New phase of demolition of Magnolia Street bridge causes overnight closures on 405 Freeway

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The old half of the Magnolia Street bridge over the 405 Freeway in Fountain Valley is being demolished so it can be reconstructed. The work will cause freeway closures between Magnolia Street and Warner Avenue.
(Courtesy of Orange County Transportation Authority)

Part of the 405 Freeway is scheduled to fully close overnight Saturday and again April 11 while crews demolish the old half of the Magnolia Street bridge in Fountain Valley so it can be reconstructed.

The other half was reopened to traffic Monday after being demolished and rebuilt in a project that began at the end of 2018.

The new demolition will cause shutdown of the northbound and southbound sides of the 405 between Magnolia Street and Warner Avenue from 10 p.m. Saturday to 9 a.m. Sunday and for the same period next weekend, according to the Orange County Transportation Authority. Detours will be in effect.

Additional demolition work will cause freeway lane closures between 10 p.m. and 5 a.m. weeknights beginning Monday and continuing for several weeks, OCTA said.

    The Magnolia Street bridge is being rebuilt to increase the number of traffic lanes from four to six and have bike lanes and sidewalks in both directions. The new phase of the reconstruction is expected to take about a year.

    The bridge is one of 18 that will be replaced, enlarged or built as part of a $1.9-billion project to widen the 405 between the 73 Freeway in Costa Mesa and the 605 Freeway near Rossmoor.

    Once that project is completed in 2023, both directions of the freeway on the 16-mile stretch will have an additional general-purpose lane and a new “express” toll lane, according to OCTA. The existing carpool lane in each direction will be converted to an express lane.

    For more information about the project, visit

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