The prospect of a tunnel instead of a bridge project was the first question posed to the transportation departments of Minnesota and Wisconsin during an online public meeting Thursday about the future of the Blatnik Bridge.

Nothing is off the table at this point, organizers said — not even a tunnel under the St. Louis River.

“We have posed the question of replacing the Blatnik Bridge with a tunnel, but one parameter we have to review is we have a shipping channel,” WisDOT’s Northwest Region Deputy Director Jessica Felix said. “With a tunnel you have to get under the shipping channel and where do you exit?”

The Blatnik Bridge, carrying Interstate 535 between Duluth and Superior, opened in 1961, and will be 70 years old in 2031 — the year it’s scheduled to finish being either rehabilitated or replaced.

Until then, there are years of engineering to be completed and many decisions to be made — a point Pat Huston, MnDOT project manager, emphasized for community members.

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“Key decision-making is going to happen in the next 12 to 24 months,” Huston said. “We need your help to be all in and interested now.”

Waiting until the engineering is done years from now will be too late to affect the outcome, he said.

The current Blatnik Bridge, with its deck 12 stories off the water, requires more frequent maintenance, resulting in more delays for drivers. Another structural repair project is scheduled for 2021. The bridge is also load-restricted and unable to accommodate oversize loads. It’s inspected annually and remains safe.

“It’s toward the end of its design life,” Huston said.

Organizers raised the question of even needing two bridges between the cities.

“It’s a fair question,” Huston said. “Many of you may be thinking it tonight.”

He cited reasons for the redundancy between the Blatnik and Bong bridges, including to allow for service and lane closures, and freight and emergency response efficiencies.

MnDOT and WisDOT will share the cost of the bridge project, scheduled to begin in 2028.

Placeholding figures have it as a $460 million project, but nobody knows what it will cost at this point. They don’t know what project they’ll be building.

“A replacement might be in the same place or a new location close by,” Huston said. “There’s a whole lot of options on the table.”

The truss at the center of the bridge is a certainty to need to be replaced, Huston said, but the approaches, piers and underwater pilings need further examination.

One of the questions being asked, Felix said, is “what is the smallest and biggest project we need?”

It’s a question that figures to occupy a lot of thought between now and 2026, when preliminary design is scheduled to be completed. Then, it’s onto final design until the start of construction in 2028.

Could it really be a tunnel?

“It’s probably not likely,” Huston said. “But we will consider that option.”