I-90 bridge project over Blackfoot River begins with new construction, pier removal

When completed, the old bridge piers in the middle of the Blackfoot River will be gone, and a pathway crossing under the bridge on the west end will add to a growing network of trails planned for the area. (Martin Kidston/Missoula Current)

A $15 million project to remove and reconstruct two aging bridges over the Blackfoot River on Interstate 90 is underway, though it’s expected to take two years to complete.

When completed, the old bridge piers in the middle of the Blackfoot River will be gone, and a pathway crossing under the bridge on the west end will add to a growing network of trails planned for the area.

“The plan, for this season, is to demo the existing bridge and build a new structure in its place,” said Ed Toavs, Missoula district administrator with the Montana Department of Transportation. “The new structure will have piers and and abutments that won’t be in the channel. It’s not advantageous to have those piers in the channel.”

The old piers served as a dangerous obstacle for river users, often prompting state officials to close that stretch of river during certain points of the year out of safety concerns.

The new structure will span the 230-foot distance and leave the channel unfettered. During construction, however, portions of the river will be subject to intermittent closures. Traffic on I-90 will also be diverted.

“If their schedule goes well and the weather cooperates, they want the new structure done by the end of this year,” Toavs said. “Next year, they’ll swap traffic and do the other bridge.”

The entire project is scheduled for completion in 2019, though cleanup may linger into the following season. The project was awarded to Frontier West and Morrison-Maierle and represents roughly $90 million in state transportation projects taking place in the Missoula Valley this season.

That more than doubles what’s typically under contract for a single season, Toavs said.

“If you get a year in the Missoula Valley that’s approaching $40 million to $50 million, that’s a big year,” Toavs said. “This year we’re about to double that. These are projects we’ve been thinking about and planning for some time. For many factors, they all hit at once.”

Other large transportation projects include the Van Buren interchange at I-90 and the reconstruction of Russell Street – the largest single project in Missoula. Several projects are taking place along the interstate corridor in Frenchtown as well.

Like those, the Blackfoot Bridge project was overdue.

“Our interstate system is plus or minus 50 years old, and we were seeing some settlement at the bridge ends,” Toavs said. “It was nothing catastrophic, but it was a good time to address them and get it taken care of. The interstate is our highest priority.”

As part of the new bridge, a lit trail will cross below the bridge on the west end, a feature that coincides with completion of the new Milltown State Park. Trail work is underway and the park is set to open this summer.