I-91 Bridge Replacement in Brattleboro, Vermont
SEGMENTS, SPRING 2016, VOL. 60
Cantilever Construction Speeds Through The Winter
The I-91 Brattleboro Bridge Improvement Project located in Brattleboro, Vermont includes the replacement of four bridges with two new bridges, called Bridges 8 & 9. This design/build project is designed by FIGG and built by PCL Civil Constructors, Inc. for the Vermont Agency of Transportation (VTrans). At $60 million, this project is VTrans’ largest bridge project to date. The centerpiece of the project is Bridge 9, a new three-span, 1,036-foot arching concrete bridge over the West River. It is being built using cast-in-place balanced cantilever construction techniques. Standing 100 feet above the scenic valley, the Bridge 9’s graceful 515-foot main span will form an open gateway anchored by curving, open twin wall piers. When complete, this postcard-worthy bridge will provide a unique experience to drivers and sightseers in this beautiful valley. It will feature viewing platforms at the base of each pier overlooking the West River and surrounding mountains. The piers will feature Vermont-inspired, stone-formed concrete that compliments its environment. The concrete cantilever construction process is the most sustainable, environmentally-friendly and mobility-maximizing method for this project. It avoids impacts to Vermont’s busy Route 30, the West River, and popular West River Trail. PCL Civil Constructors, Inc. is nearing completion on the Pier 1 cantilever segments using cast-in-place construction and form travelers. To continue casting through the winter, the form travelers were enclosed with a custom-made tarp system and the exterior forms were insulated. Glycol heater hoses and forced air heaters were used to ensure the forms and the enclosure were above specified temperatures for pouring and curing segments. The enclosure and heating system allowed segments to be poured with outside temperatures as low as 15 degrees Fahrenheit. The segments are 104'-8" wide, 14'-8" to 16'-0" long and vary in height from 26'-11" at the pier table to 12'-7" at mid-span. Pier Table 2 construction was recently completed with the last lift poured in January.
The 104'-8" wide, 30'-7" tall and 56'-0" long pier table was poured in five different lifts using EFCO form systems. In March, the forms and falsework were lowered to the ground for disassembly using a DSI strand jack system. Form travelers will be disassembled and transported to Pier 2 this spring for segment construction this summer and fall. The bridge is scheduled to be complete this coming winter.