The new 75-foot Grist Mill Bridge on Route 1A in Hampden might not stand out from the traditional steel and concrete bridges that have been installed across Maine for decades. But the structure is the first bridge of its kind, using technology developed by a Brewer business that makes the bridge resistant to corrosion and longer-lasting and easier to maintain as a result.
The bridge — which opened to traffic on Dec. 23 after being closed since April 13 — is the first to use a girder system designed and manufactured by the bridges division of Advanced Infrastructure Technologies in Brewer, which developed the technology with researchers at the University of Maine.
But a bridge type developed in the Bangor area is unlikely to be used only locally. Advanced Infrastructure Technologies said it is slated to bring the design used in Hampden to bridges in Rhode Island and Florida. As it works on growing its technology’s reach, the company has been in expansion mode even as many other businesses have contracted due to the COVID-19 pandemic, according to President and Chief Engineer Ken Sweeney.
“We want to ensure that this technology is used across the world,” he said.
The Grist Mill Bridge has carried Route 1A traffic over Souadabscook Stream for decades. The most recent of the three steel bridges — which were built on top of each other — was built around 1950. In poor condition, they were demolished beginning in April to make way for the new bridge, which is made of composites.
Composites are combinations of two or more materials with different properties that, when combined, become stronger than they are apart. The bridge’s new span features five beams built with fiber-reinforced polymer, a composite material consisting of glass fiber, carbon fiber, foam core and resin.
From top left (clockwise): Chris Powers, Dylan Gagnon, Jesse Perkins and Michael Polk (clockwise) begin building a 76-foot long composite girder at Advanced Infrastructure Technologies in Brewer in August 2019; Advanced Infrastructure Technologies in Brewer use an 80-foot mold at AIT to build a girder that is 76 feet long, 4 feet tall and four feet wide. At far right is a small section of a composite girder; A completed section of the new composite girder at Advanced Infrastructure Technologies in Brewer; Michael Polk and Jesse Perkins, place reinforcement fabric in the 80-foot mold they are using to build a composite girder. Credit: Linda Coan O’Kresik | BDN
The material provides a corrosion-resistant alternative to previous bridge technologies, Maine Department of Transportation Bridge Program Manager Wayne Frankhauser said.
“FRP composites do not rust or deteriorate like a lot of the conventional bridge materials do,” he said. “The bridge itself should last a long time with little maintenance.”
The project came about years ago as the Department of Transportation examined how to rebuild the deteriorating Grist Mill Bridge. The department keeps abreast of new technological developments, and as it was looking into a Grist Mill Bridge replacement, researchers at the University of Maine were running tests on the new composite girders.
The department was attracted by the bridge’s ability to sustain itself without costly renovations or the need to impose restrictions such as weight and traffic limits.
The girder technology “is certainly on the cutting edge,” Frankhauser said. “We’re continuing to develop the product and test it and look at its performance. But we are very interested in it.”
The bridge replacement is part of a reconstruction and paving project along a two-mile stretch of Route 1A costing about $8.9 million. Work is continuing over the spring and summer, with one lane of the Grist Mill Bridge closed for a few days this month for cleanup. The contractor working on the project is Turner-based T. Buck Construction.
Advanced Infrastructure Technologies — located in Brewer’s East-West Industrial Park — was founded in 2009 as a spinoff of the University of Maine’s Advanced Structures and Composites Center, with which the company is still affiliated. Many of its early projects involved its “Bridge-in-a-Backpack” composite arches — now used in 28 bridges across the U.S. and internationally — but much of its recent focus has been on the composite girders.
The company’s 15-strong team of engineers and manufacturers has already signed on to construct another bridge in Hampden: a 55-foot composite girder bridge at the location of the Twin Bridge, which carries Route 69 over the West Branch Souadabscook Stream. Construction is expected to start in the spring.
Hampden Town Manager Paula Scott praised the Department of Transportation’s use of the composite girder technology, citing its strength and lifespan.
“This project can be an example of spending money wisely for the future,” she said.