Assessment of the “Bridge in a Backpack” Bridge System from Advanced Infrastructure Technologies (AIT)

The Vermont Agency of Transportation (VTrans) installed a Bridge in a Backpack (BiaB) system, or also referred to as a Rigified Fiber Reinforced Polymer (FRP) Tube Arch (RFTA) Structure on a low volume road in a rural setting. The value of using this system is the potential to use smaller and lighter construction equipment for a restricted delivery location such as forest or farm roads. The BiaB does not require large cranes and there is a potential for in-field fabrication of the tube arch members where large truck delivery is limited. Advantages of the system include good waterway characteristics and suitability for ledge controlled or spread footings. Disadvantages of the system are that few have been constructed and that it has aesthetic limitations. The construction of the Fairfield BiaB project proceeded smoothly. Generally, site conditions and limited experience with the BiaB led to less than ideal means and methods for construction of the system. During construction, it was noted that several opportunities remain for further expedited construction and cost reduction. Generally, VTrans’ experience with the BiaB showed that the system provides a benefit to the State.