Underpass will connect Four Mile Creek Trail with Cottonwood and LoBo trails 

Boulder County, Colo. - The Public Works and Community Planning & Permitting departments will begin the final phase of the Four Mile Creek Trail underpass project next Monday, Oct. 28.  The nearby Cottonwood Trail and Four Mile Canyon Creek Path northeast of Boulder will remain open as long as possible during construction, but trail closures may be needed to complete the final connections. Please visit OSMPTrails.org to see current trail closures across city-managed trails, including sections of the Longmont-to-Boulder (LoBo) Trail that may be closed during the project.  

It is imperative that people do not trespass through the construction site or full trail closures may be enforced to protect public safety. Trespassing could also result in a municipal summons and fines. View a map of the construction area.  

BNSF recently finished their work on railway infrastructure that will allow for the underpass’ completions. The County’s work will also include the pathway connection and landscape restoration. Work is expected to last through December, weather permitting.  When complete, 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. For more information, visit the project webpage, or contact Andrew Barth, Public Works Communications, at abarth@bouldercounty.gov or call 303-441-1032.