Dakota County presents three options to address crashes at County Road 50 and 185th double roundabout

Dakota County transportation staff told the Lakeville City Council on July 6 that the County Road 50 and 185th Street double roundabout has been the county's highest crash location for years and that current crash volumes and some serious injuries justify further study. Erin Labrie, Dakota County transportation director, introduced traffic engineer Tyler Craig, who said the intersection's crash-rate index is roughly 5.96, well above the threshold of 1.0 used to flag trouble spots.

The county presented three conceptual options: (1) enhanced roundabout improvements such as permanent buffered lanes, pedestrian beacons and rumble/mumble strips; (2) the same improvements plus southbound and eastbound right-turn bypass lanes to remove turning traffic from the roundabout's circulating lanes; and (3) converting the intersection back to a signalized junction. Craig said the county also audited every crash in a 2024 deep dive, ran design peer reviews and performed traffic control analyses to compare safety, delay and cost implications.

Craig described trade-offs. Roundabouts historically reduce crash severity but can show higher total crash counts when volumes are large; county data show both crash counts and severity have risen since the roundabout opened. The bypass option reduces internal roundabout volume but may introduce new conflict points for turning vehicles and pedestrians. Signalization offers more precise control of movements and timing flexibility but, the presenters said, can create substantially greater delay for motorists and require a larger footprint or different phasing to function.

County staff displayed operational modeling that projects travel delays over future growth scenarios. Under a high-growth case the enhanced-roundabout option showed increasing delay over time; the bypass option extended the road's effective operating horizon; and the signal option remained more sustainable across some growth scenarios but at the cost of longer delays. The county reported current peak-day entering volumes around 47,000 vehicles per day on the intersection approaches and said some comparable 2x2 roundabouts nationwide experience similar problems when entering volumes exceed roughly 50,000 vehicles.

Council members pressed the county on specifics: which movements account for the majority of crashes, whether drivers are diverting onto neighborhood streets, how proposed changes affect pedestrians and snow removal, and whether possible future projects such as a Kenrick connection would materially change traffic patterns. Craig said the 2011 Kenrick analysis suggested at most a few thousand vehicles per day could shift off the roundabout, not enough by itself to eliminate the crash problem.

Labrie and Craig said the next step is returning to the Dakota County Board with meeting feedback and a request to fund preliminary engineering and a consultant contract to develop 30% design layouts, conduct additional traffic modeling and expand public engagement. "Our main goal of this whole analysis has been crash reduction," Labrie said. "Delay is secondary." Craig added that some low-cost, near-term measures such as permanent mumble strips and clarified striping would be pursued while the county seeks direction on larger investments.

The county asked councilmembers to provide feedback before the county board meets next week; no formal local vote on design choices was requested at the meeting.