Interstate 89 (I-89) is a north-south highway that runs through Vermont and New Hampshire, ending at the Canadian border. It serves as a major route for accessing Burlington, Montpelier, and the northern part of Vermont, and provides a connection to the Canadian province of Quebec.
Colchester, Vermont, is a large town on the eastern shore of Lake Champlain. One of the state's most populous towns, Colchester borders the city of Burlington and is part of its metropolitan area.
The Vermont Agency of Transportation (VTrans) is improving the interchange at Interstate 89 Exit 17 and the Chimney Corner intersection of U.S. Route 2 (U.S. 2) and U.S. Route 7 (U.S. 7) in Colchester. The Colchester Exit 17 Project will enhance safety and mobility, as well as address inefficiencies in traffic patterns at the intersection. It was developed in part to address safety concerns due to the deteriorating condition of the U.S. Route 2 Bridge over I-89, which has been replaced as a primary component of the project.
Construction on the Exit 17 project began in the spring of 2024, with a scheduled completion date in the summer of 2026. In addition to the new bridge, the project includes major improvements to the Exit 17 interchange and Chimney Corner intersection, including:
- Extending the deceleration lane of the I-89 northbound off-ramp and widening the I-89 northbound off-ramp to include two lanes onto U.S. 2 westbound and two lanes onto U.S. 2 eastbound
- Modifying the intersection of the I-89 northbound off-ramp at U.S. 2, including adding a U.S. 2 eastbound left-turn-only lane to increase capacity and reduce queuing and backups
- Reconstructing the I-89 southbound on-ramp to allow for the construction of a new southbound on-ramp for U.S. 2 westbound, thus eliminating the left-turn conflict point for this movement, reducing queuing and backups
- Constructing a new I-89 southbound off-ramp to increase distance between the I-89 southbound and northbound ramp intersections with U.S. 2
- Widening U.S. 2 eastbound and U.S. 7 northbound to accommodate additional turning lanes at the Chimney Corner intersection, to address queuing and delays
- Installing new coordinated traffic signals at these intersections for optimization and progression
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“The Exit 17 interchange and Chimney Corner intersection links three major arteries that drive mobility across Chittenden, Franklin, and Grand Isle counties,” said Patti Coburn, VTrans Project Manager. “The Exit 17 interchange provides critical interstate access to Interstate 89 for local traffic, enabling residents and businesses in the growing Chittenden and Franklin counties to utilize the interstate, eliminating extended commute times on local routes.
“U.S. 2 serves as one of only two roadways crossing Lake Champlain into Grand Isle County and carries the Lake Champlain Bikeway, a 381-mile international cycling route. It also functions as the primary route to the ferry terminal that connects Grand Isle, Vermont, to Plattsburgh, New York, making it a vital link for both regional travel and tourism. U.S. 7 provides access to I-89 for the expanding communities of Milton and western Colchester, both semi-rural areas experiencing increased residential and industrial development.”
According to Coburn, the Chimney Corner three-way signalized intersection experiences high traffic volumes, especially during the a.m. and p.m. peak periods, driven by commuter traffic from Milton, Colchester, and Grand Isle County traveling to and from the Greater Burlington area.
“The intersection has reached maximum capacity due to continued growth in these communities, resulting in congestion and traffic backups from the increased number of vehicles traveling this corridor,” Coburn said. “Traffic volumes have surpassed the capacity of the existing roadway configuration, which includes three consecutive signalized intersections on U.S. 2 with limited single-lane queue lengths between them. During peak travel periods, significant congestion occurs, resulting in extended delays and safety concerns due to high-speed vehicles on I-89 approaching areas of stopped or slow-moving traffic near the Exit 17 interchange.
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“The project improvements are paving the way for steady growth in the region. By 2035, the number of households in the service area is expected to rise by 40 percent, with job growth projected to surge by 96 percent, driven largely by expansion in Milton’s light industrial zone located just north of the interchange. With traffic volumes expected to rise by as much as 27 percent along the key corridors, these infrastructure upgrades will play a critical role in supporting future development, reducing congestion, and improving mobility for residents and businesses.”
The existing U.S. 2 bridge over I-89, originally built in 1964, was a four-span rolled steel beam bridge.
“The structure was in poor condition with widespread deterioration along the superstructure and substructure, which led to its full replacement as part of the Colchester Exit 17 Project,” said Chris Lavalette, VTrans Resident Engineer. “The existing bridge provided a vital route to the Champlain Islands in Grand Isle County and a critical connection to the interstate. To maintain these necessary connections, the project included the construction of a new bridge off the existing alignment and adjacent to the existing bridge. This allowed traffic to be maintained over the existing bridge while the new bridge was constructed. The new bridge was opened to traffic in late August 2025.”
VTrans is both owner and engineer for the Exit 17 project. The general contractor is Kubricky-Jointa Lime LLC, of Wilton, New York, and the designer is VHB of Winooski, Vermont. The contract for the approximately $26.9 million project was awarded in February 2024, and construction began in the spring of 2024. The project is 100 percent funded by U.S. Department of TransportationFederal Highway Administration programs.
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The project was structured to be constructed over three seasons. According to Coburn, the first construction season kicked off with crews mobilizing to the site and preparing the corridor for major upgrades.
“Between May and December 2024, U.S. 2 and 7 were widened, the existing I-89 southbound off-ramp was removed, and a new off-ramp and deceleration lane were constructed,” Coburn said. “Work also began on the new I-89 southbound on-ramp from U.S. 2, along with the installation of a gravel wetland. One of the more complex undertakings during the 2024 season was the construction of the substructure for the new U.S. 2 bridge over I-89, which included pile driving, geotechnical work, abutment and pier construction, and the placement of structural steel girders.
“After a winter pause, construction resumed in March 2025 with a focus on completing the bridge this year. Crews poured the concrete deck, installed approach slabs, and realigned U.S. 2 to connect with the new structure. On August 21, 2025, the new bridge officially opened to traffic. Shortly after, the existing U.S. 2 bridge was demolished and removed.”
The 2025 construction season has also seen extensive roadway improvements. Crews reconstructed the I-89 northbound ramps, completed the new southbound on-ramp from U.S. 2 westbound, and installed modernized traffic signals at key intersections. Additional upgrades included rebuilding the northbound deceleration lane, constructing a new southbound acceleration lane, and removing the existing southbound on-ramp from U.S. 2 westbound.
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As of fall 2025, Lavalette said that the Colchester Exit 17 Project has reached several additional major milestones.
“Crews have completed and opened the new I-89 southbound off- and on-ramps,” he said. “At the Chimney Corner intersection, U.S. Routes 2 and 7 have been widened to better accommodate peak-hour volumes and support future growth. The project continues to make steady progress. Construction crews are working on improvements to the I-89 northbound ramps and installing new traffic signals at key U.S. 2 intersections.
“Additional work includes building the new southbound acceleration and northbound deceleration lanes, as well as final paving and line striping throughout the corridor. With crews working ahead of schedule, major construction activities are anticipated to be completed by the end of the 2025 construction season.”
New to VTrans was the use of ultra-lightweight foamed glass aggregate (ULFGA) to provide decreased loading on compressible soils.
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“The identified geology, soil, and bedrock conditions made for interesting geotechnical design,” Lavalette said. “Bedrock was approximately 30 feet deep at the western bridge abutment and sloped downward to approximately 80 feet deep at the eastern bridge abutment, and still deeper below the eastern approach embankment. The central and eastern portion of the site had between 60 feet and 90 feet of low strength, and high compressibility glacial clays.
“The ultimate design included bridge abutments where H-piles were driven to bedrock with mechanically stabilized earth [MSE] walls parallel to the abutment face and for the wingwalls. The eastern MSE walls used conventional fill materials, but the western abutment MSE walls required ULFGA and greater-than-typical length reinforcement to accommodate bearing issues.
“Additionally, a 300-foot length of the eastern approach embankment required the use of a combination of ULFGA and conventional fill to limit the potential for global stability failures in the underlying clays at depths where traditional ground improvement methods were not available.”
Throughout the course of the Exit 17 project construction, maintaining mobility and minimizing disruption have been top priorities. Given that the existing infrastructure was already operating at or above capacity, even minor traffic interruptions had the potential to cause significant delays and exacerbate congestion.
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To mitigate these impacts, most construction activities were carried out under shoulder closures, lane shifts, and single-lane closures. Two-way traffic has been preserved as much as possible on U.S. 2 and U.S. 7, by implementing temporary and permanent roadway widening to accommodate lane shifts and preserve the existing number of travel lanes in each direction.
Periods of alternating one-way flow controlled by flaggers was limited to off-peak hours to reduce impacts on commuters. On I-89, single-lane closures were also restricted to off-peak windows. For the construction and demolition of the U.S. 2 bridges over I-89 and construction of the Exit 17 ramps, a limited number of full I-89 closures and Exit 17 ramp closures were necessary. These closures were scheduled overnight.
A smart work zone system was implemented to monitor real-time traffic conditions, including travel times, delays, and queue lengths at critical points. This data-driven approach allowed the contractor and VTrans to adjust traffic management strategies as needed, keeping motorists informed and the corridor moving.
A major challenge was the phased construction of the new U.S. Route 2 bridge and roadway alignment over Interstate 89.
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“To maintain continuous traffic flow on U.S. 2, the new infrastructure was built adjacent to the existing bridge and roadway,” Lavalette said. “Construction was further complicated by grade differences — as the new bridge was elevated above the existing alignment — and by the close proximity of the work zone to active traffic lanes. Despite these constraints, the project team successfully maintained mobility through the corridor while operating within a heavily traveled and spatially limited environment.”
- Owner/Engineer: Vermont Agency of Transportation, Barre, Vermont
- General Contractor: Kubricky-Jointa Lime, LLC, Wilton, New York
- Designer: VHB, Winooski, Vermont
- Public Involvement Services: WSP USA, Boston, Massachusetts
- Other Contractors: American Flagging Inc., Waters Excavation Inc., Frank W. Whitcomb Construction Corp., Delta Electric Company Inc., L and D Safety Marking Corporation, F. R. Lafayette Inc., Electric Light Company Inc., Geostabilization International LLC, United Steel Installers LLC, Granite State Curb Setters Inc., D.A. Collins Construction Company Inc., Geocomp Inc., Seaboard Drilling LLC, Maine Drilling and Blasting Inc., Precision Trenchless LLC, CCS Constructors Inc., Ralph A Darrah Welding, Nicom Coatings LLC, A and K Slip Forming Inc., L.M. Sessler Excavating and Wrecking Inc., Penhall Company, F.R. Lafayette Inc., Engineers Construction Inc. Photos courtesy of Vermont Agency of Transportation
