Project Announcement - Final Phase to Begin This Summer
The Exit 16 Diverging Diamond Interchange Project Team is proud to announce that the final phase of construction of the Exit 16 DDI Project is coming this summer!
DATE: Friday, May 30, 2025
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 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.
Project Phases
The project is being executed in two phases under two separate and sequential contracts.
- Phase 1 began in Winter 2023 and concluded in 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 was awarded in May 2025 to S.D. Ireland Brothers Corporation, for approximately $22.5 million. Construction is anticipated to begin later this summer and conclude in Summer 2027. This phase will focus on roadway construction, including the installation of the DDI, additional turn lanes, and pedestrian and bicycle accommodations.
What is a Diverging Diamond Interchange?
A DDI is an innovative, modern interchange design that can relieve traffic congestion and improve safety for drivers, bicyclists, and pedestrians. In a DDI, traffic crosses to the left side of the roadway, allowing traffic to make a left onto the interstate entrance ramps without crossing oncoming traffic. The reduction of conflict points eliminates potential user collisions, thus improves safety and vehicle throughput. With left turn movements operating freely within the DDI, the traffic signals no longer require protected left turn phasing, improving overall traffic operations at the interchange. Additional benefits include reducing driver discomfort, fuel consumption, and lost time. The DDI’s channelizing raised islands significantly reduce the number of wrong-way entrances onto the interstate. The raised islands also create short crossing distances, which increase overall safety for non-motorized users such as pedestrians and bicyclists.
Stay Informed
The project team will provide additional project announcements as the start of construction approaches, and weekly Construction Updates during construction. Want to join our email list to receive future project updates? Send us an email!