I-25 Between SH 119 and SH 66 - Longmont, CO

Project Focus
This $48.6 million project for the Colorado Department of Transportation reconstructed 4 miles of I-25 from north of SH 119 to north of SH 66 as part of the planned widening of I-25 from New Mexico to Wyoming. The project scope included removal of the existing pavement with major grading and drainage improvements to accommodate widening from 4 to 6 lanes, 247,000 square yards of 13” thick PCCP, removal and replacement of 5 bridges, traffic signalization and electrical work, 100 acres of seed and mulch, extensive erosion control, asphalt patching, 9 miles of fencing, retaining walls, 11 miles of rumble strip grinding, pavement marking, traffic control and construction of a new 3 acre Park & Ride facility at the SH 66 Interchange.

Project Details
Schedule & Complexity
The original design called for a 12-phase project, with a mandatory completion date of November 20, 2009. Although the project was bid on May 24, 2007, Notice-To-Proceed was not issued until August 28, putting the project at a two month handicap from the beginning. CDOT approved a Contractor submitted Value Engineering proposal which reduced the phases to 2 by moving the detour locations and using an overlaid section of existing frontage road to carry traffic. The resulting 2-phase project eliminated a conflict between the highway paving and the falsework towers under the SH 66 bridge and greatly reduced the required amount of detour pavement. These combined to reduce the number of traffic switches and impact to the traveling public, resulted in a safer construction zone and larger construction work areas, which allowed improvement in the quality of the final product, as well as realizing significant cost savings. The project achieved substantial completion in June, 2009 and was accepted on October 7, 2009. CDOT used URS Corporation as principal design consultant and PBS&J for construction management, with Geocal and Rocksol Consulting Group providing QA testing and inspection. Thirty-three Subcontractors and fifteen major suppliers completed the team.

Construction & Innovation
The Contractor cooperated with CDOT to construct two pilot sections of Roller Compacted Concrete (RCC) for evaluation of this technology as a final wearing surface for special CDOT applications. RCC was used for the west end tie-in to the PCCP reconstruction of SH 66, from the 2 lanes of existing asphalt to the new 5 lane PCCP alignment. RCC was also used on the new CR-28 underpass. The Project Team also revised the north end NB I-25 tie-in from the original asphalt designed section to PCCP. This change provided a permanent section that will not have to be removed for the future I-25 widening, with the increased shoulder widths providing a safer roadway section.

All existing concrete pavement was recycled on site, removed and crushed to produce the aggregate course underlying the new PCCP. In addition, all existing asphalt pavement was milled by the project asphalt subcontractor and hauled to his plant site for future recycling.

Safety
With such a busy worksite, safety was the number one priority. Four lanes of traffic were maintained at all times, utilizing two runs of approximately 8 miles of portable concrete barrier separating NB and SB I-25 from the construction area. A project-specific safety plan was implemented and continuously updated as events dictated. Weekly safety meetings were attended by all on-site members, and Methods of Handling Traffic were updated with combined input. The phasing re-design allowed construction of a temporary detour on a service road, improved the road condition, kept open business access, shortened the schedule, minimized impacts and provided for a safer work zone.

Quality
Working closely with CDOT’s QC/QA consultants, the Contractor executed its long standing Corporate Quality Control plan. In addition to the QC testing for measurement of the success of quality processes, core level training of all craft positions is required on each and every crew. These processes resulted in the project receiving full incentives for pavement and smoothness.