The Vermont Agency of Transportation is thinking outside the box to reduce the number of structurally deficient bridges in the state, utilizing a longer-lasting design that can be built quicker than traditional methods.
When the bridge over the Wanzer Brook in Fairfield needed replacement last month, the agency turned to a method dubbed “bridge in a backpack.” After taking down the existing span, crews placed a series of hollow tubes which were later filled with concrete. Once the filled tubes were in place, they began constructing a new carbon fiber composite bridge deck on top.
This innovative method is saving time and money for VTrans and the town of Fairfield, going up in weeks instead of months. The combination of composite decking material and concrete tubes will increase the durability of the 35-ft bridge, as the composite shell will protect the inner tubes from environmental conditions. In all, the bridge is designed to last at least 100 years with little maintenance. The town of Fairfield is paying $45,000 of the total $900,000 project cost.
Since the accelerated bridge program was put in place, VTrans reports that it has been able to reduce its inventory of structurally deficient bridges from more than 30% to less than 8%.
