Pecos Street Bridge over I-70 Replacement
Wilson & Company served as the Colorado Department of Transportation’s (CDOT) lead consultant for the Construction Manager/General Contractor (CMGC) delivery and Accelerated Bridge Construction (ABC) project. This project located in Denver, CO, reconstructed the Pecos Street Bridge over I-70 and the interchange into a diamond configuration incorporating 2-lane modern roundabouts at the ramp intersections with Pecos Street.
To minimize delays to the daily 130,000 vehicles using I-70 through the interchange, CDOT decided to use ABC bridge “roll-in” technology. The project received federal “Highways for Life” funding with the ABC commitment to, as stated by U.S. Secretary of Transportation Ray LaHood, “…allow the bridge to be put in place all at once over a 50-hour period, instead of disrupting traffic over twelve months.”
The complexity and associated risks of rolling a five-million-pound bridge structure into place on I-70 over a weekend ideally suited the project for CMGC delivery, where the owner, contractor, and designer develop a collaborative relationship during the design phase of the project. Using CMGC delivery, CDOT and Wilson & Company were able to integrate the contractor’s methods and means into the project design to provide the most innovative solution to address the project’s complexity and reduce construction risks. The CDOT/Wilson & Company team developed a quality-based RFP to select the contractor for the project prior to advancing the design beyond the preliminary phase. Proposal and interview evaluations resulted in Kiewit Infrastructure being selected as the contractor for the project.
CDOT, Wilson & Company, and Kiewit worked together to advance the project design with an emphasis on the detailed design of the complex bridge. The design included the permanent bridge along with associated temporary structures necessary to construct the structure off-site in a bridge farm, and then move the bridge into its permanent location. To accommodate the roundabout intersections, the 156-ft long single-span bridge was an hourglass-shaped structure requiring a cast-in-place, post-tensioned concrete superstructure. Utilizing both transverse and longitudinal post-tensioning the bridge included more than 19 miles of post-tensioning strands.
During the weekend closure, the existing Pecos Street Bridge was demolished, and replaced with the new bridge. The roll-in moved the new structure from the bridge farm to the middle of I-70, rotated it 180 degrees, then moved it 800 feet down I-70 and placed it on its permanent abutments. The bridge was moved using four lines of Self Propelled Modular Transporters (SPMTs). The move was completed, and I-70 was opened to traffic 4.5 hours ahead of schedule.