US-20 Rexburg Interchanges

State and national data clearly shows that the DDI design improves safety. For example, the number of severe accidents has significantly declined at the Chubbuck Interchange – also a DDI – since it was constructed. Reasons include:

• Left-turning traffic uses a dedicated “crossover” lane to safely turn, instead of waiting for oncoming traffic to stop.
• The design reduces the number of potential conflict points. (A traditional diamond interchange has 26 potential conflict points, while a DDI has 14.)
• The DDI design also reduces the opportunities for head-on collisions.

The Chubbuck Interchange is also a Diverging Diamond Interchange. While the Chubbuck Interchange goes over I-86, however, the two DDIs in Rexburg will be constructed under US-20. This allows ITD to use the existing highway overpasses. Keeping these structures will dramatically reduce construction costs as well as construction time.

Yes. Both interchanges will have multiple traffic signals, including signals at the northbound and southbound exit ramps into Rexburg. A signal will also be constructed at the left-turn “crossover” location at each interchange.

ITD has designed two 8-foot shared-use pathways on the north and south sides of both interchanges. In addition, each interchange will include crosswalks and pedestrians signals. The design also includes islands where pedestrians and bicycles can safely wait to finish crossing the interchange.

The City of Rexburg and ITD are working together to develop plans for landscaping at both interchanges. It is important that landscaping still allows clear lines of sight from every direction. Landscaping plans will be available at the next public meeting for review and comment.  The City of Rexburg will maintain the landscaping once the project is complete.

Each Diverging Diamond Interchange will include several directional signs for motorists. The design also includes curb and gutter to help guide motorists through the interchange. As construction gets closer, ITD will provide educational materials for drivers. More information will also be available at the next public meeting later this year.

ITD plans to begin construction in 2023. While it is still too early to know exact details about construction phasing, ITD will keep the community informed as the construction date gets closer.

Removing snow from a Diverging Diamond Interchange is no more difficult than removing snow from a traditional interchange. Snow removal at the new interchanges will continue as it does today. ITD will continue to remove snow from state and U.S. highways. The City of Rexburg will continue to be responsible for snow removal on city streets and sidewalks.