Scour Monitoring Technology Implementation

Abstract

Bridge scour is the removal of sediment around bridge foundations and can result in the failure of the bridge. Scour monitoring is performed to identify unacceptable scour on bridges considered to be scour critical and determine when scour reaches elevations that could cause potential bridge failure. Two types of monitoring are available: portable monitoring and fixed monitoring. Prior to this project, MnDOT was only using portable monitoring devices, which requires the deployment of personnel to make physical measurements of scour depths. For some scour critical bridges, especially during high-water events, fixed instrumentation capable of continuous scour monitoring was preferred, but MnDOT lacked the experience or expertise to install this type of equipment. This project installed fixed monitoring equipment at two bridge sites and monitored them for three years to determine the effectiveness and reliability of fixed scour monitoring deployments. Several device options were installed to allow MnDOT to analyze the installation and performance of different types of sensors. Both systems operated for the three years with some outages due to various causes but overall performance was acceptable. The outages were mostly related to power issues and communication issues. Valuable lessons were learned through the deployment, which may be applied to future installations. The deployment executed in this project has provided the confidence to deploy other fixed scour monitoring equipment at key bridges around the state of Minnesota. In addition, the data collected during deployment of the scour monitoring equipment has been stored and provides insight into scour processes. This data can be used by other research groups for design or research purposes.