Carver County staff propose uniform turn-lane policy to guide development and improve safety

Carver County staff presented a draft turn-lane warrant and design policy at a county work session, proposing consistent rules for when turn lanes should be added or modified on county highways and how long and offset lanes should be designed.

Whitney Schroeder, traffic engineer at Carver County, said the draft moves the county away from a “one-size-fits-all” reliance on MnDOT guidance and traffic operations reports and toward a policy that accounts for safety, speed and truck volumes. “We are going to be using the 20-year projected traffic volumes for a lot of the volume warrants and thresholds,” Schroeder said, and the policy uses hourly turning-movement thresholds so developers’ peak-hour analyses can be applied directly.

The policy would apply to most county projects other than simple resurfacing or seal-coat work and distinguishes uncontrolled approaches (two-way stop) from controlled intersections (signals or four-way stops). For uncontrolled intersections the draft uses speed and a relationship between turning volumes and opposing through volumes; the county would treat 50 mph and above as high-speed and 45 mph or lower as low-speed. For controlled intersections the guidance calls for capacity and crash-history review and consideration of existing lane configurations.

The draft sets several numeric thresholds and design rules cited repeatedly in the presentation: staff said they will use 20-year projected traffic for most warrants but opening-year and full-build-out volumes for developments; an ADT (average daily traffic) threshold of 6,000 vehicles per day triggers use of a Highway Capacity Manual table for some right-turn warrants; storage minimums are 50 feet where turning traffic has less than 10% heavy vehicles and 100 feet where turning truck percentages are 10% or higher; deceleration for left turns is assumed to a full stop and right-turn deceleration is assumed to 15 mph for design; and a minimum practical threshold in some subdivision examples is five turning vehicles per peak hour before a turn lane is considered warranted.

Schroeder and other staff said the county referenced professional sources in developing thresholds, including the AASHTO Green Book, the Highway Capacity Manual, the MnDOT facility design guide and various DOT policies from other states and a nearby county developing similar guidance. Drew Flummer, transportation planning manager, walked through development examples the office has already evaluated under the draft guidance (examples included a Kwik Trip site in Victoria, the High Point Vistas subdivision on County Road 61, and several aggregate pit accesses such as Mueller, Lundquist and Hanson pits). Those examples show how the warrant charts, truck percentages and speed assumptions produce different outcomes at specific intersections.

Commissioners and staff discussed process and discretion. Commissioner Puterman and others asked when individual development approvals or departure requests are brought to the board; staff said typical private-access reviews follow the county’s access policy and are processed by planning staff and the county engineer and usually do not come to the full county board unless an applicant appeals or seeks an exception. Staff noted there is an existing statutory review process for plats and preliminary plans when county highways are impacted and that, as drafted, the new turn-lane policy would allow the county engineer or designated staff (Lynette was named during discussion) to make case-by-case exceptions, with the county board available as an ultimate appeal.

Several commissioners raised implementation concerns: potential developer pushback about construction costs, the need to coordinate with cities on annexed parcels (Victoria was discussed), and funding or timing for county capital projects. Staff noted one corridor project on Highway 11 has federal funds and is expected in 2028, and they said the county would typically not require retrospective upgrades to existing accesses unless use changed beyond previously approved conditions or a documented safety issue arose. Schroeder said design is iterative and that horizontal curves, right-of-way limits and vertical geometry would sometimes require adjustments from the table values.

Staff outlined next steps: incorporate comments from the work session, circulate the draft to city and township engineers and planning staff for written comment, and present the policy to the county board for adoption in June. Schroeder said, “We plan to then share this policy with cities and townships, and then we'll be presenting this to the board for adoption in June.”

The work session included multiple staff clarifications about how the policy would be applied to development review and how exceptions and appeals would be handled; commissioners urged clear language about whether applicants can appeal staff decisions to the county board. Staff said they would add clarity on appeal procedures and continue outreach to cities and townships before final board consideration.