Composites are gaining popularity to build and reinforce bridges, and the University of Maine Advanced Structures and Composites Center’s Composite Arch Bridge or “bridge-in-a-backpack” design is no exception. In recent years, a handful of bridge-in-a-backpack structures have cropped up in Maine and New Hampshire, as well as two in Michigan. The most recent installations are the Wanzer Brook in Fairfield, Vt., and the first international installation in Trinidad.

A “bridge-in-a-backpack” design consists of a series of hollow FRP tubes that arch across the river below. The tubes are filled with concrete, and then construction crews lay a deck across the top. The composite shell provides a protective barrier that keeps out road salt, chemicals and moisture, which degrade conventional bridges.

This bridge design can be built in weeks instead of months, and there’s no need for trucks to bring in heavy steel beams. This not only cuts construction time and saves money, but also reduces the backlog of bridges that need replacement.

Tim Kenerson is a design engineer with Advanced Infrastructure Technologies, which spun off from the university center. He said the first bridge was installed in 2008 and hasn’t required any maintenance.

“If you think of it, there’s really nothing in our system that can corrode or degrade,” Kenerson said.

Check out Composites Manufacturing’s feature on Brit Svoboda, president of Advanced Infrastructure Technologies, Inc., after the Bridge-in-a-Backpack design won the ASCE Charles Pankow Award!