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United States

I-405 Highway Express Lane Upgrade and Improvements

Design Solutions on an Expedited Schedule


When the Orange County Transportation Authority (OCTA) undertook a complex $1.9 billion design-build project to improve and expand sections of the I-405 Highway, many technical and scheduling challenges had to be overcome to ensure success.

The project included the construction of one general purpose lane in each direction of I-405 from Euclid Street to the I-605 interchange and an additional median lane in each direction from SR-73 to the I-405/SR-22/East interchange to be managed jointly with the existing HOV lanes as a tolled express facility from SR-73 to I-605. The improvements required the construction of eight new structures, replacement of 18 overcrossing structures, and six structure widenings/modifications.

Right-of-way access across the 17-mile project corridor was very limited both on local streets and along the highway. The freeway envelope is often only a few feet, leaving limited space for construction staging. Additionally, the delivery schedule was very compressed, requiring the quick turnaround of a high-quality design package.


The project was divided into seven segments delivered simultaneously. TRC led the design of Segment 1.3, a highway widening from Talbert Avenue to Slater Avenue in the City of Fountain Valley that required the rebuilding of three overcrossings. Our team also implemented improvements along three local streets within the segment limits including upgrading curb ramps, sidewalks, and driveways to be ADA-compliant. We also prepared the pavement delineation and sign plans for the entire 17-mile corridor, coordinating across all seven project segments. Additionally, our team provided overall Maintenance of Traffic coordination between the seven design segments.


TRC delivered the design package on an expedited schedule with close coordination between the construction contractor, Caltrans District 12, OCTA, the city, and leaders of the other design segments to ensure consistency between design plans. Our careful communication throughout the project helped minimize revisions needed in the design phase. Segment 1.3 was one of the first three segments to be approved and the rebuilt Slater Avenue Bridge was the first new overcrossing to open within the entire project.

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