What is the Exit 16 DDI Project?

The project consists of improvements to approximately 1 mile of US Routes 2/7 in Colchester. The core of the project is the installation of Vermont’s first Diverging Diamond Interchange (DDI) where US Routes 2/7 meet the I-89 on and off ramps at Exit 16. The project will include improvements to additional intersections along US Routes 2/7 within the project limits. Turning lanes will be constructed along US Routes 2/7 at the intersections of Mountain View Drive, Hercules Drive, and Rathe Road. The existing traffic signals will be upgraded at the intersections of Tigan Street, South Park Drive, Mountain View Drive, Hercules Drive, and Rathe Road. Pedestrian and bicycle facilities such as sidewalks and shared-use paths along US Routes 2/7 will also be constructed within the project area.

Where is the Exit 16 DDI Project?

The project area extends from the Colchester-Winooski town line north along US Routes 2/7 for approximately 1 mile, just beyond the intersection of Sunderland Woods Road at US Routes 2/7 in Colchester. The project also includes traffic signal upgrades at Tigan Street in Winooski.

What is a DDI and how does it work?

A Diverging Diamond Interchange (DDI) allows traffic to cross to the left side of the roadway to ease access to the interstate and eliminate difficult left turns without increasing the number of lanes or traffic signals. For more details on DDIs, visit our What is a DDI page. A brief instructional video on the benefits and functionality of the DDI is now available on this website.

What are the benefits of the Exit 16 DDI Project?

The Exit 16 DDI Project will improve roadway conditions along US Routes 2/7 for safety and mobility. The DDI is anticipated to reduce traffic congestion and the number and severity of crashes occurring at the interchange of US Routes 2/7 and I-89. The addition of turning lanes and upgrades to the existing signals at adjacent intersections, and improvements to pedestrian and bicycle facilities throughout the project area will also help mitigate congestion and safety concerns throughout the corridor.

In addition, the DDI design allows for incorporation of the existing Interstate 89 bridges, therefore reducing the project footprint and impacts to adjacent properties. Using the existing infrastructure also dramatically decreases construction costs.

Also, the DDI’s channelizing raised islands significantly reduces the number of wrong-way entrances onto the interstate.

Where are DDIs currently in service?

The are 98 DDIs in operation globally, with the first ever constructed in 2009 in Springfield, Missouri. Currently, 121 DDIs are in advanced design or planning in the United States.

Below are just a few of the DDIs in the United States. A total of 46 states have DDIs in use or in planning.

Will the DDI cause driver confusion?

No. Roadway elements such as signing, pavement markings and barriers will assist and guide motorists through the interchange properly.

How will the DDI function during a power outage?

The traffic signals will be connected to a back-up natural gas-powered generator; in the event that the generator fails to provide enough power during the outage, motorists should treat the traffic signals as stop signs, per the law.

How long will construction take?

Construction is scheduled to begin in the Spring of 2020. The project will be completed over the course of two construction seasons and is scheduled to be completed in the Spring of 2022.

Who is the contractor?

The project is scheduled to be advertised for bid in the Fall of 2019. The contract will be awarded in the Winter of 2020.

How can I learn more about the project?

This website provides an overview of the project and is a one-stop resource for all project related materials. Please visit the Document Library to preview all public outreach and meeting materials.

Prior to construction, public meetings will be held to share project information and provide an opportunity for community discussion. Information on the Exit 16 DDI Project will also be available on VTrans social media accounts including Twitter, Facebook, Instagram, and YouTube. In addition, project news and construction updates will be emailed to those who sign-up for our email distribution list. Please submit your email to be added to the distribution list.

What can I expect during construction?

During the first construction season, scheduled to begin in the Spring of 2020, activities will consist mainly of utility relocation, ledge removal, and possibly some drainage work.

During the second construction season, scheduled to begin in the Spring of 2021, the roadwork will begin including the construction of the DDI, addition of turn lanes at the adjacent intersections, upgrades to the existing traffic signals, and construction of the pedestrian and bicycle accommodations. Lane closures and other impacts to traffic should be expected during both primary construction seasons.

During what hours can we expect construction activities?

Most construction will occur during nighttime hours, 7:00 PM - 6:00 AM. There may be some construction activity outside of the roadway that will be allowed during the day.

Attention should be paid through the project limits at all times of day.

Will the I-89 Exit 16 ramps be closed during construction?

Long term ramp closures are not anticipated at this time, but motorists should be aware that short term closures may be required depending on the construction activity.

Will there be detours during construction?

There are no detours anticipated at this time.

Will bicyclist and pedestrians be able to cross through the interchange during construction?

A temporary path designed for pedestrian and bicycle use will be constructed early in the project to minimize pedestrian/bicycle & vehicle conflicts.

How can I say informed during construction?

During construction, weekly Construction Updates will be distributed to notify the public of construction activities and travel conditions for the following week. Project Updates and Traffic Alerts will also be issued on an as needed basis throughout the life of the project. All project updates will be posted on this website.

To sign-up to receive project updates, please click here.

VTrans social media accounts, including the @511VT and the @AOTVermont Twitter pages and the @VTransontheroad Facebook page, will be used to announce major milestones.

How do I contact the Exit 16 DDI Project team?

Have a question or comment you would like to send the team? Submit a comment via the Comment Form or email us at info@Exit16DDI.vtransprojects.vermont.gov.