Making History Again

When a historical bridge in Maine had to be demolished and rebuilt, the question was how to do it and still preserve a landmark

By Tina Grady Barbaccia

When the historical bridge in Norridgewock, Maine, had deteriorated to a point where it had to be either demolished or rehabilitated, a delicate situation presented itself. The “concrete bridge” as the locals called it was part of the community’s character and charm — and part of the town’s emblem. No one wanted to see it razed, but the bridge needed to provide a safe and efficient river crossing. This made for a very sensitive situation, but one that was able to be worked out. The bridge opened to traffic this summer.

The design needed to be “both contemporary and fitting for the setting and the history of the site,” according to Wayne Frankhauser, project manager for the covered project. The challenge was clear: A bridge had to be designed in a way that was similar to the existing structure but incorporating as many modern design and construction techniques as possible.

The new Norridgewock bridge in Maine is the first modern concrete tied-arch bridge built on the East Coast in 50 years.

Complicating plans further was the fact that the bridge would be built with federal and state money. The Federal Highway Administration (FHWA) and Maine Department of Transportation (MaineDOT) would have to agree on a plan. Because of the historic significance of the bridge and historic buildings close to it, federal law requires that the Maine Historic Preservation Commission also had to be in agreement, according to MaineDOT. After conducting a study from 1998 to 2004 to evaluate four crossings — both east and west of the current covered bridge — MaineDOT and FHWA came to the conclusion that although rehabilitating the bridge was an option, it was recommended that the current bridge be removed “due to its poor condition, narrow width and outdated height.” A new bridge would be built on the site.

Creating a Worthy Landmark

In 2004, the FHWA, MaineDOT and the Maine Historic Preservation Commission came to an agreement on the bridge’s design plan in a document known as a Section 4F statement. (See “Norridgewock Bridge Project Unique Stipulations” sidebar.)

The Kennebec River Bridge prior to demolition. It was an eight-span bridge that included four 100-foot tied-arch spans.

After all the stakeholders in the project had come to an agreement on the bridge design selected, they engaged the community with both a public meeting and an informal survey. When asked their preference about the two design options, the response was divided, with neither design being a clear winner.

The plans began to move forward. “Though we know [the] decision won’t please everyone, it’s time to move forward with construction plans,” Frankhauser said after the selection of the bridge design. Earle G. Shettleworth Jr., director of the Maine State Historic Preservation, fully supports the design decision.

He notes that the covered bridge in the current condition is “a bold statement of the modern age . . . one of Maine’s most significant 20th-century bridges.” However, with the two options that met the project’s purpose and need, “one embellishes what is otherwise a fairly standard girder bridge,” Shettleworth says. “The second uses a 300-foot center-arch span employing the latest design concepts. I firmly believe that the arch option is the only one that will result in a bridge [with a] design both functional and noteworthy, creating in the process a 21st-century engineering landmark worthy of this historic crossing.”

Combining Yesterday, Today and Tomorrow

When the bridge was first constructed in 1870, it was built as a 538-foot-long bridge with an arched portal and a gambrel roof. Laminated wooden trusses were later added to the inside of the bridge to increase the capacity. The 1870 bridge was lost to a flood and replaced in 1928. The 1928 structure was an eight-span, 600-foot-long bridge with four 100-foot concrete tied-arch spans and four concrete T-beam approach spans, considered one of the most advanced designs of the time.

The contractor is placing the concrete for the arch rib for the new bridge. Note the two in-water piers and the NEBT approach span that have already been completed along with the falsework.

Now, the historic structure is again incorporating some of the latest in bridge design technology. A 300-foot concrete tied-arch with New England Bulb Tee (NEBT) approach spans was chosen for the design as the preferred alternative, to minimize substructure cost while mitigating for the loss of the existing historic concrete tied-arch structure.

The concrete tied-arch for the new $21-million bridge is the first modern concrete tied-arch — to the best of all the stakeholders involved in the bridge’s knowledge – built on the East Coast in the past 50 years, says Keith Wood, P.E., senior project engineer for Kleinfelder|SEA, the consultant to MaineDOT on the project and the firm that conducted the preliminary study and the final design on the chosen bridge site.