Photo: National Park Service (public domain).
Photo: National Park Service (public domain).
April 21, 2019 09:33 AM
MANKATO, Minn. (AP) — The Kern Bridge just south of Mankato has remained standing for more than half of the United States’ existence.
The longest of its type remaining in America, the bridge just survived its 145th Minnesota winter and the spring torrents that ensued.
If all goes according to plan, the bridge’s marathon assignment spanning the Le Sueur River will end late this summer when the wrought iron structure will be dismantled, put in storage and left to await a yet-to-be-identified opportunity to rise again as a bike-pedestrian overpass at some other location.
“I’m hoping that this area will find a place for it, but if it goes somewhere else in the state, that would be OK, too,” said Lisa Bigham, acting state-aid engineer for the Minnesota Department of Transportation’s Mankato district.
For Bigham and other engineers in the area, the one place they didn’t want to see the bridge is at the bottom of the Le Sueur River, followed by a trip to the scrap yard.
“It isn’t a question of if it will fail, it’s when,” said Blue Earth County Public Works Director Ryan Thilges.
Bigham’s yearslong effort to find funding to save the bridge found success just before Christmas, which puts an end to fears that it would be torn down and sold for scrap, the Mankato Free Press reported. But the Kern Bridge still had to withstand one more attack by Minnesota’s climate — a brutal winter that brought nearly 100 inches of snow that melted into major spring flooding.
Bigham was watching the Le Sueur River water levels closely last month, knowing the bridge abutments were severely eroded by previous floods. And when the water was at its highest, she made a visit to the bridge, which is on a township road between County Roads 1 and 90.
“I drove out during the high water to make sure it was still there, and it was,” she said. ”... I was worried it was going to fall in the river after all the snow. That would have been a shame after finally lining up this money.”
It wasn’t just locals rooting for the Kern Bridge to hang on one final time.
“The fact that the Kern bowstring made it through another winter is tremendous,” said Julie Bowers, who works with an Iowa-based bridge preservation organization. “Watching another one hit the water would have been just horrible.”
The Kern Bridge’s design — a “bowstring arch through truss” — and its length make it remarkable to engineers. The name stems from the design’s similarity to an archer’s bow.
At 188 feet, the bridge is much longer than a typical bowstring bridge. A 216-foot version in London, Ontario — the Blackfriars Bridge — is the only one in North America that’s longer.
Thilges said the Kern Bridge is particularly impressive considering it was built just a handful of years after the end of the Civil War.
“When you think what was available for technology at the time, that it’s still standing is really remarkable,” Thilges said. ”... The craftsmanship and design that went into it, we certainly want to preserve that.”
Bowers got into bridge preservation after her family picnicked near a picturesque bowstring bridge in Poweshiek County, Iowa, and later saw the bridge fall into the river when county officials declined to invest in it.
Bowstring bridges deserve to be saved both because they’re rare and because they combine beauty and functionality, she said.
“The gracefulness of the engineering,” she said. “What looks so light can carry 140 years of traffic.”
Bigham talked of the iron latticework, the wooden bridge deck, and — most of all — “it’s simple but beautiful arch.”
“Just think, it was built for horses and buggies,” she said. “It’s just amazing that it’s still out there.”
The Kern Bridge has enough allure that, even if it’s officially closed, pedestrians continue to come. Thilges said there’s ample evidence that more than a few adult beverages have been consumed on the bridge. Bigham heard a story of a couple using the span as the setting for a full-scale romantic dinner.
“Lots of people know about it,” she said. “Lots of people have taken photos on it. Lots of people have gone out there doing fun things. Or naughty things.”
All that activity is the definition of “an attractive nuisance,” and the bridge’s owners — Mankato Township owns the east half and South Bend Township owns the west —have been worried about liability issues ever since it was closed to through traffic in 1991. After a quarter century of trying to find someone to take possession of it, supervisors of the two townships agreed last summer to contribute up to $10,000 each to remove it for scrap.
Thilges credits Bigham with finding the money to offer the bridge a reprieve.
