Sat. Mar 2nd, 2024


I-405 set to Close Overnight Saturday in Fountain Valley

I-405 is slated to shut down in both directions from 11 p.m. to 8 a.m. on Sept. 29 and Oct. 6 between Brookhurst and Magnolia streets

ORANGE – Interstate 405 through Fountain Valley is scheduled to fully close from approximately 11 p.m. to 8 a.m. on Saturday, Sept. 29, and again on Saturday, Oct. 6, as part of the I-405 Improvement Project.

The full freeway closures are necessary to safely demolish the Slater Avenue bridge. The bridge is the second of more than 18 bridges to be built, widened or replaced as part of the project, which will speed up travel times on I-405 between Costa Mesa and the Los Angeles County line, an area traveled by more than 370,000 vehicles a day. The McFadden Avenue bridge was demolished last month.

During the freeway closures, northbound drivers will be detoured off the freeway at Brookhurst Street, and southbound motorists will be detoured off the freeway at Magnolia Street.

Nighttime lane closures on I-405 are also expected during the weeks of Oct. 15 and Oct. 22 for additional demolition activities, but those will not require the freeway to be fully closed.

Drivers should expect nighttime delays in the area and are encouraged to use alternate routes if possible. Up-to-date closure and construction information is available on the project’s interactive map at

The $1.9 billion I-405 Improvement Project will add one regular lane in each direction between SR-73 and I-605 and a second lane in each direction in the center of the freeway that will combine with the existing carpool lanes to form the 405 Express Lanes.

This 16-mile segment of I-405 is one of the most heavily traveled stretches of highway in the nation, and both the regular lanes and carpool lanes are heavily congested during rush hour and on weekends. The project is critical to accommodate expected employment, population and housing growth throughout the region.

It currently takes drivers about an hour to travel this section of freeway during rush hour and without the project, the commute is projected to double in the next 20 years. Once the project is finished in 2023, it is expected to take about 30 minutes to drive the 16 miles during rush hour in the regular lanes and about 15 minutes in the 405 Express Lanes.

People are encouraged to visit the project website at to sign up for construction alerts via automated call, text message or email.

By Editor

The New Santa Ana blog has been covering news, events and politics in Santa Ana since 2009.

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