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Transportation agencies weigh Blatnik Bridge’s life span

The Blatnik Bridge is seen from St. Louis Bay in September. The bridge opened in 1961, and transportation agencies have started the process of considering its replacement. (Bob King / rking@duluthnews.com)

One of the major bridges in the Twin Ports is old enough now that local transportation agencies have started the process of considering its replacement.

The Blatnik Bridge that carries Interstate 535/U.S. Highway 53 and almost 23,000 motorists per day across St. Louis Bay between Duluth and Superior turns 55 in December.     

“It’s getting up there in age,” said Kevin Rohling, a local Minnesota Department of Transportation bridge engineer, “and it’s getting more and more difficult to maintain.”  

Bridges as old as the Blatnik Bridge, built between 1958-61, “have been constructed with a theoretical design life of 50 years,” said a recent MnDOT long-term planning report, titled Minnesota GO.

“That can be about their life cycle,” said Ron Chicka, director of the Duluth-Superior Metropolitan Interstate Council. “MnDOT has some hard decisions to make.”

An ongoing management study is being conducted with the help of contracted engineers to determine a course for the bridge beyond its next scheduled maintenance in 2020. According to its website, “MnDOT is developing a plan to schedule appropriate maintenance, preservation, rehabilitation and, ultimately, replacement of this structure.”

The results of the study have been pushed to the end of the year from an originally scheduled fall release.

“We’re getting close to the answers,” Rohling said. “We wanted to plan out the maintenance of the bridge depending on how long we think we want to leave before we replace it or do a major rehab.”

The bridge just underwent the replacement of a cracked gusset plate along with almost two dozen other corroded ones. To hear the experts tell it, there is a wide range of life spans for bridges such as the Blatnik, meaning some last longer than others. But being a steel truss bridge “with so many connection points and members” — and given the use of road salt to go with freeze/thaw cycles — makes the Blatnik more problematic from a corrosion standpoint, Rohling said. There are things aging on the span that aren’t visible to the naked eye and, simply, “it’s a difficult design to maintain,” he said.     

The transportation departments of Minnesota and Wisconsin share costs involved with both the Blatnik and Bong bridges connecting Duluth and Superior. But in terms of management, MnDOT manages the Blatnik and the Wisconsin Department of Transportation takes the lead on the 2-mile-long Bong Bridge that opened in 1984. The bridges that were built for a combined $85 million are among the most important pieces of infrastructure in the Northland and garner fierce attention from the local agencies.    

“When we talk about somebody being a lead agency, it’s become (to mean) bureaucratic lead — the ones who do the administration,” said Tom Beekman, WisDOT’s Northwest Region planning chief, “but when you walk into a working meeting it’s arm-in-arm.”

Peering into the future of the Blatnik Bridge is also an “iterative process,” said Beekman — one that features planning agencies looking at things from unique perspectives.

At some point in the future as plans congeal around funding, the parallel tracks will turn inward and converge into a singular way forward. But until then concerns come from all angles.  

The issue of money

In its long-range plan titled Connections 2040, the local Metropolitan Interstate Council estimated $175 million for the Blatnik for “reconstruction.”

The dollar figure itself is somewhat insignificant, said Chicka, who called it a “placeholder,” since it’s not yet tied to any planned project or budget. A similar early $500 million estimate for the reconstruction of the “can of worms” section of Interstate 35 through Duluth was ultimately pitched to the U.S. Department of Transportation as a $244 million project.  

The value of the Blatnik number is that it lets the feds know the bridge is a future priority. Transportation funding, sources all say, is a 10-year proposition — and a replacement or major overhaul of the Blatnik is not in anyone’s budget so far through 2026.  

Like the Duluth Seaway Port Authority, the MIC is a federally mandated agency with an appointed board. Chicka and his staff work with all local units of government to ensure cohesive development of transportation infrastructure.

