Interstate 94 / County Hwys. N & TT

Cottage Grove, Dane County, WI


MTJ Roundabout Engineering provided the roundabout analysis, design, peer review for 30/60/90% plans, and public outreach support to WisDOT, as a subconsultant to Ayres & Associates, for this series of three roundabouts.


This challenging roundabout project includes two interchange ramp terminal roundabouts and high-speed approaches for the CTH N/CTH TT roundabout. Key to this effort was developing a design that was sensitive to ROW impacts and business access, while allowing safe residential drives to exist to ensure safety and access for all modes of travel.

MTJ’s extensive roundabout design experience played a pivotal role in achieving the correct roundabout design solution and acceptance of this unique and controversial application of three roundabouts.


  • Commercial driveway access
  • Pedestrian/bicycle facilitation and safety
  • Large truck and freight accommodations
  • Series of three roundabouts
  • Includes two interchange ramp terminals
  • High-speed/transitional speed approaches

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