Linn’s oldest bridge moving to Indian Creek Nature Center

The oldest bridge in Linn County will be lifted up by cranes and put on a truck to haul it about a mile away to the Indian Creek Nature Center, where it will become a pedestrian bridge.

The Bertram Bridge, also known as the Blue Bridge on Bertram Road near the nature Center, was built in 1876. The steel truss bridge’s design was brand-new for the time, and over the next 146 years no major alterations have been made. Its timber deck surface has been replaced several times over the decades and, in 1991, it received a royal blue color treatment, earning its nickname.

Throughout its life so far, it served vehicle traffic and survived multiple flooding events, most notably in 1993 and 2008.

“The bridge is old — very old,” Linn County Assistant Engineer Garret Reddish said. “Fire trucks, semis, snow plows really can’t go over it. And we have records from the 1970s talking about replacing it, so this is a project around 50 years in the works.”

Reddish added that moving and repurposing the bridge is the ideal scenario.

“It’s a historic structure, so anytime we’ve talked about replacing it, we get resistance,” Reddish said. “But when the Indian Creek Nature Center was ready to accept the bridge, that got rid of the resistance. It’s in the same general area and people will still be able to use it.”

Indian Creek Nature Center Marketing Manager Eric Hart said repurposing the bridge also is sustainable.

“It’s a really sustainable way for us to add a pedestrian bridge to connect our trails,” Hart said. “It really ties into our sustainability practices that we try to model here. It really fits into our mission.”

The Blue Bridge will arrive to its new location during the Indian Creek Nature Center’s 50th anniversary next year.

“The plan is to put it over a ravine and connect the Cedar Rapids Prairie area to the Stimple Prairie,” Hart said. “From what we've heard, people are excited that the bridge will get a second life and still be around. Especially with that blue color, they really love the look of it.”

Peterson Contractors Inc. of Reinbeck will start around Tuesday to start excavating the creek and working on the substructure for a new bridge to replace old Blue.

“They’re basically going to work on the foundation of the bridge during the winter,’ Reddish said. “That’s common because water levels are typically down and they’re predictable. It’s easier to navigate with frozen dirt as well.”

The bridge replacement project will cost $2,425,608.45 and the truss relocation will cost $184,373.00. The projects are both funded with local-option sales tax money.

The new bridge will be a “typical concrete, two way bridge,” Reddish said.

The project is expected to be complete by August 2023.

Reddish said the Blue Bridge will remain open throughout the winter and into the spring. The plan is for it to be moved around Memorial Day weekend. However, there may be some spot closures during different parts of the winter work.

But the move itself is the key component to the project. Though there’s been careful planning, it’s not guaranteed the old bridge will survive the move.

“We can lift this and it could snap right in half,” Reddish said. “It’s 146 years old. We have a great plan but the age of that steel might be beyond saving. We’re very hopeful we’re not going to break it, but it could happen.”

Reddish said once the bridge is picked up by cranes, it will be set down on dirt next to its old location. Once the foundation is done at the Indian Creek Nature Center, it will get picked up again and hauled onto a large trailer and picked up one more time to be set on its new abutments.

“The truss itself doesn’t weigh that much. It’s more of the size and awkwardness of it,” Reddish said. “The timber deck wood weighs more than the steel truss. So they might dismantle the timber decking, but that’s a lot of work, too, and that’ll be up for the contractor to decide.”

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