Minnesota nears end of 3,875 rush bridge inspections

LAKEVILLE, Minn.  — In near-zero weather and with 70 mph traffic whizzing past above, a team of inspectors touches, taps and tugs at concrete on a Minnesota freeway bridge.

They're looking and listening for imperfections — part of a full-scale review of Minnesota bridges after the summer's deadly Interstate 35W collapse. Inspections of every river crossing, highway overpass and railroad bridge under state authority and many under local control should be done by Christmas.

Inspectors spotted flaws in at least 15 bridges that demanded immediate attention, and each has been quickly repaired or closed. Even as Minnesota has tended to its immediate needs, though, questions remain about the state's long-term funding for bridge maintenance and repair.

After the Minneapolis bridge collapse in August, governors and transportation heads nationwide ordered reviews of their states' bridges and inspection programs. A few states responded with expensive proposals for bridge safety.

In Maine, a report to the governor recommends boosting bridge spending by at least $50 million and increasing the pace of bridge replacements from 14 per year to 30 or 40 per year. In New Jersey, the highway department plans to commit an extra $150 million annually to repairing structurally deficient bridges even if means less for other road projects.

"There's been a big shift in where we are putting money," said Brian Strizki, New Jersey's chief transportation engineer.

Minnesota Department of Transportation officials said they expect next year's bridge maintenance expenses to be comparable to the $9 million spent this year. Spokeswoman Lucy Kender said some other bridge projects will be paid for through general accounts, but she couldn't give an amount.

Since August, nearly all of the 3,875 Minnesota bridges owned by the state have been examined by agency inspectors or private engineers hired under a $6.6 million no-bid contract. In a typical year, about half the bridges get inspected.

The precise cause of the bridge collapse responsible for 13 deaths is still unknown. MnDOT's aim with the rapid inspections was to assure their structural integrity and restore public confidence, said Duane Hill, the engineer overseeing the project.

The Associated Press reviewed thousands of summary pages from those inspections. Crews documented cracks in columns, separation between concrete and rebar, leaking joints, loose nuts, cracked welds, peeling paint, rusty rails and overgrown trees.

Relatively few contained "critical findings," where corrosion, cracking or weakness in key parts could cause an entire bridge to fail.

In northwestern Minnesota, a bridge over the Red River was shut down for four days until a crack in a support bracket got fixed. Serious defects in timber parts prompted closures in a few southern Minnesota bridges. To reopen, Hill said the critical findings had to be addressed, some by reducing the weight limits for trucks.

"When we inspect a bridge and it stays open, it's safe," Hill said.

State legislators have intensely scrutinized agency practices since the bridge fell. Rep. Bernie Lieder, chairman of a transportation finance committee, said there will be an expectation for action now that the agency knows what plagues each bridge.

"There's going to be a little pressure on them to make darn sure that things get repaired," said Lieder, a Democrat from Crookston and a former county highway engineer.

The inspection process can be tedious and involves basic tools.

Along Interstate 35 this week, a crew from the engineering firm PB Americas Inc. trudged beneath a pair of freeway bridges that cross a small lake. They circled the bridges' concrete footings, measured the length and width of cracks and snapped photos. One inspector recorded his findings on a clipboard; another tapped sections with a hammer to listen for hollowed spots, then wiggled the claw end in cracks to see how loose they were.

Bridges deemed fracture critical — a rating given to the Interstate 35W bridge due to a lack of structural backup mechanisms — get the hands-on treatment and most also get ultrasonic testing that can reveal cracks inside pins or girders.

The advanced testing detected a 3/32-inch gouge in a vital component of a single-lane bridge in Redwood County — a defect county highway engineer Ernie Fiala said his own inspectors weren't equipped to find. The bridge over the Minnesota River in western Minnesota was closed for several weeks and reopened with new weight restrictions. Additional testing will be done in a few months.

Just this week, Fiala ordered his first permanent closure of a bridge in his 10 years as lead engineer. Timber supports on a bridge crossing a stream in Vail Township have deteriorated beyond repair, he said.

"There's not much holding it up," he said. "We're not taking any chances."

In nearby Lyon County, Public Works Director Anita Benson heard grumbling when she decided to close some ailing bridges under her watch as a last resort when weight limits were being ignored.

"You don't do that lightly, but on the other hand you don't let the public cross a bridge that is unsafe either," Benson said. "Bottom line, Lyon County chooses public safety over public inconvenience any time."