Combined Technologies Make For Most Efficient Underground Asset Detector

It’s a fact: most of us need some tangible proof of quality before committing to something. This is especially true when this “it” is incredibly important and the commitment is costly. 

For the utility industry, this “it” is an underground asset detector. Detectors, which come in several forms, tend to be a bit pricy and the process of detecting buried assets can be quite time consuming.  So, utility professionals have every incentive to find the perfect tool, and to prove to the rest of the industry what “it” is. The search for this perfect tool recently led a group of scientists and researchers to conduct an experiment. The complete findings of this experiment are documented in a paper released by Auburn University  Geospatial Research and Applications Center, GRAC. Here’s the gist: 

Armed with  two of the most commonly used underground asset detectors—GPS,  and a magnetic locator, (and adding an RFID reader for verification of a buried asset point marker found before any digging)—the team, along with a group of research students, recently traveled to a waterside city in Alabama to put the tools to the test. Here in Gulf Shores, where layers of sand and debris often obscure underground assets after a storm, the researchers buried a controlled group of tags and sent out teams of students to find them.

Each student team had no previous experience with any of the tools and was given the same 15 minutes of instruction in tool use. The team was instructed to search the beach three times each for a period of 15 minutes. In their first search, students were to use only a GPS unit and a shovel to detect assets, in the second only a magnetic locator and RFID reader. For the final search, teams were told to use all three tools.  An observer carefully monitored each team and kept track of time with a stopwatch. The actual order of the tests was randomized. No team was able to observe a previous team’s location efforts.

The Results

The first two tests were very frustrating for all of the teams. The first test, using GPS got the students off to a good start, but only led them to the general area of the tag. They then had to take to digging in the sand hoping to catch a glimpse of it. The average time taken to accurately locate a buried target using only GPS and a shovel was 14.11 minutes. (There was lots of guessing about the accurate location and much unnecessary digging!)

In test 2, unaided by GPS, the magnetic locator and RFID reader were only somewhat better.  Since the magnetic locator works by detecting the magnetic field of the permanent magnet associated with the RFID tag, it has to be in close proximity to the tag to detect it. So in this test, students had no GPS or landmark clues and only a general idea (“over that way somewhere”) where to look. The RFID reader, of course, is useless without a tag to read.  The average time taken to locate and verify the Magnetic-RFID target was 10.47 minutes.  No digging was needed because the target was accurately (magnetically) located and verified by RFID.

Thankfully, the spirits of the students were raised in the final test.  When allowed to use all three tools, GPS, the magnetic locator, and the RFID reader combination, the students were able to find and verify the markers without digging. It was easy as 1-2-3!  The average location and verification time for a buried asset point was significantly reduced to an amazing 2.51 minutes!   

The reason these tools work so well together is that the synergy of each makes up for the other’s shortcomings. The GPS unit provides guidance, showing users where to focus their search, the magnetic locator provides the accurate location of the buried magnet, and the RFID tag gives verification and information about the asset point that the GPS cannot.

Where the first tests were disappointing at 19% and 39% asset point location success rates respectively, the final experiment resulted in 91% of the magnetic-RFID tags accurately found and verified in the 15 minute period. 

Not only that, the students enjoyed using the combination of tools, were much more positive during this final attempt and quite pleased with the results. As one student suggests, there’s no doubt about it: “The combination was dynamite!”