Trail News - Four-Mile BNSF underpass a boon for bikers

A request for $997,785 in funding for the Boulder County Public Works Four-Mile BNSF Underpass Construction Project was approved at the Boulder County Commissioners meeting last week. The underpass is part of the Four-Mile Creek Bikeway Project and will connect the Cottonwood Trail to the Four-Mile Creek Trail.

With this approval, the project has been assigned to Coal Creek Excavation which is slated to break ground in late August to early September. Construction is estimated to be on-going through the end of 2024 although a stated goal on the project website aims for completion no later than fall of 2024.

This project represents, for the first time, a way for Niwot and Gunbarrel bikers using the LoBo to Cottonwood Trails to avoid having either to ride along Highway 119 with traffic after making a dangerous surface crossing, carrying their bike across the train tracks from the Cottonwood Trail to access the Highway 119 underpass at Four-Mile Creek (which involves trespassing on railroad property), or riding further south on the Cottonwood Trail to the Boulder White Rock Ditch Trail, then doubling back to the Wonderland Trail to access the underpass at Foothills Highway.

According to the Boulder County press release, the "Four-Mile Creek Bikeway project will create a continuous, safe bikeway along SH 119 between Boulder, Gunbarrel, Niwot and Longmont."

This project is being executed in two phases. Phase I, concluded in December of 2023, consisted of the construction of railroad infrastructure which was performed by the railroad company, BNSF, in addition to the construction of a connection between the eastern end of the Four-Mile Creek multi-use trail and the northbound lanes of Highway 119.

It is the Phase II portion of this project which just last week was approved for funding by the county. Phase II represents the creation of the underpass below the BNSF railroad track that will connect the Four-Mile Creek Trail to the Cottonwood Trail. The funding for these projects was obtained by combining a 2007 federal transportation grant with a trail implementation fund that has been approved in multiple years by Boulder County voters, most recently in 2024.

The public is specifically being warned not to enter the construction site until Phase II has been completed. Disregarding Boulder County or OSMP trail closures can result in a fine of over $2600. In addition, trespassing on BNSF property may result in a separate fine or even a court summons. Most of all, it is unsafe.

While this project represents a huge uplift in safety and function for Boulder County bikers, those who are familiar with the LoBo Trail from Niwot to the Cottonwood Trail south of Jay Road are aware that there are several discontinuities in the system that remain to be addressed. One gap which creates the most safety issues is the requirement to ride along busy 63rd Street or Spine Road areas, which also necessitates accessing and crossing Jay Road, a major thoroughfare.

However, there is a project plan underway to address these issues as well. Look for an update in the next Trail News.