SR-55 (I-405 to I-5)

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  • SR-55 (I-405 to I-5)

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    Associate Community Relations Specialist

    (714) 560-5766
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    There are currently no detours
    Stay Informed

Overview Tab Content:


    The Costa Mesa Freeway (SR-55) is one of the most heavily congested freeways in Southern California. The SR-55 is a vital link to other major freeway systems in Orange County, and it is the only freeway providing a direct north-south connection between Central Orange County and the coastal region. Currently, the SR-55 has four general purpose lanes, one carpool lane and some auxiliary lanes in each direction. There is heavy traffic congestion on SR-55, and future demand is expected to increase congestion. This project is proposing to add new lanes and improve mobility for commuters within Orange County.


    OCTA, in cooperation with Caltrans, is proposing to widen State Route 55 (SR-55) in both directions from just north of the Interstate 405 (I-405)/SR-55 Interchange to just south of the Interstate 5 (I-5)/SR-55 Interchange in the cities of Santa Ana, Tustin and Irvine. The project is currently in the environmental phase.

    The Draft Environmental Document, also called the Draft Initial Study with Proposed Mitigated Negative Declaration/Environmental Assessment (Draft IS/EA), and other project documents were made available to the public on Nov. 25, 2015.

    As a result of comments received during the public circulation of the Draft IS/EA, an additional alternative was included for study – Alternative 3 Modified – which includes:

    • New carpool and general-purpose lanes and additional auxiliary lanes 

    A Supplemental Draft IS/EA has been prepared, which focuses on the analysis of Alternative 3 Modified. The Supplemental Draft IS/EA was released on April 3, 2017, and is available for public review and comment until 5 p.m. May 3, 2017.

    The Supplemental Draft IS/EA and other project documents are available online at, and at the following locations during normal business hours:

    • Caltrans District 12 Office, 1750 East 4th St., Suite 100, Santa Ana, CA 92705
    • Orange County Transportation Authority, 550 South Main St., Orange, CA 92868
    • Santa Ana Public Library, 26 Civic Center Plaza, Santa Ana, CA 92701
    • City of Irvine City Hall, 1 Civic Center Plaza, Irvine, CA 92606-5207
    • Katie Wheeler Library, 13109 Old Myford Road, Irvine, CA 92602

    The documents will not be available at the Tustin Library, as stated in the public notice, due to unforeseen circumstances that require the library to be closed for an unknown duration.

    Do you have any comments about processing the project with a Supplemental IS/EA? Do you disagree with the findings of our study as set forth in the Proposed Mitigated Negative Declaration? Would you care to make any other comments on the project?

    Please submit your comments in writing no later than 5 p.m., May 3, 2017, to:
    Charles Baker, Senior Environmental Planner
    California Department of Transportation, District 12, Environmental Analysis – Specialist Branch
    1750 East 4th Street, Suite 100
    Santa Ana, CA 92705

    Email comments to, or submit your comments at the public meeting, in an open house format, which will be held 6-8 p.m. Thursday, April 20, 2017, at the Delhi Center, 505 E Central Ave., Santa Ana, CA 92707.

    The Draft IS/EA and other project documents released in November 2015 also are available online at

    Si prefiere recibir información en español, por favor llame a Paola Bassignana al 626-744-9872.

Details Tab Content:

    The SR-55 between I-405 and I-5 has four general-purpose lanes and one continuous-access carpool lane in each direction. OCTA and Caltrans are conducting an environmental study for a project to add new lanes to the 4-mile stretch of SR-55 in northbound and southbound directions, between I-405 and I-5. These alternatives are being studied:

    • No-Build
    • Alternative 1 – Add an auxiliary lane between each interchange
    • Alternative 2 – Add one general purpose lane in each direction and remove existing lanes
    • Alternative 3 – Add one general purpose lane and auxiliary lanes in each direction
    • Alternative 3 Modified – Add one general purpose lane, one carpool lane and auxiliary lanes in each direction
    • Alternative 4 – Add one carpool lane and auxiliary lanes in each direction


    The SR-55 Project Outreach Team is available to make a presentation to your neighborhood, organization or business. Please contact us with requests, questions or comments at or 800-724-0353. Or, sign up for our project email alerts by selecting the Stay Informed tab at the top of this page.

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SR-55 Improvements
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