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Grist Mill Bridge Open to Traffic with AIT Bridges Composite Beams

Updated: Sep 14, 2021

Four loaded dump trucks weighing approximately 260,000lbs, load testing the bridge outfitted with sensors.
Grist Mill Bridge Load Testing

AIT Bridges, a division of Advanced Infrastructure Technologies (AIT), a designer and supplier of composite bridge systems and structural components, announced that, in conjunction with The Maine Department of Transportation, after the December 31st load testing, the replacement of the Grist Mill Bridge has opened to traffic, located on Route 1A , in Hampden Maine.

The former span was constructed in 1950 and was comprised of three bridges built one on top of the another. It has been replaced with a new span consisting of five composite beams manufactured at AIT Bridge’s Brewer, Maine facility. The technology was developed in cooperation with The University of Maine’s Advanced Structures and Composites Center.

The Grist Mill Bridge spans over the Souadabscook Stream which is an environmentally sensitive tributary of the Penobscot River. This bridge replacement is part of a project that includes reconstruction and paving work on an almost two-mile-long stretch of Route 1A. The total cost for the project is approximately $8.9 million.

AIT Bridges' composite bridge systems are designed to last over 100 years, at least 30 years longer than the average steel bridge. Additionally, because its bridge systems use composites instead of steel, they need little to zero maintenance over their lifecycle. The use of sustainable, environmentally friendly (low carbon footprint) materials results in a low impact solution to the aging bridges in the U.S.

AIT Bridges would like to thank the Maine businesses and agencies that helped make this historic project possible: MaineDOT, UMaine’s Advanced Structures and Composite Center, T Buck Construction, Dashiell Transportation, TY Lin International (Falmouth, Maine Office), Calderwood Engineering, Composites One LLC (Rockland, Maine Distributor), TexTech Industries, Portland Bolt, N.S. Giles Foundation, Inc., Lee’s Concrete, Owen J. Folsom, Inc., and Hammond Lumber.

Ken Sweeney, P.E., ENV-SP & Bill Davids, P.E.

“We’re so pleased to have lent our engineering expertise to the replacement of the Grist Mill Bridge in Hampden,” said Ken Sweeney, President and Chief Engineer, AIT Bridges. “We wanted to ensure that the construction that took place in 2020 would be long lasting and resilient. By using materials made in Maine by Maine craftspeople, this bridge will stand the test of time.”

Today, AIT Bridges offers the composite arch bridge system and composite beams; two building blocks capable of replacing most bridges across the country. For more information about AIT Bridges, please visit:

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About AIT Bridges AIT Bridges, a division of Advanced Infrastructure Technologies, is the leading producer of innovative composite bridge solutions, providing a unique tailored customer experience. We aim to provide cost-effective and high-quality composite bridge solutions to meet today’s complex design, durability, and environmental challenges.

Our systems utilize components from the 'Bridge-in-a-Backpack' technology, developed over an 11+ year period by the Advanced Structures and Composites Center at the University of Maine. The goal was to develop a rapidly deployable bridge technology for the military. In 2008, Advanced Infrastructure Technologies (AIT) was formed to commercialize the inflatable arch technology. AIT Bridges expanded the composite product line and designed a composite tub beam system built from the original technology. The resulting composite tub beam bridge system utilizes advanced composites materials to produce a rapidly constructed bridge system that offers an extended lifespan with little to no maintenance.


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