The existing bridges were more than 50 years old, narrow and considered structurally deficient.
Vermont’s $60 million I-91 Brattleboro Bridge Replacement Project, now in its third and final year of construction, includes replacement of four aging bridges with two new wider, modern-designed bridges.
Vermont's $60 million I-91 Brattleboro Bridge Replacement Project, now in its third and final year of construction, includes replacement of four aging bridges with two new wider, modern-designed bridges.
The design-build project is designed and managed by FIGG Bridge Engineers Inc., based in Tallahassee, Fla., with a Northeastern regional office in Exton, Pa.
The bridges are being built by general contractor PCL Civil Contractors Inc. of Tampa, Fla. for the Vermont Agency of Transportation.
Subcontractors for the project include Sebago Technics of South Portland, Maine; Golder Associates, founded in Toronto with offices throughout the United States; Hoyle, Tanner & Associates Inc. of Burlington, Vt.; Worksafe Traffic Control Industries of Barre, Vt.; Valley Crane Services Inc. of Vernon, Vt.; Rick's Vermont Steelcraft of Bellows Falls, Vt.; and Carroll Concrete Co. of Brattleboro, Vt.
The bridge replacements are considered important in terms of safety and traffic flow. The existing bridges were more than 50 years old, narrow and considered structurally deficient.
Work on the bridges is moving along well with a milder winter in the area this year. In March 2015, Vermont Agency of Transportation announced that the new bridge project was about a year behind schedule.
The winter of 2014-15 was cold and snowy.
But warmer-than-normal temperatures have kept work moving this winter.
“The bridges will open to traffic late this year,” said David Hoyne, State of Vermont director of construction and materials.
Some dismantling of existing bridges will still be going on, but it will not affect the opening of the new bridges, he said.
The New Bridges
The most critical new bridge labeled Bridge 9 will be a three-span, 1,036-ft. (315.77 m) -long arching concrete bridge over the West River built using balanced cantilever construction. Standing 100 ft. (30.5 m) above the river and scenic valley below, the 515-ft. (157 m) main span will form an open gateway anchored by curving, cathedral piers.
It will feature 10-ft. (3 m) -wide shoulders and carry two lanes of traffic each direction, northbound and southbound on I-91.
The bridge will include viewing platforms for pedestrians, hikers and visitors at the base of each pier. The piers will feature Vermont-inspired, stone-formed concrete that blends with the local environment.
Because of its viewer- and environmentally-friendly design, the crossing has been dubbed “A Bridge to Nature.”
Crews have nearly finished pier 1 on Bridge 9 and then will begin work on pier 2, Hoyne said.
The new bridge simplifies the process of crossing the West River.
“It replaces two long truss bridges and replaces it with one superstructure,” Hoyne said.
Another new bridge, known as Bridge 8 will carry the northbound and southbound lanes of I-91 over Upper Dummerston Road using NEXT beams. NEXT beams are made of steel and are an alternative to concrete box beams for 30-ft. (9.1 m) and 90-ft. (27.4 m) spans.
Consisting of a double-tee shape beam with a 13-in. (33 cm) wide tee leg, NEXT beams are considered a time- and money-saver in modern bridge construction.
Current Construction Status of New Bridges
Currently workers are casting segments of the bridge over West River with a machine called a form traveler. A segmental bridge is a concrete bridge built in short sections, one piece at a time, as opposed to traditional methods that build a bridge in very large sections.
Abutment work at the bridge over Upper Dummerston Road is complete. Girder erection was taking place in early March.
The old northbound bridge over the West River has been removed.
Most of the work on the new bridges is being done by large cranes and the form traveler, Hoyne said.
The new roadway alignment will continue through 2016.
Project Challenges
Forming and reinforcing curving cathedral piers is considered extremely complex. The effort extended the project several months past its original time frame.
The project also was slowed by permitting delays and unexpected digging difficulties.
Positive Impact of the I-91
Brattleboro Bridge Project
“We are replacing two aging fracture-critical bridges,” Hoyne said.
He pointed out that if the old bridges over the West River were to close because of a fracture, it would have a serious economic impact on the state.
The bridge provides access from the south and is considered vital for bringing goods into the state.
In addition, the new bridge over the West River will be nature/enthusiast-oriented. Its viewing platforms overlook the West River and mountainous valley below.
True to its Bridge to Nature theme, piers, viewing platforms and the railings will be complementary of the natural landscape. A Visual Quality Advisory Team consisting of Vermont Agency of Transportation, local aesthetic committee and FIGG Bridge Engineers Inc. representatives selected eco-friendly concrete stain colors, platform railing designs and other aesthetic details.
Community Impacts Including Ramp Closures
To reduce congestion, traffic personnel closed both Exit 3 on ramps from 11 a.m. to 6 p.m. on Sunday, March 6 and Sunday, March 13. Plans are to close the Exit 3 on ramps on Sunday afternoons through the end of the ski season.
The speed limit on Route 30 in the work zone has been reduced to 40 mi. (64.4 km) per hour. The route may be reduced to a single lane intermittently with flaggers regulating traffic within the work zone.
The West River Trail is open. But construction vehicles cross the trail at certain spots, so extreme caution is advised at those locations.
Trail talks will be provided for visitors in the spring.
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