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Nightly Freeway Lane and Ramp Closures Begin for I-405 Improvement Project

Drivers are encouraged to check for updated closure information on

ORANGE – Intermittent nighttime lane and ramp closures on I-405 will begin tonight and continue routinely as construction for the I-405 Improvement Project ramps up.  

Tonight, overnight lane and ramp closures are expected between Seal Beach Boulevard in Seal Beach and Magnolia Street in Fountain Valley. Additional closure information is available and updated in real-time on a mobile-friendly, interactive map available at

Nightly closures will start as early as 9 p.m. and are expected to be finished by 5 a.m. weekdays and 7 a.m. weekends. It is recommended that drivers plan ahead to avoid delays by checking the interactive map and signing up for weekly construction alerts on the project website. All necessary freeway lane closures for the project are expected to occur overnight.

The $1.9 billion highway project, the largest under construction in California, is being led by the Orange County Transportation Authority, in partnership with Caltrans. The project adds one regular lane in each direction, between Euclid Street and I-605, as promised to voters through Measure M, Orange County’s half-cent sales tax for transportation improvements. The project also adds a second lane in each direction, which combined with the existing carpool lanes, will create the 405 Express Lanes.

Weather permitting, construction activities will continue over the next few months, including restriping portions of the freeway and setting up concrete barrier on the outside of the freeway to protect work areas for activities such as tree removals and grading.

More significant construction activities, such as the first paving operations and bridge demolition activities, are anticipated to begin in the fall. The project is set to be completed in 2023.

For more information on the I-405 Improvement Project or to sign up for construction alerts, visit

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