Interstate 405 through Huntington Beach and Westminster is scheduled to fully close from approximately 11 p.m. to 7 a.m. on Saturday, Aug. 18 and again on Saturday, Aug. 25 as part of the I-405 Improvement Project.

The full freeway closures are necessary to safely demolish the McFadden Avenue bridge. The bridge is the first 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.

During the freeway closures, northbound drivers will be detoured off the freeway at Beach Boulevard, and southbound motorists will be detoured off the freeway at Bolsa Avenue/Goldenwest Street.

Nighttime lane closures on I-405 are also expected during the weeks of Aug. 20 and Aug. 27 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 www.octa.net/405map.

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 www.octa.net/405improvement to sign up for construction alerts via automated call, text message or email.