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Quebec Street Pedestrian Underpass

Thorton, Colorado



Colorado Department of Transportation


URS Corporation


Asphalt Specialties Company


June 5, 2005

Technical Description:

  • Span: 14 ft
  • Rise: 10 ft
  • Length: 209 ft

The City of Thornton wanted to extend 120th Avenue to U.S. Highway 85 and needed to expand the roadway to accommodate vehicular traffic. The 2.8-mile project was designed to provide a vital east- to-west link from a rapidly growing Adams County to U.S. 85 and minimize environmental impact to wetlands and the floodplain.

In addition to the road expansion, the City wanted to improve pedestrian and cyclist safety at the busiest intersections along 120th Street. At Quebec Street, consulting engineer URS chose a CON/SPAN® precast arch structure for an underpass below the road. Due to the length of the structure, electrical boxes were cast into the precast arches and house the lighting to brighten up the corridor. A concrete slab was cast-in-place as a base for the CON/SPAN underpass. General contractor Asphalt Specialties Company worked closely with Contech during construction to make sure each individual arch was properly installed.

The City of Thornton earned the 2006 Regional Partnership Award presented by Adams County Economic Development, Inc. for their participation with Adams County and other cities on the 120th Avenue Extension Project.


Technical Description:

  • Span: 14 ft
  • Rise: 10 ft
  • Length: 209 ft

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