Project Description:

QPEC was involved with the conceptual, preliminary, final design and construction services of the interchange over I-25 in Las Vegas, New Mexico. This new bridge had to be designed and built on the existing alignment using ABC (Accelerated Bridge Construction) methods to reduce long traffic detours and save motorists thousands of miles and many hours of driving time around the construction project. First, the substructure elements were constructed under the existing bridge while it remained in service. Afterwards, the removal of the existing bridge and the installation of the new superstructure would only take 45 days. Due to the requirement of maintaining the final grade, as well as the same reduced vertical clearance, the most suitable precast element for the superstructure were prestressed concrete box girders. These girders would allow one intermediate bridge support and accommodate the new abutments close to the existing bridge abutments. During the excavation of the new abutment foundation, it was required to protect the existing abutments with retaining earth elements. For this purpose, a top down soil nailing excavation method was performed. Per recommendation of the geotechnical engineer, the foundation had to be on piles. Drilled shaft foundations are typically used throughout the state, but the equipment used for drilled shaft construction could not fit under the bridge. For this reason, micro piles were selected. The bridge foundation, the abutment stems and the pier columns consist of cast in place concrete. The rest of the substructure components are precast elements.