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Completed Projects

405 completed

Whether you are heading to Orange County's beautiful beaches, shopping at world-class retail centers, experiencing live performances, catching flights, commuting to work or carpooling children, chances are you will use the San Diego Freeway (I-405)/Costa Mesa Freeway (SR-55) interchange. More than 433,000 motorists traverse this interchange daily, making it one of the 10 busiest in the United States.

The $135.8 million project designed to improve traffic flow and safety at the I-405/SR-55 interchange near Costa Mesa was completed at the end of September 2005. Access to shopping, business and entertainment clustered in the South Coast Metro area of Costa Mesa was improved. The new "braided" configuration eliminated traffic weaving and improved traffic safety for vehicles exiting at Bristol Street from northbound I-405 in relation to motorists traveling southbound on SR-55 connecting to northbound I-405. The final improvement for this area, the addition of an on-ramp to northbound I-405 from Anton Boulevard, was completed and opened on July 5, 2005.

In addition, the following milestones were accomplished:

  • The northbound I-405 to northbound SR-55 direction of the carpool bridge (MOS-1 Project) opened to traffic on December 30, 2004. The southbound SR-55 to Southbound I-405 direction of the bridge opened to traffic on January 28, 2005.
  • The carpool connector bridge between southbound SR-55 and northbound I-405 and the reverse movement (MOS-3 Project) is complete and was opened to traffic on May 5, 2005.


Improvements provided by the I-405/Corona Del Mar Freeway (SR-73) interchange project eliminated chokepoints and the redesigned on and off ramps improved access to the freeway. The SR-73 portion of this project was completed in late 2003. The I-405 portion was completed in July 2004. The entire project was declared complete in July 2004 with the exception of punchlist and change order work.

Christina Byrne

Project Contact

Christina Byrne
Manager of Community Outreach
(714) 560-5717

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