Better Roads Digital Magazine
Issue link: http://read.dmtmag.com/i/358505
14 August 2014 Better Roads the third and final stage is started, which is converting traffic over to the second stage and then demolishing the remainder of the existing bridge. This is when the remainder of the new girders are installed and then opening the freeway up to all new traffic. This is all being accomplished while the freeway remains open and only partially reduced to traffic. The freeway is never completely closed to traffic. For more information on this project, go to i-5info.com/i-5-south. Oldcastle Precast Produces Longest Precast-Prestressed Bridge Girders for Caltrans As part of the California Department of Transportation's (Caltrans) $1.6 billion Santa Ana Freeway (I-5) South Corridor Improvement Projects, Perris, Calif.-based Oldcastle manufactured precast-prestressed concrete super girders to construct the Norwalk-San Antonio Bridge undercrossing section of the project. The project's general contractor, Sylmar-California-based Security Pav- ing, contracted Oldcastle Precast- Per- ris to produce a 20, 158-foot-long, precast-prestressed concrete super girders. The super girders are wide flange beam design and were 8,500 psi in compressive strength. The first stage, consisting of seven Oldcastle Precast super girders, were set in place in two nights, for the new Norwalk-San Antonio Bridge under- crossing in Norwalk, California. This 158.5-foot long by 7-foot high bridge girder is the longest and the heaviest – which weighs in at 200,000 pounds – ever produced and set for a Caltrans project, according to the agen- cy. Previously, according to Caltrans, the longest prestressed concrete girders were built on site at the State Route 2 Azusa Canyon Bridge in the San Gabriel Mountains in Los Angeles County. The San Antonio Bridge undercross- ing is being constructed in three stages, according to Oldcastle Precast – Perris. The first stage entailed seven girders; the second stage contained four gird- ers; and the third stage contained nine girders. The bridge is composed of pre- stressed girders, all of which are 158 feet long, supported by cast-in-place abutments that are transverse to the span and then a cast-in-place decking is placed atop the girders. The benefits of this type of bridge construction include: decreased construction time, improved safety for construction per- sonnel and the public, improved struc- tural performance and durability, and cost saving advantages. For more photos, go to i-5info.com/ photos. Better Roads also took some time to talk with Oldcastle Precast about this project in this Q&A: 1. Why was Oldcastle brought onto the job? Oldcastle has cast some of the larg- est/longest girders to date in Cali- fornia for Caltrans. 2. Did the contractor have any spe- cial quality requirements that the precast concrete girders helped to achieve? Yes, This being a Caltrans project, as per the project special provi- sions, all precast girders are re- quired to be manufactured only by a Caltrans pre-approved fabrica- tor. All quality requirements must follow PCI standards and project specific Precast Concrete Quality Control Plan (PCQCP). 3. What was the overall amount of formwork used? Describe how it was used (i.e., forming sequence): More than $250,000 of specially designed steel forms. Helser Indus- tries manufactured the forms for Oldcastle. 4. What are the major challenges on this project? • Ensuring the girder can be fabri- cated, transported and erected at the jobsite. • The girder weight itself is 100 tons so a special lifting device is required. • Fabrication: a) The required pre- stress force is 2,724, 400 pounds, and safety is the top concern. b) The required prestress force is exceeded our cast bed capacity. c) Due to girder narrow web, wider bottom bulb and heavy reinforce- ment in the girder, to ensure no honeycombing at the bottom bulb of girder is critical.) Review plant equipment to ensure they can produce and transport to storage area.