Guardians of the Gateway: Meet Hennepin County’s Bridge Inspectors
Every day, thousands of cars drive across two bridges on Bass Lake Road built above Elm Creek in Maple Grove.
“These bridges are in really good shape still. They’re fairly new,” said Mark McLarty, Hennepin County’s lead bridge inspector.
But even a new bridge is susceptible to wear and tear.
“Well, gravity is the No. 1 enemy of a bridge,” said McLarty. “From the time they build it, they’re trying to fall down.”
So far this year, McLarty and his team have inspected 114 of Hennepin County’s 149 bridges. They look at each bridge at least once every two years.
“We really want to make sure that there’s no drastic changes every two years,” he said. “We’re looking for rust coming out of the concrete, we’re looking for rusting steel, we’re looking for bearings that aren’t moving anymore, things like that.”
The bridge inspection process is an involved one.
On a recent Thursday in early October, engineer Andrew Trombley was lowered down from Bass Lake Road in a machine called the “under bridge inspection vehicle.”
It’s his mission to look for signs of deterioration and fatigue.
Andrew Trombley, an engineer with Hennepin County, prepares to be lowered under a bridge along Bass Lake Road in Maple Grove.
“Right now, I’m looking at the bearing seat and the bearing pad to see if there’s any corrosion or rust or if it’s moved,” said Trombley, Hennepin County’s principal engineer technician.
It requires years of training for Trombley to observe and document the issues on the bridge with the naked eye.
“I believe it’s very important for the safety of the public, and for people, to get to and from work every day,” Trombley said, when asked about the importance of his work.
Some Hennepin County bridges can be inspected in a matter of hours, while others can take weeks.
Once a bridge starts to deteriorate, they inspect them more often.
“I think we can stay ahead of the replacement schedule this way,” said McLarty. “We can document the deterioration, start to see patterns. And as we see the pattern increase and how fast it’s deteriorated, we can schedule replacement. And budget-wise, that’ll really help too.”
As for the Maple Grove bridge on Bass Lake Road, the team determined that it’s still in good shape. Which means they’ll be back in 2027 to repeat this process once again.
“It feels pretty good at night to know that I can go to sleep and know that the bridges we looked at are gonna remain safe and don’t have to worry about them,” McLarty said.
Hennepin County engineers say that while they examine bridges every two years, issues can pop up between inspections. They ask people to report any problems they encounter on the county website.
Meanwhile, for detailed reports on the condition of every bridge in Minnesota, you can go to the Minnesota Department of Transportation website.
Hennepin County Engineer Andrew Trombley inspects a bridge in Maple Grove.
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