Quick fix for failing bridge

A 30-year-old bridge on Shady Lane in Evergreen is being targeted for fast-track repairs this year because of its failing deck, according to the Montana Department of Transportation.

The steel-reinforced concrete bridge spans a creek just south of Montana 35.

Earlier this month, drivers reported that an 18-inch-wide by 4-foot-long hole had opened in the southbound lane along a joint in the bridge’s deck.

Maintenance workers quickly covered the hole with a thick steel plate pinned in place, Missoula District Administrator Ed Toavs said. That leaves the bridge open for the estimated 5,300 drivers who use it each day— but the span needs more substantial repairs.

“We had a bridge maintenance engineer come look at it just to make sure it’s safe,” Toavs said. “It’s in good shape, but something we’re keeping a close eye on and we want to expedite repairs.”

Repair options are being explored.

Dwane Kailey, engineering division administrator for Montana Department of Transportation, determined the Shady Lane Bridge has serious deck issues.

He issued an “exigency declaration” for the structure on March 13.

That lets the department pursue fast-track repairs and expedite some of its normal project design and delivery procedures.

“The deck is failing along the joints connecting the individual beams. Maintenance has placed a steel plate over a recent hole. Additional holes may occur at any time,” Kailey wrote in the declaration.

“Given the accelerated decay of the deck, this structure is in need of immediate repair,” Kailey continued. “Our goal is to complete this rehabilitation work quickly and no later than the end of this construction season.”

Flathead County built the Shady Lane Bridge in the early 1980s and later turned maintenance responsibility for both it and the paved secondary road over to the Montana Department of Transportation, as mandated by the Legislature.

With a normal bridge with a poured slab deck, the department would pursue spot deck repairs or a partial or full deck replacement as needed, Toavs said.

But the Shady Lane Bridge’s integrated design complicates the search for an effective fix. Multiple bulb tees span the length of the bridge and “bulb out” at the top to join and form the deck.

While the most significant deterioration is centered along those joints in the bridge’s deck, some cracking and deterioration may extend down and into those precast concrete beams.

“In this case, where the bulb-tees are the superstructure and the deck, it gets more complicated,” Toavs said. “We’ll be meeting internally this week or next with our bridge folks to decide on a course of action, as far as do we replace those bulb-tee beams or pursue another configuration.”

Reporter Tom Lotshaw may be reached at 758-4483 or by email at tlotshaw@dailyinterlake.com.