Orange County Branch Newsletter

March 2020

ASCE OC Branch & YMF

I-405 Widening Construction Technical Tour

By Jason Fix, PE | Programs Committee Co-Chair

ASCE OC Branch & YMF coordinated with Azzam Saad, Contracts Manager for OC405 Partners and Billy Parent, Public Relations Specialist for OC405 Partners, to tour Interstate (I) 405 freeway construction site. The freeway widening will ultimately extend from I-605 juncture to State Route (SR) 73 in the south. It will encompass 18 bridge replacements, interchange reconfigurations, and merge lane improvements in order to add two new lanes in each direction.

The first stop on the tour was the Talbert Ave Overcrossing. This structure will ultimately be an approximately 435-foot-long structure. The bridge will be a Cast-In-Place Prestressed Box Girder Bridge. The abutments and columns are currently constructed; the soffit slab will be cast next on falsework, which will span the open I-405 freeway. The final top slab will be cast last. The over 50 degrees skew of Talbert Ave created longer spans over the freeway due to being at an angle.

McFadden Ave Overcrossing had similar geometry due to the freeway location. To align with the edge of the freeway the abutments, retaining foundations supporting the roadway superstructure, have lengths over 150 feet. Multiple rows of piles were required to provide sufficient foundation capacity. In 24-inch-diameter Cast-in-Drilled-Hole piles, tubes are placed for gamma-ray testing. This is used to find voids in the pile concrete which could compromise its capacity.

The tour ended at the batch plant which was set up for the I-405 project. A temporary plant has been constructed in the space adjacent to the Beach Boulevard off-ramp. At this location, the aggregate and cement are mixed to create the concrete required. With its close location, the necessary volume of material can be processed efficiently without much time lost to transportation.

About the Author

Jason Fix, PE, is a Bridge Engineer for McLean & Schultz. He has over 10 years of experience working on bridges and structures in Orange County. He is interested in exploring the civil engineering field and sharing knowledge within the professional network. Jason can be contacted at [email protected].


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