Single Point Interchange (SPI)

WisDOT is considering the use of SPIs at key highway interchanges across the state. This innovative design helps move large volumes of traffic through limited amounts of space safely and efficiently.

Single Point Interchange 

All traffic is controlled by a single set of traffic signals located in the center of the intersection. An SPI is currently in place at the US 12/US 53 interchange in Eau Claire (image above).

Reasons for considering this interchange type

  • Safety – Reduces the ways vehicles can collide by one third (18 compared to 26 for a conventional diamond interchange).
  • Greater capacity and efficiency – Accommodates more traffic than conventional designs.
  • Accommodates large trucks.
  • Easy Navigation – Guides drivers with overhead signs, pavement marking, and traffic signals.

Navigating an SPI

  • Drivers follow the signs and pavement markings to the traffic signal.
  • The intersection operates like a traditional intersection.

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.