St. Vrain Greenway Longmont, Colorado
A 11.5-mile trail corridor, the St. Vrain Greenway extends from North 75th Street to Weld County Road 7 in Longmont, Colorado. The initial design included six pedestrian bridges along with trail segments adjacent to these bridges, beneath the existing vehicular bridge at Main Street (State Highway 119), and other segments where slopes or site grading was critical.
Extending a Trail Corridor While Minimizing Impact to Habitat
The initial 9.5-mile trail was followed by a two-mile segment of path designed through a riparian corridor and included a 140-foot span pedestrian bridge over St. Vrain Creek while designing for erosion control beneath the existing SH 119 bridge. Ramp connections to bike lanes along the highway, modification to an existing field access bridge, and a new pedestrian underpass structure at 119th Street and East County Line Road were also included as part of the complete St. Vrain Greenway design. Spanning from 25 to 140 feet in crossing St. Vrain Creek, Lefthand Creek, Old Dry Creek, and the Bonus Ditch, the pedestrian bridges used break-away bridge designs – from Design Concepts – in order to reduce construction costs and minimize site impacts. Several alternative path alignments were considered in the conceptual design phase to minimizing impacts to wetlands, wildlife habitat, nesting bald eagles, and other sensitive areas. Otak was involved throughout the project’s phases, from subconsultant on landscape architecture for the six pedestrian bridges to prime for the St. Vrain Greenway path design.