Investigation of underwater bridge inspection methods.

MSF SUGAR PTY LTD investigated the equipment and methods currently available for performing non-destructive underwater bridge inspections and their effectiveness in minimising the risk to personnel performing inspections. Two commonly used methods in marine industry (Remotely Operated Vehicle ? ROV and Sonar) were trialled and reviewed with the assessment of outcomes initiating the trial of a third option, which was a Pole Mounted Camera (PMC). All methods proved effective in removing personnel from many of the risks associated with entering the watercourse to perform inspections. Available sonar technology demonstrated strong capabilities in areas of surveying the surrounding environment, however was limited in the areas of detail and detection of finer surface defects. ROV technology proved the most effective in eliminating the requirement for bridge access and proved versatile and effective in performing inspections; however this method had challenges around accurate navigation, entanglement in debris, disturbance of silt deposits and strong currents. Pole mounted cameras demonstrated high effectiveness in shallow streams where physical access for the worker and extension pole was possible, allowing for a broad coverage and initial inspection. However, it was limited by depth and manoeuvrability. Due to the large variation in environmental conditions, the best method of approaching an inspection was knowing the strengths and weaknesses of trialled methods in order to maximise the effectiveness of the underwater inspection