Featured graphic for the Orange County Transportation Authority

I-405 near Magnolia Street set to close overnight April 4 and 11

I-405 between Magnolia Street and Warner Avenue is scheduled to fully close overnight on April 4 and again on April 11 to allow crews to safely demolish the second half of the Magnolia Street bridge as part of the I-405 Improvement Project.

Drivers should expect delays in the area and are encouraged to use alternate routes if possible. The closures, scheduled for 10 p.m. Saturday, April 4, to 9 a.m. Sunday, April 5, and 10 p.m. Saturday, April 11, to 9 a.m. Sunday, April 12, include:

  • Both directions of I-405 between Magnolia Street and Warner Avenue
  • Northbound I-405 on-ramp from westbound Warner Avenue
  • Northbound I-405 loop on-ramp from northbound Magnolia Street
  • Southbound I-405 loop on-ramp from southbound Magnolia Street

In addition, the northbound I-405 loop off-ramp to Westminster Boulevard is scheduled to close for approximately one year beginning April 6 to allow crews to reconstruct the ramp as part of the freeway widening.

Detours will be in place to guide drivers around the closures. Up-to-date closure and detour information is available on the project’s interactive map at octa.net/405map or on the project mobile app. To download the free app, search for 405 Improvement in the App Store or Google Play.

The Magnolia Street bridge, which straddles the cities of Fountain Valley, Huntington Beach and Westminster, is being demolished and reconstructed in two stages, one half at a time, allowing it to remain open to traffic in both directions during construction. The first reconstructed half of the new Magnolia Street bridge opened to traffic on March 30, and reconstruction of the second half of the bridge is expected to take approximately one year to complete.

It is one of 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 Magnolia Street bridge is being reconstructed to accommodate the widening of I-405. Improvements to the bridge also include increasing the total number of lanes from four to six and adding sidewalks and bike lanes in each direction.

The $1.9 billion I-405 Improvement Project will add one regular lane in each direction between Euclid Street and I-605, and a second lane in each direction in the center of the freeway from SR-73 to I-605 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 drivers routinely face severe congestion in both the regular lanes and carpool lanes. The project is critical to accommodate expected employment, population and housing growth throughout the region.

The speed limit on I-405 has been reduced to 55 mph between SR-73 and I-605 for the safety of drivers and construction crews for the duration of the project, which is expected to be completed in 2023. Drivers are advised to slow down and proceed with caution whenever signs of highway work are present, and drivers whose vehicles become disabled should pull off at the nearest exit, if possible.

For more information about the I-405 Improvement Project, visit octa.net/405improvement.

This article was released by the Orange County Transportation Authority.