LITTLE ROCK, Ark. – One year ago, crews discovered a major crack in the Interstate 40 bridge, closing the link between Arkansas and Tennessee for months.
The crack went unnoticed for years, forcing the Arkansas Department of Transportation to find the fractures within its inspection system. Now, ARDOT is utilizing new technology to change the standard for bridge safety.
Thousands of cars, trucks and semis pass over the I-40 bridge between Arkansas and Tennessee every day, but on Tuesday, May 11, 2021, those wheels came to a screeching halt when a group called into work on the bridge noticed a critical fracture, one that was missed for years.
“It’s like many events that affect your life,” ARDOT assistant chief engineer for operations Steve Frisbee said. “You’ll probably never forget it.”
Frisbee said he’s seen his fair share of emergencies in his more-than-20-year career – “bridges hit, bridges damaged, bridges caught on fire,” – but he said the discovery last year stood out because “we knew the enormity of this bridge.”
Even one year later, he still wonders what could have happened if it wasn’t caught that day.
“We still really don’t know,” Frisbee said. “It could’ve literally stayed there for months or years or it could’ve failed immediately.”
That near-disaster exposed the crack in ARDOT’s inspection system, leaving Frisbee and others with the same question – how did damage this extreme get overlooked for so many years?
That question led to a complete restructuring of the program, policies and training.
“When you have one weak link on such a serious thing, you’ve got to be prepared to have fallback plans,” Frisbee said.
One of those fallback plans is getting extra eyes in the sky.
“It was drone footage that could verify how long that crack was there,” Frisbee said.
ARDOT heavy bridge maintenance engineer Kevin Weston bought his first drone two years ago to see just how it could help the inspection process.
“I had in my mind that this could be a five-to-10-year goal bringing drones to the bridge inspection,” Weston said.
The I-40 bridge crack accelerated that timeline.
“We’ve implemented drones on the largest scale-out of any DOT within bridge inspections,” Weston said, noting that ARDOT now has 14 total drones that are being used in every district in the state.
The larger drone being used by crews for specialized inspections has a camera than can zoom in 200 times and high wind resistance. The smaller ones have obstacle avoidance sensors and don’t need GPS to fly, even providing to be nimble enough to “get into tight girder spacing.”
While out in the field, inspectors are looking for anything out of the ordinary.
“Shiny metal would mean fresh cracks, but anything that is rusted would appear that reddish brownish color, so that means you have a crack there that’s been rusting,” Weston explained. “So, you’d want to look for anything like that. You’d want to look for loose bolts of course.”
The changes don’t stop when the drones land. Once crews finish the inspection out on the bridge, Weston said they take that video to the office to review on larger monitors. The engineer said all of these efforts are to ensure that nothing goes unnoticed.
“Taking all your notes, putting it in your bridge inspection report, and part of that is if you see anything in that video, (then saying0 ‘Alright, let’s go back out and let’s confirm something,’” Weston said.
He believes this is just the beginning of ARDOT’s drone program, with new technology bridging the gap between an almost catastrophe and the future of bridge safety.
“I envision one day that every bridge inspector will have a drone in their truck like they have a hammer or ladder or binoculars,” Weston said.