![Pieces of the AEWC Advanced Structures and Composite Center's "bridge in a backpack" wait to be assembled. One of the bridges, which were developed at the AEWC, recently replaced the Backstream bridge in Hermon. Another is currently being constructed in Belfast.](http://mainecampus.bangorpublishing.netdna-cdn.com/files/2010/09/AEWC1-web-975x650.jpg "Pieces of the AEWC Advanced Structures and Composite Center's "bridge in a backpack\" wait to be assembled. One of the bridges, which were developed at the AEWC, recently replaced the Backstream bridge in Hermon. Another is currently being constructed in Belfast.")
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The AEWC Advanced Structures and Composites Center at the University of Maine is impressing industry experts across the state as its “bridge in a backpack” technology is being used by the Maine Department of Transportation to construct a 48-foot bridge in Belfast.
The bridge, currently under construction on Herrick Road in Belfast, is the third of its kind to be constructed in Maine. There are contracts with the MDOT to construct three others in the state.
Officials have praised the technology as being cheaper, easier to install, longer lasting and better for the environment than traditional bridges. According to the AEWC’s website, aewc.umaine.edu, the technology possesses the capability of tripling the lifespan of a traditional bridge, which would normally last 40 to 70 years.
“It’s cost-competitive, there’s no doubt and it should last much longer than a typical steel or concrete bridge and essentially eliminate bridge maintenance,” Nate Benoit, project manager for the MDOT, said. “Right now, we’re in the process of further developing the technology, with experience, we expect to come up with more innovative ways to use the tubes and to decrease construction time.”
Benoit also said the project is starting to take shape nicely as construction continues and thus far there have been no major setbacks.
“Bridge in a backpack” technology is considered cutting-edge. It was invented by scientists at AEWC and introduced by the center’s director, Habib Dagher, in February 2009. It uses carbon fiber tubes that are inflated, shaped into arches and infused with resin before being moved into place. The tubes then are filled with concrete, producing arches that are harder than steel, yet resistant to corrosion. Finally, the arches are overlaid with a fiber-reinforced decking and buried under several feet of dirt and sand.
When an arch is deflated, it fits into a sack roughly the size of a hockey equipment bag, which is how the technology got its name.
UMaine students who were on campus last year should be familiar with the bridge-in-a-backpack technology: The failed arches that were part of Cloke Plaza’s original design were the carbon fiber tubes. AEWC funded part of the Cloke Plaza project, but its instructions for filling the tubes with concrete were not followed. The contractor filled the tubes from the bottom rather than from the top.
“The technique being used to fill the arches didn’t work the way that we wanted it to work,” Dana Humphrey, dean of the College of Engineering, told The Maine Campus (‘UMaine bridge technology collapses,’ Oct. 30, 2009).
“[Concrete] burst out the side of the cylinder because of the pressure, and that initiated a collapse of the first arch,” Humphrey said. “And then the first arch shifted a little bit, and that caused the second arch to also, basically, crack and the concrete spilled out the bottom.”
This technology has also been used in other areas of the state. The first bridge-in-a-backpack was erected in Pittsfield, Maine in 2008. The Neal Bridge is 35 feet long and spans the Tarn River.
Advanced Infrastructure Technologies in Orono is aiding in the implementation of the bridges across the state. According to a Bangor Daily News article published in February 2009, AIT was founded by original investors from the Neal Bridge project in order to further develop the bridge in a backpack technology. It is now in charge of licensing and marketing the structures for AEWC.
The bridge being built in Belfast will cost nearly $1.1 million, with the construction accounting for most of it at $837,167. The materials will cost $245,000. The bridge is expected to be complete by June 2011.
