Wisconsin Department of Transportation

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Innovative Interchange and Intersection Design

DDI, Echelon, and SPI interchanges

WisDOT is considering the use of a variety of interchange options at key highway interchanges across the state, using innovative design to help move large volumes of traffic through limited amounts of space safely and efficiently.

  • Diverging Diamond Interchange (DDI) - This innovative interchange, sometimes called a “double crossover diamond,” is designed to intuitively guide motorists through the pathways. These interchanges have been shown to increase capacity and safety, decrease congestion and minimize the cost of new infrastructure.
  • Echelon Interchange - This innovative interchange is designed to accommodate two high-volume streets. An echelon introduces a bridge, splitting traffic into two levels, creating two separated intersections of one-way streets. Because there is no opposing traffic for left turns there is more green light time for all movements.
  • Single Point Interchange (SPI) - This innovative design helps move large volumes of traffic through limited amounts of space safely and efficiently. All traffic is controlled by a single set of traffic signals located in the center of the intersection.

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Last modified: June 7, 2013

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