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/485551
PROJECT North Milliken Avenue Railroad Underpass Bridge Value-engineered redesign demonstrates economy of high-performance precast concrete©1 by Jay Holombo and Peter Smith, T.Y. Lin International, and Jon Grafton, Oldcastle Precast Inc. The value-engineering cost proposal (VECP) redesign of the North Milliken Avenue Railroad Underpass Bridge demonstrates that significant savings can be achieved by using highperformance precast concrete instead of structural steel for railroad underpass structures with spans exceeding 80 ft. Further benefits of high-performance precast concrete demonstrated by this VECP redesign include rapid construction, enhanced aesthetics, and low maintenance. Project Background Located less than 1/4 mile south of an interchange with Interstate 10, this busy railroad crossing is at the nexus of a significant freight and a commercial truck corridor. Prior to construction, exiting truck traffic backed up onto the freeway when blocked by a train crossing North Milliken Avenue, causing major delays and a significant safety hazard. The railroad needed to be elevated over the arterial because of the proximity and geometry of an adjacent freeway interchange to the crossing. As a result, the railroad underpass bridge is a highly visible element in the community. Elevating the line at the underpass approaches required the construction of a precast T-wall-based retaining wall system extending approximately one half mile on both sides of the tracks. This was needed to meet right-ofway requirements. The underpass and approaches were constructed in two phases, allowing the busy railroad line to continue in full operation during construction. Initially designed as a steel girder bridge with a steel plate forming the deck, the underpass is a two-span bridge measuring 171 ft long by 52 ft wide. Seven-foot-deep precast concrete fascia beams on each side support maintenance walkways, railings, and communication conduit. They are designed to be sacrificial to protect the main structural beams and can be removed and replaced if there is ever an accidental over-height truck impact. The fascia beams were cast with an architectural formliner to give the exterior surface an ashlarstone appearance bordered with granite bands, which gives the overall structure a pleasing profile that blends well with the adjacent T-wall panels. PROFILE NORTH MILLIKEN AVENUE RAILROAD UNDERPASS BRIDGE / ONTARIO, CALIFORNIA BRIDGE DESIGN ENGINEER: T.Y. Lin International, San Diego, Calif. PRIME CONTRACTOR: C.C. Myers Inc., Rancho Cordova, Calif. PRECASTER: Oldcastle Precast, Perris, Calif.—a PCI-certified producer POST-TENSIONING CONTRACTOR: Dywidag Systems International (DSI), Long Beach, Calif.