Bridge over troubled waters

A new technology for detecting and monitoring bridge scour is being jointly evaluated and developed by the US Army and Campbell Scientific.

The Montana State University TechLink Centre and the US Army Corps of Engineers’ Office of Research and Technology Applications, brought the parties together with the US Army Engineer Research and Development Centre – Cold Regions Research and Engineering Laboratory (CRREL).

The aim of the collaboration is to jointly evaluate software for determining bridge scour, a high-water threat to bridges.

Bridge scour is said to occur when sediments around bridge piers are washed away by water flow, particularly during high water events. The loss of sediments can weaken the bridge’s foundation and ultimately cause its failure. At least 17 deaths have been attributed to bridge failures since 1985 in the US alone.

The purpose of the current project is to develop an algorithm for analysing waveforms to automatically measure the scour depth. This algorithm would be used in an automated TDR (time domain reflectometry) bridge scour monitoring system.

The scour monitoring system that CRREL developed uses a TDR unit with a series of probes. The probes are imbedded in the stream bottom to measure changes in the sediment level around the submerged portion of a bridge. The system is believed to be highly accurate and can be developed to provide real time data during a high water event from the safety of a remote location.

Of the 482,000 bridges over waterways in the US, the Federal Highway Administration estimates that roughly 1 in 20 are scour critical. One in five bridges have foundations of unknown depth, making it difficult to determine their scour status.

The device is one of several new technologies under development for the purpose of monitoring scour-critical bridges.