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Nov 22

The Bertram “Blue” Bridge is Moving!

Posted on November 22, 2022 at 9:09 AM by Britt Nielsen

Bertram Blue Bridge

This month, the Linn County Secondary Road Department started the Bertram Bridge replacement and relocation project. The Bertram Bridge, also known as the Blue Bridge, relocation project includes replacing the current 146-year-old bridge with a new IDOT standard concrete beam bridge that will be able to carry legal loads (80,000 pounds or less) and relocating it to the Indian Creek Nature Center where it will be used on their trail system. Due to the existing truss bridge being a registered historic structure, the Linn County Historic Preservation Commission is participating in this project with the Secondary Road Department and Indian Creek Nature Center to ensure the bridge is preserved and properly signed in its new home.


History of the Bridge

The Bertram Bridge was built in 1876 by the Wrought Iron Bridge Company (WIBCo) using a design patented in 1876 and was presumably one of the first bridges to use the new design. WIBCo’s patented design was a variation of a standard Pratt truss configuration, employing double-intersecting counter members radiating outward from the center of the span. This early wrought-iron truss features four timber stringer spans at its north approach and is supported by a combination of stone and timber abutments. With no alterations on record, this bridge continued to serve vehicle traffic until 2022 at 146 years old.

This bridge has survived many floods, most notably in 1993 and 2008. Thankfully, the high water was mostly backwater from the Cedar River, which did not carry a damaging current. Multiple repairs have been made to the bridge over the years. Per inspection records, the timber deck surface was replaced in 1926, 1940, 1954, 1987, and 1996 and the timber approach spans were completely reconstructed in 1987. To protect the integrity of the steel, the truss was painted several times, most notably in 1991 when it received a royal blue treatment earning it the “Blue Bridge” nickname.


Project Timeline

The bridge project started at the beginning of November 2022 with tree and brush clearing. The contractor is now working on constructing the substructure for the new bridge and will start construction on the superstructure in the spring. The existing bridge will be relocated to its new home at the Indian Creek Nature Center in May or June 2023 and the project is scheduled to be completed in August 2023.

“We are very excited about this project,” said Linn County Secondary Roads Assistant Engineer Garret Reddish. “The new bridge will benefit the driving public, while the old bridge will benefit trail users and the Indian Creek Nature Center.”

The Linn County Secondary Road Department will provide updates throughout this project. Sign up to receive text or email updates on the Bertram Road Bridge Replacement Project under the Alert Center on the NotifyMe page. You can also watch the project progress via a livestream on our website.