+ What is a Diverging Diamond Interchange (DDI)?

A Diverging Diamond Interchange (DDI) is a type of freeway interchange where motorists entering/exiting the freeway cross to the opposite side of the road as they go through an interchange. This allows for continuous movements onto the freeway ramps. Signalized high volume left-turn movements, which are a typical challenge with standard four-way interchanges, are optimized with a DDI.

+ What are the benefits of a DDI?

Diverging Diamond Interchanges (DDIs) have been shown to increase capacity and safety, reduce congestion, and minimize the cost of new infrastructure. Advantages include:

  • Improved safety by reducing the number of ways vehicles can collide (14 compared to 26 for a conventional diamond interchange).
  • Increased capacity by eliminating the left turn signal and allows traffic to flow more efficiently through the interchange.
  • Reduced delays and congestion.
  • Meeting the needs of all users (motorists, large trucks, pedestrians and bicyclists).
  • Reduced construction costs due to smaller bridges.

+ How can I learn more about the LaCrosse DDI Project?

You can:

  • Follow the project social media pages for project updates and information.
  • Attend upcoming Public Meetings on Final Design and Construction.
  • Visit the mobile display and “walk the DDI” before you drive it. A mobile display schedule of events will be posted on the project website.
  • Submit your questions to the Project Contacts via the project website.

+ When will the project be complete?

Construction is tentatively scheduled to be completed in June 2023.

+ How do I drive through a DDI?

When entering the Diverging Diamond Interchange (DDI), drivers cross over to the left side of the road, guided by signals, signs, and pavement markings. During this time, traffic functions like a one-way street and drivers make a free flowing left turn onto the freeway.

Motorists turning right do not have to stop to access the ramp and through traffic continues to a second set of traffic lights. Pedestrians travel on designated walkways and cross only at the crosswalks.

+ Did you look at other intersection options for this area?

Yes. Four alternatives were considered as part of a planning study of this interchange. The options considered included a Standard Diamond Interchange, a Single Point Interchange, a Diverging Diamond Interchange, and a do-nothing option. The DDI was the best option to:

  • Satisfy traffic needs for now and into the future
  • Maintain better traffic flow during construction
  • Have the least impact to nearby properties
  • Improve safety by having the least vehicle conflict points
  • Save money – it’s the least expensive option

+ When does construction start?

Construction is tentatively scheduled to start in February 2021.