MANKATO — Despite delays and climbing costs, a bridge unique in the nation will become a striking centerpiece of Mankato’s park system and the region’s network of trails by this time next year.
“It’s really the last one existing in Minnesota today,” interim Mankato Public Works Director Karl Keel said of the 1873 Kern Bridge.
The bowstring arch bridge, believed to be the longest of its type in America, was no longer being used and was on the verge of collapsing into the Le Sueur River in South Bend Township when state and county officials rescued it in 2020. Disassembled into its hundreds of individual iron pieces and placed in storage, the bridge will be put back together and made ready for walkers and bikers by sometime next summer or fall.
But it won’t happen without a hefty bill.
“It has gone up significantly from the feasibility report time,” Keel said of detailed project analysis presented to the council in June of 2024.
With the construction bid approved by the City Council Monday night, the total project cost will now be more than $10.5 million rather than the $8.3 million estimated 16 months ago.
At that point, no funds from Mankato’s park reserves were slated for the Kern Bridge project. Now, $1.44 million is to be used to help bridge the gap in funding, including $580,000 that had been set aside for a splash pad to be constructed at a yet-to-be-chosen location in Mankato sometime in the years ahead.
“That’s been sitting out there for some time,” Administrative Services Director Parker Skophammer said of the funding for the unscheduled splash pad.
A revised financing plan will also inject an additional $1.96 million of federal funding into the project. Those funds were recently identified by the Minnesota Department of Transportation to keep the project on track after construction bids came in higher than anticipated. And the level of financing from Mankato’s local sales tax will rise by more than $250,000, increasing the sales tax contribution for the bridge to $1.16 million.
Although council members have found themselves dealing with much more than they bargained for financially when they agreed to pursue ownership of the bridge in 2020, they unanimously authorized the reassignment of the $580,000 in splash pad funds and the approval of the contract with low-bidder Redstone Construction.
When the project was put out for bid, a private engineering firm estimated that it would cost $7.28 million to reassemble the bridge and place it on newly constructed piers and abutments over the Blue Earth River between the two Mankato parks. The three contractors who were willing to tackle the project had different ideas.
When bids were opened more than five weeks ago, they ranged from $1.1 million to nearly $2 million above expectations, with Redstone offering the lowest price at $8.38 million.
The project costs rise to $10.1 million when fees paid to the engineering firm are factored in and to $10.5 million when the expense of an associated connecting trail in Land of Memories Park is included. That total includes a 5% contingency for unanticipated expenses that arise before completion of the work.
That’s more than quadruple what municipal engineers five years ago told the council to expect to pay for the project when the elected officials agreed to pursue the bridge.
The process started with MnDOT and Blue Earth County saving the bridge from demolition. Next, MnDOT offered up the bridge to cities and counties interested in taking ownership for reuse as a pedestrian or bike trail amenity, but state officials warned that refurbishing and reassembling the Kern Bridge would cost “at least $1,500,000.”
Mankato’s proposal won the competition, but the city has now spent more than that MnDOT estimate just on contracts with the St. Paul engineering firm of Short, Elliott, Hendrickson to complete designs and oversee construction — $1.7 million in consulting fees.
From the onset, Mankato officials knew that their plan for the bridge would cost more than the MnDOT estimate because the 189-foot bridge was not long enough to span the entire gap between Sibley and Land of Memories parks. That meant that the Kern Bridge would have to be supplemented with the construction of a section of new bridge on the Sibley Park side and an elevated section of trail in a flood-prone area on the Land of Memories side.
Even with those added elements, staff in the city’s Public Works Department predicted in August of 2020 that all of that work could be accomplished for $2.53 million and the bridge could be open for use by 2024. Keel said Monday night that a lack of understanding about the poor soil conditions in the area, plus exceptional inflation in construction costs since 2020, were to blame for the hugely elevated costs.
While bringing the Kern Bridge to Mankato is turning out much more expensive than planned, the final result could still become a signature element of the municipal park system and of the broader regional trail system.
The resurrection of the bridge will also give Minnesota some bragging rights over its Hawkeye neighbors to the south. Since the Kern Bridge was disassembled, the 156-foot Freeport Bridge near Decorah, Iowa has claimed to be the longest bowstring arch bridge in the United States.
The Freeport Bridge will be back in second place a year from now if the Mankato project stays on its current schedule. Keel said piers will be constructed this fall and winter when river levels are low, even as the 152-year-old iron pieces of the Kern Bridge are cleaned, repaired and painted.
The bridge will be reassembled next year and placed by cranes on the newly constructed piers and abutments. Although some final portions of the project might have to be wrapped up in the spring of 2027, Keel is confident the span will be open for use in 2026.