HANOVER, NEW HAMPSHIRE – Fiber-optic cable is the backbone of the Information Age, delivering crucial services such as high-speed internet, telephone and cable TV into millions of homes and businesses.
But a team of scientists at the U.S. Army Engineer Research and Development Center’s Cold Regions Research and Engineering Laboratory (CRREL) in Hanover, New Hampshire, is putting fiber-optic cable to a much more unconventional use: determining the thickness – and therefore safety – of freshwater ice.
The CRREL researchers are pioneering a process called Distributed Acoustic Sensing (DAS) that turns a fiber-optic cable laid onto the ice surface into a vibration monitoring sensor. The team has dubbed the technology “DAS-Ice.”
“With DAS-Ice, we observe vibrations occurring every few feet along miles of cable which allows us to detect and localize a change in the vibration landscape,” said Dr. Meghan Quinn, a research geotechnical engineer at CRREL’s Remote Sensing/GIS Center of Expertise. “The vibrations along the cable change as ice thickens or thins, so by characterizing and monitoring those vibrations, we can obtain extraordinarily accurate measurements of ice thickness.”
‘Is the ice safe enough?’
If you’ve ever gingerly made your way across a frozen lake, you can understand how important it is to know with a good deal of certainty how thick the ice is. However, the standard way to measure ice thickness – simply auguring holes into the ice at various intervals and taking measurements – has several drawbacks.
“Ice can really vary in thickness and strength, and the time lapse between measurements using the auger and measure method can add a lot of uncertainty as well,” said Quinn. “Checking only a few spots may miss thinner areas of ice that are unsafe. Just because the ice is thick enough in one place, doesn’t necessarily mean it’s thick enough in another.”
And physically drilling holes in the ice to test its thickness isn’t always feasible when analyzing a large area or in extreme weather. The CRREL team has demonstrated that miles of DAS-Ice cable covering hundreds of acres can be deployed in a matter of hours.
“Let’s say we are talking about determining if the ice on a large freshwater lake in Alaska is thick enough to drive across,” Quinn suggested. “In theory, DAS-Ice could quickly be deployed across the area and then be able to constantly monitor conditions indefinitely.”
Once DAS-Ice is deployed, the data collected can be accessed remotely, meaning researchers (or outdoor recreation operators) can monitor ice conditions from the safety and comfort of their office or home.
“It’s not only going to be warmer and more convenient to collect that data, but safer too since you don’t have to send somebody out on the ice each time you want to assess the ice thickness,” said Quinn.
Using DAS-Ice to increase Situational Awareness
And while it’s easy to see the safety and recreational benefits offered by DAS-Ice, Dr. Quinn and her team are exploring several other intriguing ways to put the technology to use.
For example, says Quinn, when paired with acoustic signature profiles developed with the assistance of AI machine learning, DAS-Ice could greatly improve emergency response times or even help the U.S. military monitor vast expanses of terrain.
“Deploying DAS-Ice along ice roads would alert emergency response personnel to an ice breakthrough,” said Quinn. “Or it could detect the movements of potential adversaries by signaling the presence of vehicles.”
“I think we are only just starting to scratch the surface on all the ways this technology can be put to use. The opportunities are endless.”