Lemay Avenue Realignment over Vine Drive and BNSF Railroad
Fort Collins, Colo.
Submitted By: Ames Construction
Owner: City of Fort Collins
Lead Design Firm: AECOM
General Contractor: Ames Construction
Geotechnical Engineer: CTL Thompson
Construction Engineering Consultant: Horrocks Engineers
Delivered on an accelerated schedule, the new 178-ft-long bridge supported on 13 precast pretensioned box girders alleviates long-standing congestion issues caused by the previous at-grade crossing and a nearby train switching yard. The project also included five lane miles of new roadway, 225,200 cu yd of embankment, 244,000 cu yd of reinforcing steel, more than 1,400 sq yd of rockery walls, a multiuse path with a 150-ft-long pedestrian underpass and a new intersection to accommodate a future street extension.
This is Fort Collins’ first overpass above a railroad, and the new structure shifts heavy traffic away from a historically disadvantaged neighborhood, improves response times for emergency responders and opens the door to economic and residential growth in the city’s northeastern section.
The design called for the rockery wall to be sourced from locally quarried stone and incorporated into geosynthetic reinforced-soil abutments, with galvanized mesh on the exterior providing a natural appearance. When a mining permit for the original source of embankment backfill could not be acquired in time, the project team quickly found an alternative supply source in a neighboring county. Along with helping keep the project on schedule, the replacement source material was of such high quality that it was used for road base as well.
Photo courtesy City of Fort Collins
All construction activities involving railroad infrastructure required advance planning and coordination to ensure on-track safety protection for crews and to avert disruptions to freight movement. Advanced planning was especially important to overpass substructure, superstructure and rockery wall elements that were located within 25 ft of the railroad right-of-way. Work windows or track curfews were coordinated with the railroad up to eight weeks in advance. The city of Fort Collins estimated that the overpass would save motorists 32,000 gallons of fuel a year and lower emissions. The project is registered with the Sustainable Transport Council and is on track to be certified by Greenroads, a nonprofit that advances sustainability education and initiatives for transportation infrastructure.