405 Freeway Improvements

What to expect during the five-year construction project

More than 300,000 vehicles traverse Interstate 405 in Orange County per day, and traffic along the corridor is expected to grow approximately 30 percent by 2040. To accommodate and prepare for the increased demand, the I-405 Improvement Project will upgrade 16 miles of I-405 between State Route 73 in Costa Mesa and I-605 near the L.A. County line. Scheduled to start in early 2018, the five-year project will add four new travel lanes, introduce express lanes, and make improvements to entrances, exits, and bridges. Here’s what to expect during construction:

What should drivers expect?

Trees and vegetation will be temporarily cleared to allow space for construction. Concrete barriers will be set up outside the far right lane of the freeway. Since this is an expedited “design-build” project, work may be simultaneously performed in multiple areas.

What do you need to know now?

In 2018, construction will begin on bridges for Bolsa Chica Road, Westminster Avenue, Goldenwest Street, Magnolia Street, Slater Avenue, the Santa Ana River, Harbor Boulevard, and McFadden Avenue. All these bridges will remain open to traffic during construction except for McFadden.

What hours will construction take place?

Most activity will take place during the day; however, some work will be done at night and on weekends. The majority of lane closures needed for bridge demolition and other construction will occur between 10 p.m. and 5 a.m. 

How much time should drivers add to their commute so they arrive at their destination on time?

Starting in early 2018, there may be up to an additional 30-minute delay. 

If you have questions, call the 405 Community Outreach Team at 1-888-400-8994 or email 405project@octa.net. For more information, visit octa.net/405improvement.