Already, $40,000 has been provided to develop plans for its removal and another $300,000 is set aside for disassembling it and placing the pieces — some of which will be 40 feet long — in storage. Additional money is available to cover 80% of the cost of restoration and reassembly at a new location, something that a consultant estimated could cost as much as $1.2 million.
All of it is federal funding leftover from an allocation for work on the Stone Arch Bridge in Minneapolis. Blue Earth County is charged with overseeing the project, which is expected to be underway late this summer or in the fall.
“We would remove the bridge, disassemble it on site, place it in storage vessels,” Thilges said. “It would be held by MnDOT for up to 10 years while they look for a place to use it —likely as a pedestrian structure.”
Thilges knows there will be naysayers who will wonder why so much money is being dedicated to an old bridge that’s no longer capable of carrying vehicular traffic. While the federal dollars couldn’t be used for resurfacing highways or filling potholes, there’s still tax dollars.
“We want to take care of the infrastructure that’s serving us, but in the same breath we also want to preserve history,” he said.
While MnDOT could dispose of the Kern Bridge if no new user is found in the next decade, there’s widespread confidence it won’t come to that.
“Just because of the interest I’ve seen already,” Bigham said of her optimism that a new owner will be found. “And the fact that they need to come up with only 20% of the cost.”
With the federal government covering the bulk of the expense, reusing the Kern Bridge would be cheaper than building a new 188-foot trail bridge, she said.
While the new owner could move the structure to elsewhere in Minnesota or even to another state, local options have been explored. Most of them, however, are problematic.
The city of Mankato’s wish list has long included a pedestrian bridge connecting Sibley and Land of Memories parks, which are separated by the Blue Earth River. The Kern Bridge isn’t long enough for that.
Minnesota State University once considered adding a pedestrian bridge over Stadium Road, but Thilges said crosswalk improvements have since been added to the street and he’s heard of no interest in recent years of installing an overpass.
The Minnesota Department of Natural Resources considered using the bridge to span Highway 68 and provide a pedestrian-bike connection between the two sections of Minneopa State Park. The DNR’s interest waned because its trail bridges have load requirements allowing heavy equipment, including snowplowing vehicles, to cross them — something the Kern Bridge couldn’t handle without major retrofits.
A pedestrian bridge is tentatively planned over Highway 22 near Prairie Winds Middle School, but the Kern Bridge might be a bit too short for that duty, said Mankato Public Works Director Jeff Johnson. The bridge abutments would be within the Highway 22 right of way, which MnDOT might object to. Plus, the bridge — which is on the National Register of Historic Places — has always existed in a rural, scenic setting spanning a river, so historians might push for a similar site for its next life.
Mankato has a setting like that along the Minnesota River Trail. A deteriorating bridge over a ravine, about midway between Riverfront Park and Highway 14, needs to be replaced in coming years. In that case, the Kern Bridge is probably too big for the job, Johnson said.
“It’s about twice as long as what we need,” he said.
The result would be half of the bridge resting on land, not allowing it to strut its length. And the site also isn’t conducive to giving people a side view of the elegant span.
Johnson hopes the bridge will find a new home that’s appropriate — both aesthetically and functionally — even if the location is not in the immediate area. Because of its place on the National Register, the bridge would always have a plaque detailing its birthplace and first 146 years in rural Mankato, he said.
“If somebody needs it right away, we should give it up and let them use it.”
Bowers, the preservationist, disagrees. That bridge in Iowa where she picnicked was pulled from the river and sent to Delaware for use in a state park. She’s glad it still exists, but she thinks the Mankato area would miss the Kern Bridge if it faces a similar fate.
“Is it a loss to the locals? Yes, it’s a huge, huge loss.”
For Thilges, preservation would be a victory regardless of the bridge’s ultimate location.
“If it does come to fruition and finds another home and serves another purpose, it certainly would be a feather in the cap for me, for county staff, for MnDOT, for the townships. It wouldn’t have been possible without all those partners,” he said. ”... It took us a while, but we’re finally on a path.”
Updated: April 21, 2019 09:33 AM
Created: April 21, 2019 09:24 AM
(Copyright 2019 by The Associated Press. All Rights Reserved.)