I-91 Bridge Replacements

Sebago Technics was a key member of the PCL/Figg Design/Build Team performing the roadway design, traffic engineering, transportation management planning, including temporary traffic control design, and environmental permitting support for this $60M construction project.

This project involved the replacement of four existing bridges on I-91 in the Town of Brattleboro with two new single structures over the West River and a local roadway. Sebago was responsible for all non-structural components of the project, including the development of the new horizontal and vertical alignments for I-91, interstate roadway and drainage design, review of river scour and hydraulic analyses by others for the proposed river bridge, environmental permitting support, landscape architecture, and maintenance of traffic.

The project was approximately 1.5 miles in length, including the two temporary crossovers on either end between Exits 2 and 3. The existing 2-barrel interstate was merged into a single 4-lane roadway for the major river crossing as a cost-saving.

One of the unique features of the Traffic Management Plan was the inclusion of a “Smart Work Zone”, which alerted drivers in advance about travel times through the “Work Zone” in real-time.

This project was notable in that it represents Vermont’s first cast-in-place concrete segmental bridge – a 1000’ long 3-span structure over the West River. This “Bridge to Nature” as it is referred to locally, has also won a number of design and construction awards: Roads & Bridges Magazine selected it the Number 1 Bridge Project in America in 2017; ACEC National named it a Grand Award Winner in their annual engineering excellence competition for 2018, and ENR New England named it their Top Bridge for 2018.

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Project Details

Figg Bridge Engineers
Brattleboro, VT
Date Completed: