Project Announcement - Exit 16 DDI to become Operational in mid-September
Major Milestone: Traffic Changes Coming as the Exit 16 Diverging Diamond Interchange Opens This September
DATE: Wednesday, August 26, 2026
The Vermont Agency of Transportation (AOT) is improving the roadway along the U.S. Route 2/7 (U.S. 2/7) corridor, in the vicinity of Interstate 89 (I-89) Exit 16, to enhance mobility and safety in Colchester, Vermont. The project area extends from the Colchester-Winooski town line north for approximately 1 mile to just beyond Sunderland Woods Road. The core of the project is to reconfigure the existing tight diamond interchange into a Diverging Diamond Interchange (DDI) at I-89 Exit 16.
The final construction phase of the project, which includes the construction of the Diverging Diamond Interchange and other multimodal transportation improvements, began in May of 2025, and will be completed in July of 2027. This September will mark another major milestone as the new traffic pattern is implemented and the Diverging Diamond Interchange becomes functional. Supplemental updates will be issued in the coming weeks.
Test Drive the DDI at the Champlain Valley Fair
With new traffic patterns coming to the Exit 16 Interchange this September, the Exit 16 DDI Project Team is ramping up community outreach efforts!
Join us at the Champlain Valley Fair from August 28 through September 6, where project team members will be available to answer questions, provide updates, and address concerns about the upcoming traffic changes. Visitors can also take a turn on our driving simulator and experience the future interchange before the new traffic pattern is implemented in September.
Be sure to stop by for project information, giveaways, and other fun promotional items. We will be located in the North Expo of the Robert E Miller Expo Centre. We look forward to seeing you there!
What is a Diverging Diamond Interchange?
A Diverging Diamond Interchange, or DDI, is an innovative, modern interchange design that can relieve traffic congestion and improve safety for drivers, bicyclists, and pedestrians.
How it works
In a DDI, vehicles briefly cross to the left side of the road as they travel through the interchange. This allows drivers making a left turn onto interstate entrance ramps to do so without crossing oncoming traffic. After passing through the interchange, traffic returns to the normal right side of the roadway.
Key Benefits
- Improves safety by reducing conflict points where vehicles can collide.
- Reduces congestion because left-turning vehicles move more freely.
- Increases traffic throughput by allowing traffic signals to operate more efficiently and eliminating the need for protected left-turn signal phases.
- Lowers fuel consumption and delays by reducing time spent waiting at signals.
- Reduces wrong-way highway entries through the use of raised channelizing islands.
- Enhances pedestrian and bicycle safety with shorter crossing distances and clearly defined travel paths.
A DDI temporarily shifts traffic to the opposite side of the road so left turns onto interstate ramps can occur without crossing oncoming traffic. This creates a safer, more efficient interchange that moves more vehicles through the area with fewer delays.
Project Phases
The project is being executed in two phases under two separate and sequential construction contracts.
- Phase 1 – Winter 2023 to Fall 2023: This phase involved utility upgrades and relocations, ledge removal, construction of retaining walls for future pedestrian and bicycle accommodations, and installation of drainage infrastructure. The work was completed by S.D. Ireland Brothers Corporation for approximately $7.5 million.
- Phase 2 – Summer 2025 to Summer 2027: This phase will focus on roadway construction, including the installation of the DDI, additional turn lanes, and pedestrian and bicycle accommodations. The contract was awarded in May 2025 to S.D. Ireland Brothers Corporation, for approximately $22.5 million.
Phase 2 Schedule
The remaining schedule for Phase 2:
- Early-mid September 2026 – New Traffic Pattern at Exit 16 Interchange
- Early October 2026 – Bridge Rehabilitation
- October 2026 – Construct Concrete Islands and Install Guardrail and Barrier
- December 2026 – Early Spring 2027 – Winter Shutdown
- Spring 2027 – Landscaping and Sign Installation, General Clean Up, and Demobilization
- July 2027 – Project Completion
For More Information and Resources
Visit the project website. There, you’ll find a detailed project overview, interactive map of the project limits, educational resources on how to navigate a DDI, and answers to frequently asked questions in the project’s FAQs section.
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