Lemay Avenue CMGC

Built by Ames Construction in less than a year, the Lemay Avenue bridge over Vine Drive and the railway in Fort Collins, Colorado, alleviates traffic congestion caused by the previous at-grade crossing and nearby train switching yard. The project included the construction of a 178-foot-long bridge founded on 13 precast box girders, five lane miles of new HMA roadway, more than 1,400 square yards of rockery walls, and a multiuse path.

One month before construction began, a 150-foot-long pedestrian underpass tunnel was added to the design. This required a change in the new roadway profile, because the roadway would need to elevate over the tunnel and back down. The addition would also have implications to the embankment and groundwater. Shoring was planned to keep groundwater out during construction, but through value engineering, Ames suggested a sheet pile cofferdam to minimize groundwater infiltration. The cofferdam would serve as both a temporary construction structure and a permanent groundwater control feature, contributing to the functionality of the project. Ames devised a process to encapsulate the sheet pile with a nonporous bentonite cap to reduce groundwater infiltration, and a pumping system was designed to further contribute to a safe, dry tunnel for end users.

The rockery walls at both abutments are composed of locally quarried materials that were hand-carved and delicately placed. Open to traffic in mid-December 2021, three weeks ahead of schedule, the overpass is a signature bridge for the city, delivering on the project’s goals of neighborhood livability, congestion relief, urban design and landscaping, multimodal improvements, safety, and future development.

Learn more: City of Fort Collins