Diverging Diamond Interchange (DDI)

WisDOT has constructed Diverging Diamond Interchanges (DDIs) at key highway interchanges across the state. This innovative interchange, sometimes called a “double crossover diamond,” is designed to intuitively guide motorists through the pathways.

Diverging diamond interchange 

These interchanges have been shown to increase capacity and safety, decrease congestion and minimize the cost of new infrastructure. The DDIs in Wisconsin are located at:

  • I-39/90 and WIS 11/Avalon Road interchange, south of Janesville
  • WIS 441 and Oneida Street interchange, Appleton
  • I-39/90 and WIS 26/Milton Avenue interchange, Janesville
  • I-39/90 and WIS 81 interchange, Beloit

Advantages of this type of interchange

  • Safety – Reduces the number of ways vehicles can collide by almost half (14 compared to 26 for a conventional diamond interchange).
  • Greater capacity and efficiency – Accommodates more traffic than conventional designs. Drivers make free-flow right and left turns on to the major freeway.
  • Easy navigation – Guides drivers with overhead signs, pavement marking, and traffic signals.
    Meets the needs of all road users – Accommodates large trucks, pedestrians and bicyclists.

Navigating a DDI

  • Drivers follow the signs, signals and pavement markings to cross through the intersection at the first set of traffic lights. Traffic appears as if on a one-way street.
  • All left turns onto the freeway are free flow, meaning vehicles do not have to stop to access the ramp.
  • Vehicles going straight simply proceed through a second set of traffic lights.
  • Pedestrians travel on designated walkways and cross only at the crosswalks.
  • Bicyclists may choose to use the bike lane or pedestrian walkways and crosswalks.

WisDOT is committed to exploring all available options for safely and efficiently moving traffic. Using the latest engineering technology and techniques gives us more options than simply adding lanes. The economic benefits combined with improved safety and mobility will contribute to enhanced competitiveness and quality of life for businesses and communities. Where appropriate, we will incorporate these innovative designs into future interchanges.

Additional videos

I-39/90 and WIS 26 DDI, Janesville video (04:25) Youtube logo - Drive-through animation and benefits of DDI to all road users

North Carolina DDI video (02:52) Youtube logo - Good overview of a DDI interchange.

Missouri DDI video (01:12) Youtube logo - A driver’s experience traveling through a DDI.