penetration radar (GPR) methods from borehole geophysics ultrasonic and impact-echo measurements as well as gravity geoelectrics electromagnetics and thermography had been applied in a 40 m long artificial underground test track in Gelsenkirchen (Germany). The test sewer track consists of different concrete pipes with diameters of 2.2 m and concrete thickness’ between 20 and 42 cm which are usually used in Germany. The goals of the test measurements were to find techniques which get more