ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.
Issue link: http://www.aspiremagazinebyengineers.com/i/768999
PROJECT Las Vegas Airport Interchange New Mexico builds a bridge under a bridge to accelerate schedule by Raymond M. Trujillo, New Mexico Department of Transportation In New Mexico, many bridges carrying interstate traffic or local roads over interstates are reaching the end of their design and service lives. Due to increased traffic volumes and vehicle weights, many of these are considered functionally or structurally deficient. The state is methodically prioritizing and replacing these structures yearly. In 2012, the bridge carrying frontage road (FR) 2142 over Interstate 25 (I-25) in Las Vegas, N.Mex., was determined to be structurally deficient and rapidly deteriorating. Replacement of this bridge, the Las Vegas Airport Interchange, became a priority for the District 4 office of the New Mexico Department of Transportation (NMDOT). Background The NMDOT engineers established the need to reduce the duration of construction and minimize inconvenience to the travelling public because closure of the bridge would require a 5-mile detour to access the airport. The existing alignment and profile grade were to be maintained to eliminate the cost and time required for reconstruction of the approach roadway. The bridge design engineer proposed replacing the existing five-span bridge with a two-span structure, placing the center pier between the two existing median shoulder piers. Early on, the NMDOT Bridge Design Bureau recommended incorporating accelerated bridge construction (ABC) techniques. For this bridge, a reduced closure could be accomplished by constructing the foundation and part of the substructure under the existing bridge while it remained in service. In addition, prefabricated bridge elements and systems (PBES) components would be used. NMDOT has had success with this method on previous bridge projects. The new Las Vegas Airport Interchange Bridge is 170 ft long and 36.17 ft wide. It carries two, 12-ft-wide travel lanes and two, 4-ft 7-in.-wide shoulders plus 1-ft 6-in.-wide barrier rails. Methods Used to Accelerate and Accommodate Under- Bridge Construction • Construction of abutments and piers under existing bridge • Abutment excavations stabilized with retaining walls and soil nails • Drilled, cast-in-place concrete micropiles • Precast concrete abutment caps with back walls • Precast concrete pier cap • Precast concrete wingwalls • Shallow adjacent precast concrete box girders • Transverse post-tensioning • Reduced thickness cast-in-place concrete composite deck that required no supporting formwork PROFILE LAS VEGAS AIRPORT INTERCHANGE / LAS VEGAS, NEW MEXICO BRIDGE DESIGN AND CONSTRUCTION ENGINEER: Quiroga Pfeiffer Engineering Corporation (QPEC), Albuquerque, N.Mex. PRIME CONTRACTOR: El Terrero Construction LLC, Rio Rancho, N.Mex. PRECASTER: Coreslab Structures (ALBUQUERQUE) Inc., Albuquerque, N.Mex.–a PCI-certified producer POST-TENSIONING CONTRACTOR: El Terrero Construction LLC, Rio Rancho, N.Mex.