In Austin, Minn., multiple bridges are being repaired or replaced as part of a $50 million I-90 reconstruction project. I-90 is considered an important national east-west route that connects many population centers in the United States.
"The bridges are reaching the end of their useful design lives," said Mike Dougherty, Minnesota Department of Transportation (MnDOT) District 6 director of communications and public engagement. "They provide important links for motorists within the community, as well as connectivity to the state transportation system. Most of these bridges were built in the late 1950s when the interstate highway system was constructed through this region."
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Dougherty noted that Oakland Avenue bridge construction has already been completed.
"It was the first bridge in the three-year project, and it went well. With six sites through the I-90 corridor, coordination is important to ensure that the community has access, so this was a good start, and provided insights to the team on further work for years two and three."
The primary contractor is Ulland Bros., of Albert Lea, Minn. The bridge contractor is Lunda Construction of Black River Falls, Wis.
Construction related to 4th Street NW started late last year, with demolition taking place in mid-November. Completion is expected in late 2025.
"The beams have been set, and the deck poured," said Dougherty. "There's significant work for retaining walls in this area around the structure that continues as crews build the bridge.
Sixth Street NE includes an eastbound and westbound bridge. Eastbound was repaired last year, and westbound repairs started this spring. Westbound will be finished and reopen this fall. This is not a replacement, however.
Dougherty explained that overseeing numerous bridge projects is no small task.
"It's a challenge we knew would exist, but it's one that our team is able to handle. It starts with a good plan and good project manager but also relies on each partner, bringing their best efforts. All of us carry that common concern about safety for our workers on site, as well as the public that travels through these work zones."
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I-90 bridge work will enhance walking, biking and riding conditions and help keep pedestrians safe.
"There are improved, wider pedestrian/ bicycle paths across the bridge, as well as crossings of the streets. People who use the Hwy 105/Oakland Avenue bridge for their daily walks and pedestrian travel to get to their destinations have already commented to us how they appreciate the improved crossings.
"We'll also have connections to local and regional trails on several of the bridges or the facilities at the bridge that will help connect to new improvements. We're replacing a pedestrian/bicycle bridge across the Cedar River with a much wider bridge to replace the narrow crossing. We've worked with the local bicycle community to gather their input in advance."
Dougherty explained the original plan in 1955 was for a northern bypass in Austin for busy Highway 16, which runs east to west and through the bustling and growing city. It was going to number as Minnesota State Highway 252. The Federal Aid Highway Act of 1956 was passed by Congress, providing a 90 percent federal to 10 percent state funding ratio for the building of the interstate highway system.
Hwy 252 was replaced with Interstate 90. It still followed very closely the same proposed bypass route planned. In late 1955, it was announced that the first of the interstate highways to be built in Minnesota would be the bypass portion on Austin's north side. The question of how Austin got this many interchanges is puzzling, but the design came along before the interstate designation and then the project kicked off quickly, so there appears to not have been much time to change.
"The American Association of State Highway Officials and the Federal Bureau of Public Roads developed guideline standards after the 1956 federal highway act that included interchange spacing guidelines, but it appears those came too late for this project," said Dougherty.
Regarding current traffic interruptions, "We have used detours on some ramps or detours while a bridge is not available. We have regular reminders of what is closed and what's open. There have been the usual adjustment periods for traffic when a ramp or route is closed for a length of time, but people do adjust.
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"We've utilized overnight detours of I-90 during beam placement, deck pours or other work that needs to take place over the lanes of live traffic. They've gone well, despite the disruptions they create for people."
The project includes a $25 million federal Bipartisan Infrastructure Law grant.
This was an important piece to allow us to do all this work at once," Dougherty said. "With the inclusion of this federal funding, it allowed us to use available state funds elsewhere on other projects to ensure that we are maintaining the transportation system in southeastern Minnesota."
Dougherty said those who travel in these areas will notice significant improvements.
"They will have updated bridges and other facilities that meet the current safety and design standards, as well as better accommodate the current uses, vehicles and routes people travel. The bridges help connect the community but also support the industries in Austin."
Jim Roberts, MnDOT District 6 construction resident engineer and project manager said with construction taking place in an urban section of I-90, workspace is limited.
"The most challenging location is the 4th Street interchange where a 160 ft.-wide single point bridge is being constructed, along with numerous retaining walls and ramps getting reconstructed.
For the 4th Street bridge, the first order of business was bridge demolition, followed by a month-long soil surcharge at the abutments. In January, crews removed the surcharge and began construction of the abutments and retaining walls. Since then, the abutments have been constructed, beams placed, three retaining walls have been built and the deck was poured in mid-July. Crews will continue with constructing the raised medians, sidewalks, pedestrian ramps, signal systems, concrete barrier, approach panels and applying a low slump concrete overlay.
MnDOT photo
Nighttime beam setting on the 4th Street northwest bridge requires coordination with numerous individuals to make it go safely and successfully.
"This includes the contractor and our subs, law enforcement, city and county officials and the public. We have to detour traffic overnight when the traffic is lightest, ensure that it's done safely and be certain that the beams arrive. Workers who specialize in this activity have to be ready and in place, and we watch the clock, while also monitoring the safety of all involved. It went well in placing 21 beams for this bridge."
The bridge is a single point interchange design. This allows for efficient traffic flow, especially at busy intersections, by minimizing the number of signal phases and the number of conflict points between different traffic movements. The bridge is a single-span structure. It's approximately 110 ft. long and 160 ft. wide.
Roberts said building the new interchange requires teamwork, from design consultants working with MnDOT specialty offices to MnDOT's construction staff partnering with the various contractors.
"It has also required a significant amount of materials. To build the bridge it will take approximately 300,000 pounds of reinforcement steel; 1,800 cubic yards of structural concrete; 9,230 square feet of sidewalk concrete; and 2,300 feet of concrete reinforced beams."
Roberts said resurfacing for both I-90 bridges over 6th Street has gone well.
"It's at a location adjacent to the Hormel Foods plant, so there was attention given to truck turning movements and routes and regular communication on construction impacts that may affect the work that occurs there."
As for construction of the two new I-90 bridges over the Cedar River, the westbound bridge is currently being replaced. The old bridge has been demolished, and crews are beginning the process of building a new pier and abutments.
As crews continue their work, there are a few sites noted as possible areas containing contaminated materials. MnDOT and the contractor will test these areas as excavation activities take place. So far, these sites have tested negative for contaminants.
To carry out work on these projects, multiple cranes are needed on site, along with excavators, trucks and other equipment. Chief materials include concrete, reinforcement steel, steel piling and aggregates.
The elements, said Roberts, have not been a significant issue to date.
"We live here, so we're used to the changes that weather can bring to the work. There have been rainy times that cause work adjustments, but last year was relatively dry, so that was a benefit. Crews also worked through most of the winter on the 4th St NW bridge and managed through our cold winter temperatures and snow events."
He added, "We all take pride in our work and the responsibility it carries to ensure that it's done right, done well and meets the specifications we've set to last long into the future. We uphold those efforts to meet the quality expectations we have."
Bridge work related to 14th Street / Hwy 218 North and 21st Street / Hwy 218 South has yet to be performed. This construction will take place in 2026. CEG
