The Cuyuna Lakes State Trail had an at-grade crossing of TH 6 in the City of Crosby. The crossing on the heavily used trail in the Cuyuna Country State Recreation Area was dangerous for pedestrians and bicyclists.

The City of Crosby partnered with the Minnesota DNR, MnDOT, and Iron Range Resources and Rehabilitation Board (IRRRB) to fund and construct a tunnel separating pedestrian and bike traffic from TH 6. This underpass represents nearly 20 years of planning and collaboration, beginning in 2000 with the formation of the Cuyuna Lakes Trail Association. A 2015 grant for $600,000 approved by the Minnesota legislature, along with collaboration between the various cities, organizations, and some private property owners helped bring this project to fruition.

Bolton & Menk provided plan development and construction assistance for the grade separation project. The bridge design and construction incorporated several notable features that make it stand out from typical precast box culvert bike and pedestrian underpasses. For example, the end treatment used form liner resembling wooden plank to give users the look and feel of entering a mine shaft, paying homage to local mining history. The result is a unique ADA-compliant underpass that pedestrians and bikers can use to enjoy a safe crossing of the busy TH 6 highway.