Inside Seven
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The south side of the Mulhollard Bridge, looking west.

I-405 Summer Weekend Closure Planned
by  Judy Gish
Issue Date: 06/2011

Motorists are Advised to Avoid Delays by Staying Home

In what might be considered one of the most significant freeway events in Los Angeles history, the San Diego Freeway (I-405) will close in both directions for 53 hours beginning Midnight Saturday, July 16 until 5 a.m. Monday, July 18.

Northbound I-405 will be closed from the Santa Monica Freeway (I-10) to the Ventura Freeway (U.S. 101). Southbound I-405 will be closed from U.S. 101 to Getty Center Drive.

The closure is necessary to replace the Mulholland Bridge as part of the northbound I-405 HOV lane construction project between the Santa Monica Freeway (I-10) and the Ventura Freeway (U.S. 101). When completed, this project will create a continuous HOV lane in both directions of I-405 in Los Angeles County.

Motorists will be directed to use alternate freeways if they absolutely must travel over that weekend, however back-ups are expected to be severe on both freeways and streets. Those who must travel are advised to plan their routes in advance using prescribed detours, monitor real-time traffic and to be aware that they could be delayed by several hours.

“The best way to minimize closure impacts is to restrict driving to essential trips only and stay as close to home as possible,” said Caltrans District 7 Director Mike Miles.

“This closure is unavoidable,” he added. Unlike replacement of the I-405 Skirball Drive and Sunset Boulevard bridges, neither of which required significant closures, the Mulholland Bridge spans the width of the freeway without center support. For this reason, even though only the east side of the bridge is being demolished in this operation, the freeway must be closed in both directions to protect public safety.

Changeable Message Signs posted at key interchanges throughout the county as well as selected permanent signs throughout the state will inform motorists of the closure in advance, allowing them to change their route or avoid the area. Travelers also can adjust their plans to include rail service, which will be increased during the closure.

Emergency vehicle access will be provided on the closed segments of I-405 for first responders to access the freeway, construction area, and neighborhoods within the Sepulveda Pass. Additionally, emergency first responders such as police and fire personnel will be stationed in multiple locations throughout the closure area to minimize response times.

Caltrans and the CHP will monitor the closure constantly from the district Traffic Management Center (TMC) and respond immediately to any traffic incidents. Caltrans Public Information Officers, as well as those from Metro, the Los Angeles Department of Transportation, police and fire departments will maintain a 24-hour presence at a public/media information command center (location TBD).

Weekend demolition dates were selected to minimize impacts to rush-hour commuters, local communities and event centers as much as possible. Work is also planned to coincide with the summer recess of local schools and universities and usual vacation periods.

The bridge demolition and reconstruction work will be conducted in two phases, eastern first and then western. That’s good news because it will minimize the time and therefore the impacts of this coming closure. It will also, however, mean that there will be another closure sometime next year when the second part of the work is performed.

The bridge's deck will be removed first, then the support structure and columns. The freeway underneath the structure will be protected by a thick layer of dirt that will prevent falling debris from damaging the roadbed. Two pillars will remain standing to provide support to the west side of the bridge. The dismantled structure will be recycled.

In addition to the HOV lane, project benefits include improved freeway safety through standardized lane and shoulder widths, greater ramp capacities at key locations, new sound and retaining walls, widened overpasses, widened and seismically updated bridges and new landscaping within the project corridor.

The $1 billion design/build project is a joint effort between Caltrans and the Los Angeles Metropolitan Transportation Authority (Metro) and is being constructed by Kiewit Infrastructure West Co. It is scheduled for completion in 2013. To obtain up-to-the-minute closure information, visit the project web site at or follow the project on twitter: and Facebook at

Future widening of Sepulveda Boulevard north of the Montana Avenue overcrossing. These girders have been placed for the expanded Montana Avenue undercrossing. The photographer was facing east with the freeway  behind. (Photo courtesy of the Metropolitan Transportation Authority (c) 2011.)
Crews are standing on I-405 south and watching the raising of a bridge girder for the widened Sunset Boulevard Bridge.
(Photo courtesy of the Metropolitan Transportation Authority (c) 2011.)