Oct. 19, 2023 - Map link correction. This is the correct link to the area map.

Boulder County, Colo. - BNSF Railway will begin their portion of Boulder County’s Fourmile Creek Trail underpass project on Monday, Oct. 23. The nearby Cottonwood Trail and Fourmile Canyon Creek Path northeast of Boulder will remain open during construction, but it is imperative that people do not trespass on the construction site or trail closures may be enforced to protect public safety. View a map of the construction area.  

After BNSF finishes their work on railway underpass infrastructure, Boulder County will begin the final phase, which includes the actual pathway connection connection. When completed in 2024, this underpass will wrap up a multi-year project that helps bicyclists and pedestrians navigate between Gunbarrel and the City of Boulder. It also will be a valuable link for people seeking to access the county’s Longmont-to-Boulder (LoBo) Trail network. 

This county effort is being completed in cooperation with BNSF, and the City of Boulder’s Transportation and Mobility and Open Space and Mountain Parks (OSMP) departments. The project is being paid for through a dedicated fund for trail implementation that was established by voters in 2007 and extended in 2022. 

For more information, visit the project webpage, or contact Andrew Barth, Public Works Communication Manager, at abarth@bouldercounty.gov or call 303-441-1032.