Mr Habib Dagher, director of the University of Maine-based Advanced Engineered Wood Composites Center, offers comparable construction costs, reduced maintenance, shorter build schedules, and less harmful impacts to the environment.
One of the nation’s greatest challenges is how to effectively address the problems resulting from our aging transportation infrastructure. Last year, the American Society of Civil Engineers (ASCE), Reston, Va., updated its 2005 “Report Card for
America’s Infrastructure” presenting the country’s bridges with an overall grade of C. The report stated that more than 26% of the nation’s 600,000 bridges are either structurally deficient, meaning they could be closed or restrict traffic due to limited structural capacity, or functionally obsolete, meaning they cannot accommodate current traffic volumes, vehicle sizes, and weights.
According to the U.S. Department of Transportation’s 2006 Conditions and Performance Report, $8.7 billion in annual capital investment is needed to maintain bridge conditions at current levels, while another $12.4 billion would be needed to actually improve conditions to a level that would help relieve congestion and reduce accidents.
Individuals from the University of Maine, Orono, Maine; the Maine Department of Transportation (MaineDOT); and Advanced Infrastructure Technologies, Orono, Maine, believe they have a technology that could play a role in alleviating some of the country’s transportation infrastructure needs. The technology is known as a bridge-in-a-backpack and was used for the first time in the country to construct the 34-foot-long Neal Bridge in Pittsfield, Maine, and the 28-foot-long McGee Bridge in North Anson, Maine. MaineDOT also is currently building five new bridges using the technology, with the first being the 38-foot-long Royal River Bridge in Auburn, Maine.
The technology received its name from the portability of its materials. According to creator Habib Dagher, director of the University of Maine-based Advanced Engineered Wood Composites Center, the fiber-reinforced polymer (composite) tubes that form the structural spine of the bridge could fit inside a backpack. When compared with traditional concrete and steel projects, the bridge-in-a-backpack technology offers comparable construction costs, reduced maintenance, shorter build schedules, and less harmful impacts to the environment.
How it works
The composite tubes, typically 12 inches in diameter, are inflated and formed into
arches. Using a vacuum pump, the tubes are treated with an epoxy resin, causing them to stiffen into shape. Then the tubes are installed spaced apart—in the case of the Royal River Bridge, 13 were needed—and filled with concrete. Covered with a composite deck form topped with concrete and compacted soil, the tubes can support a standard gravel-and-asphalt roadway.