Given the aging condition of much of the nation’s navigation infrastructure, managers need accurate and real-time information on the conditions of such structures as locks, dams and bridges operating well beyond their expected design lives.
Inspecting these critical components can be expensive, time consuming and dangerous. However, the cost of doing nothing is much greater – as an easily repairable glitch can grow much larger if left unchecked, causing a catastrophic failure that closes key navigation routes, severely snarls supply chains and inflicts millions of dollars in economic losses.
The U.S. Army Corps of Engineers (USACE) is solving this challenge through a broad range of structural health monitoring (SHM) capabilities. It has developed sensors that serve as virtual eyes and ears, providing constant, real-time information on structural conditions. SHM can warn of impending failure and provide an estimate of the remaining life and reliability of an infrastructure component or system.
Leading this research is Dr. Brian Eick, a research civil engineer with the U.S. Army Engineer Research and Development Center’s (ERDC) Construction Engineering Research Laboratory and the technical lead and program manager of ERDC’s Structural Health Monitoring Program.
“[SHM] provides a clear line of sight from observation to deciding a plan of action,” Eick said. “We use sensors on the infrastructure to continuously and in real-time collect information about the health of the infrastructure that can then be used to make decisions.”
This effort paid large dividends in September 2009 when engineers monitoring senor data at The Dalles Lock and Dam on the Columbia River noticed large and unusual shifts involving one of the lock’s steel girders. Further investigation by a dive team discovered extensive cracking on the lower section of the gate. Authorities quickly initiated emergency repairs, preventing more significant damage that could have closed the lock for months or even years.
Today, Eick and his team are seeking new ways to make SHM faster, more dynamic, and as accurate as possible.
“It is very difficult to access some of these structures routinely and safely,” Eick said. “So, we ask how do we put sensors on it or do we even need to put sensors on certain pieces to collect data? One of the latest things we have been doing in research and development is non-contact sensing, using cameras or lasers to obtain the same information you would otherwise need to put a sensor on the structure to collect.”
Developing no-contact sensing capabilities negates the need to place sensors on structures, run cables and even the worry about the need for batteries, which is a challenge, particularly on those infrastructure components that are very remote.
There are many other areas of SHM under development, including new algorithms to process collected data, methods to remove environmental noise that may cloud this data, and approaches to interpret changing weather conditions that corrupt the data.
Looking ahead, SHM development will include the use of digital twins to help managers make decisions and ensure maintenance investments are optimized.
Eick said digital twins -- which are digital replicas of physical assets, processes, people, places, systems and devices -- will streamline data processing and analysis required for operation and maintenance and provide a centralized platform for modeling scenarios that will better prepare and inform decision makers.
“Where I see USACE going soon is this notion like digital twins, where we have no contact sensing,” Eick said. “This is where we are focusing a lot of our efforts – how do we collect data without ever touching the structure?
“This is taking many different forms right now, such as cameras on robotic platforms, lasers, cameras and even UAVs.”
Given USACE’s mission to operate much of our nation’s waterway infrastructure, it must develop techniques and technologies that allow it to maintain those systems faster, better and at a lower cost. One of the focus areas of USACE’s R&D strategy is to modernize infrastructure and revolutionize the way those systems are operated. SHM is helping it do that.