McMillan and Black Cat Roundabout

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The Ada County Highway District (ACHD) is designing a future roundabout for the McMillan and Black Cat intersection. The purpose of the project is to improve traffic flow and increase safety for all users.

Proposed Improvements

  • Construct a multi-lane roundabout at the McMillan and Black Cat intersection
  • Add curb, gutter and a detached 10-foot-wide multi-use pathway
  • Construct crosswalks at each leg of the intersection with two-stage pedestrian crossings
  • Install rectangular rapid flashing beacons (RRFBs) at each pedestrian crossing
  • Add a truck apron for larger vehicles to use if necessary and intersection lighting


The Ada County Highway District (ACHD) is designing a future roundabout for the McMillan and Black Cat intersection. The purpose of the project is to improve traffic flow and increase safety for all users.

Proposed Improvements

  • Construct a multi-lane roundabout at the McMillan and Black Cat intersection
  • Add curb, gutter and a detached 10-foot-wide multi-use pathway
  • Construct crosswalks at each leg of the intersection with two-stage pedestrian crossings
  • Install rectangular rapid flashing beacons (RRFBs) at each pedestrian crossing
  • Add a truck apron for larger vehicles to use if necessary and intersection lighting


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    What do you think?

    After reviewing the information for the McMillan and Black Cat project, please take a moment to fill out the community feedback survey.

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Page last updated: 10 Aug 2026, 01:56 PM