Remote Sensing for Bridge Scour

Pennsylvania has one of the largest number of bridges in the nation with over 22,000 bridges statewide [1]. Most of these bridges are over waterways. As a result these bridges are susceptible to bridge scour, the washing away of fill around structures, which compromises the safety of the bridge. Bridge inspections have a limited frequency at which they can occur. In between these inspections, events may happen that would indicate immediate action be taken. In some cases, the action necessary may be to shut down the bridge to protect the safety of travelers. Additionally, during floods, even if an inspection team is present at a bridge, their traditional means in acquiring data about the state of the bridge could be severely limited. In an effort to continually monitor the health of these bridges, state and federal departments of transportations are investigating different monitoring methods and instrumentation. Notwithstanding, the Pennsylvania Department of Transportation (PennDOT) needs a low cost monitoring solution to supplement their current monitoring infrastructure. Float out devices are an option that PennDOT has identified as a promising addition to their bridge scour monitoring capabilities. The float out device concept is to bury transmitters at various locations around a bridge structure which would eventually cause them to be released due to the scour's removal of material around the device. A receiver on the bridge would receive the transmission and perform an action. A float out device system would provide an initial indication of scour severity for further investigation. A prototype system using a float out device has been developed for use by PennDOT. This system uses commercial off the shelf (COTS) parts and conforms to the available installation and operations means of the department. The system has been tested in a laboratory setting emulating its target environment and has proven adept at performing its required tasks