A Truck-Mounted Scour Inspection System for INDOT

Scour monitoring may be a useful tool for the Indiana Department of Transportation (INDOT) in dealing with local scour problems at bridge sites, and a truck-mounted scour-monitoring system is an attractive option offering flexibility in deployment and cost-effectiveness. This report deals with two aspects related to the further development of such a system: i) a web application that combines the latest available information regarding streamflow with relevant information regarding bridges considered susceptible to bridge scour, thereby assisting in truck-deployment decisions, and ii) development of an acoustic positioning system as a replacement of the original mechanical positioning in order to improve the ease of use.The web application, written in Macromedia (now Adobe) Flash 7, provides a graphical (map) display of stream gaging sites and bridges, and the relevant information. The report discusses briefly its use and the software implementation.The acoustic positioning system is based on acoustically measuring distances from transmitters attached to the scour sonar housing to an array of receivers of known fixed positions, and is intended for use in determining reproducibly the position being probed by a scour sonar. Laboratory tests were performed with the system in isolation, and results were compared with locations determined from a Total station. It was found that, under relatively ideal laboratory conditions, the system could locate the transmitters within 1-ft in the horizontal and 1-ft in the vertical. For the more demanding location of a probed point on a hypothetical streambed, the system errors often exceeded this specification. Field tests, undertaken for both stationary-truck and moving-truck applications, but with the positions of transmitters nominally fixed with respect to the receivers, showed that the results were noisier, but appropriate pre-screening and post-processing yielded useful data.