THE CONCRETE BRIDGE MAGAZINE

WINTER 2018

ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.

Issue link: http://www.aspiremagazinebyengineers.com/i/922349

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The existing causeway along with the temporary trestles served as a working platform during construction. Note the difference in the new and old roadway elevations. Construction of the Interstate 91 (I-91) Brattleboro Bridge Project in Brattleboro, Vt., replaced twin existing bridges over the West River with a new long-span landmark bridge. The best value-selected, design-build project was designed by the team for the Vermont Agency of Transportation (VTrans). The new gateway bridge features a 1036-ft-long arching concrete bridge soaring 90 ft above the West River and built using balanced-cantilever construction. Two piers flank the river banks to support the three-span (263- 515-258 ft) bridge. Vermont's Bridge to Nature It was important to VTrans and the surrounding communities that the new bridge serve as an icon and a gateway to Vermont. The bridge construction also needed to have minimal impact on the traveling public using the bridge, as well as those traveling under the bridge: vehicles on Vermont Route 30 (VT 30) (a major route for ski resorts), kayakers on the beautiful West River, and hikers on the West River Trail. The design-build team was excited about the challenge of designing and constructing a beautiful, signature structure that represents Vermont. O v e r l o o k i n g t h e We s t R i v e r a n d mountainous valley, this bridge features viewing platforms for pedestrians, hikers, and visitors. True to its theme, "A Bridge to Nature," every detail of the uniquely shaped superstructure, including its piers, viewing platforms, and railings, complements Vermont's natural landscape. The piers feature Ve r m o n t - i n s p i r e d s t o n e - f o r m e d and stained concrete that blends with the local environment. A visual quality advisory team consisting of representatives from VTrans, the local aesthetic committee, and the bridge designer selected eco-friendly concrete stain colors, platform railing designs, and other aesthetic details. The focal points of the bridge are the quad-wall piers, which emerge from the ground in sweeping organic forms and support the arching concrete spans. Each quad-wall pier is comprised of four concrete columns that individually curve outward in two directions, creating a symmetrical patter n. The three- dimensional (3-D) design and detailing of the columns resulted in a varying cross section and complex reinforcing steel configurations. The designer, contractor, reinforcing steel fabricator, and formwork provider held workshops to ensure that all details were considered and to provide the most efficient design. The quad-wall system of the piers provides stability, and allowed the bridge superstructure to be built from above using balanced-cantilever s e g m e n t a l c o n s t r u c t i o n w i t h o u t temporary falsework in the river. This scheme minimized the impact of the project on the West River and West River Trail. profile INTERSTATE 91 BRATTLEBORO BRIDGE / BRATTLEBORO, VERMONT BRIDGE DESIGN ENGINEER: FIGG Bridge Engineers Inc., Exton, Pa. ROADWAY/GENERAL CIVIL ENGINEER: Sebago Technics Inc., South Portland, Maine PRIME CONTRACTOR: PCL Civil Constructors Inc., Raleigh, N.C. POST-TENSIONING CONTRACTOR: DSI, Freedom, Pa. INTERSTATE 91 BRATTLEBORO BRIDGE— A GATEWAY TO NATURE IN CONCRETE by Garrett Hoffman, FIGG Every detail of the uniquely shaped superstructure complements the natural Vermont landscape. Each quad-wall pier is comprised of four concrete columns that curve outward in two directions, symbolizing stone trees emerging from the ground and supporting the arching concrete spans. All Photos: FIGG. 22 | ASPIRE Winter 2018 P R O J E C T

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