The MIC’s project endorsement of the Blatnik is important when it comes to securing federal funding, as decision-makers tend not to ask deeper questions unless the local metropolitan planning organization supports it.

And while the can of worms project funding was rejected earlier this year by the federal DOT, it figures to gain approval at some point in coming years. The Duluth-Superior MIC continues to enthusiastically support it for surface transportation grant funding — billions of dollars made available by Congress through 2020.

A reconstructed I-35 interchange through Lincoln Park — which eventually would tie into a new Blatnik Bridge — has become the MIC’s priority, as it would address safety issues and weight restrictions on freight that make the can of worms and its nearly 30 bridges outdated and unkind to motorists and commerce.  

“That application figures to be out again very soon,” said Chicka.

Blatnik future a blank slate

On its website, MnDOT explains that it inspects the Blatnik Bridge annually and monitors as necessary. Were something ever to be discovered that posed imminent danger to the public, “the bridge would close immediately for repair,” it said.  

Barring that, the agency allows non-critical repairs to accumulate until it’s time to justify a full project.

“Until we know when we’re going to replace the bridge,” Rohling said, “what we do in the meantime is keep it in service.”

The upcoming management study report will lay out when the bridge will need its next painting and how future repairs can be scheduled with a minimal disturbance to traffic.

“This plan will help us make decisions and manage the bridge in the most efficient way,” Rohling said.  

But at this point, nobody knows what a bridge replacement or overhaul will look like:

  • Will it be a matter of replacing spans in intervals that will allow for the bridge to remain partially open through construction?

  • Will there be another bridge built beside the current one?

  • Will the Blatnik be shut down in total for a minimum of two years?

  • Or will things unfold in unexpected ways, such as changing the location of the bridge?

“You learn in this business to never say never (to anything),” Beekman said.  

The Blatnik Bridge shut down completely for about 10 months as part of a major reconstruction project in the early 1990s. There have been partial lane closures for renovation work several times since, including in 2012-13 and again earlier this year.

Looking ahead, environmental laws, financial realities, societal input and political sway can shape a project as it comes into clearer view — either broadening or narrowing its possibilities. But one thing is known, Beekman said: “You find out the need for two bridges real quickly when there is only one.”

Farther west, Canadian National Railway owns and operates a third bridge  — the 106-year-old double-deck Oliver Bridge in Gary-New Duluth — that is not generally considered a peer of either of the main arteries across the water between Minnesota and Wisconsin.

The Oliver Bridge is currently undergoing a multi-year modernization of its own. A quarter the length of the nearly 8,000-foot Blatnik, CN tends to measure the Oliver’s traffic in terms of trains, with 20 per day crossing the bridge.

Its use by motorists pales compared to the Blatnik, which rises so high above the water — 120 feet to allow lake freighters clearance — that windy days can make themselves all too obvious to motorists.

‘Accelerated’ process

The Blatnik will connect with whatever configuration replaces the can of worms interchange on the Duluth side of the bridge. There also is much to consider on the Superior side.

The bridge currently features an interchange at its Superior entrance with an off-ramp before emptying southbound traffic onto Hammond Avenue. Updating the Blatnik poses the opportunity to address issues with the current situation.  

“From a traffic flow and freight standpoint an alternative would be preferable,” Chicka said.  

The city and WisDOT are having ongoing discussions about initiating studies that would identify current conditions, including stress points, and offer alternatives.

“A lot of historical groundwork is in place but we’ll be updating a lot of stuff,” Beekman said.

What comes out of the studying and planning is anybody’s guess. But Beekman is of the mind that all of the issues intertwined with an aging Blatnik Bridge will be coming to resolution sooner than later.

“A major bridge replacement in 10 years is very fast,” Beekman said, offering that planners like as much leeway as possible working back from an ideal of 30 to 40 years. “But in terms of how this is shaking out, what we’re looking at is a fairly accelerated study process. We have to get on it and go.”

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