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Reconstructed half of Magnolia Street bridge over I-405 set to open March 30

Crews are scheduled to shift traffic to the first reconstructed half of the new Magnolia Street bridge on Monday, March 30, as part of the I-405 Improvement Project.

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.

It is one of 18 bridges to be built, widened or replaced as part of the I-405 Improvement 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 new portion of the Magnolia Street bridge will be the first to open among the project’s two-stage bridges. The Slater Avenue bridge, which was fully demolished and reconstructed in one go, was the first reconstructed bridge to open to traffic in August.

The traffic shift will require a 55-hour closure of the southbound freeway ramps at Magnolia Street from 10 p.m. Friday, March 27 to 5 a.m. Monday, March 30. In addition, Magnolia Street between Recreation Circle and Heil Avenue is scheduled to close:

  • 10 p.m. Thursday, March 26, to 5 a.m. Friday, March 27
  • 10 p.m. Friday, March 27, to 6 a.m. Saturday, March 28
  • 10 p.m. Saturday, March 28, to 6 a.m. Sunday, March 29
  • 9 p.m. Sunday, March 29, to 5 a.m. Monday, March 30

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.

Work on this portion of the Magnolia Street bridge began in December 2018, and the second portion of the bridge is expected to be demolished next month. Reconstruction of that section is expected to take approximately one year to complete.

Construction updates, including the latest closure and detour information, are available on the project’s interactive map at octa.net/405map or on the project’s mobile app. To download the free app, search for 405 Improvement in the App or Google Play stores.

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.