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The iconic Mulholland Bridge that spawned two unprecedented weekend closures of the nation’s busiest freeway and introduced the word “Carmageddon” into the American vernacular was fully reopened to traffic in Los Angeles at 6 a.m. Wednesday after nearly two-and-a-half years of intensive bridge reconstruction work.

The contractor, Kiewit Infrastructure West, implemented the final traffic switch, signal and lane striping work needed to reopen the new northern half of the bridge, returning all lanes to full capacity in time for the mid-week morning rush hour today. Approximately 20,000 vehicles travel over the bridge on a daily basis.

The return of the new bridge to full capacity is the latest milestone for the I-405 Sepulveda Pass Improvements Project, which is building a 10-mile carpool lane on the northbound I-405 between the 10 and 101 freeways.  As the administrator of the design-build project, Metro and its project partner Caltrans have committed to continue opening parts of the massive freeway widening project as soon as they are deemed safe and ready for public use.

At 82 feet wide, 75 feet high and 608 feet long, the new bridge is both wider and longer than the original bridge built in 1959. It also has a similar lane configuration as the original bridge, but now has dual widened sidewalks, a widened center median, and is designed to meet the latest seismic standards.  The bridge also now has four columns rather than the original bridge’s three for increased structural integrity.  Most importantly, the bridge’s new columns are now in the proper location to accommodate the additional northbound 405 freeway lane that is currently under construction.

The contractor will continue to complete minor bridge work as required. As of today, all traffic movements and lane configurations are now operating according to the bridge’s final design.

“Mulholland Bridge, arguably the most famous freeway bridge in recent memory, has required a Herculean effort to rebuild while more than 300,000 motorists drive underneath it every single day,” said Diane Dubois, the Chair of the Metro Board of Directors. “This bridge and the entire project has been a massive undertaking. Metro and its project partners are continuing to deliver the goods.  We are making critical infrastructure investments that will benefit everyone who chooses to drive the freeways in L.A. County.”

Approximately 183,000 labor-hours have been expended on rebuilding the bridge.  Reconstruction has taken place over 29 months since the first southern half of the bridge was demolished in July 2011.

“This is a great day for L.A. commuters and certainly one for the history books,” said Zev Yaroslavsky, County Supervisor and Metro Board Member. “The Mulholland Bridge, whose phased demolition threatened two ‘Carmageddon’ traffic jams on one of the world’s busiest freeways, is now rebuilt. It’s seismically updated and now serving the motoring public. We’re on the home stretch of the long and complex 405 project. We’ll finish it next year, and restore a semblance of normality to the Sepulveda corridor.”

Bridge demolition officially began the weekend of July 16-17, 2011, when contractor work crews removed the southern half of the bridge.  It was April 2011 when an incredulous public first learned about a freeway closure so gigantic that it captured international headlines.  The 405 had never been deliberately closed for 10 miles in a dense urban environment like Los Angeles.

“Caltrans congratulates our partners on the opening of another part of the I-405 widening project, the iconic Mulholland Bridge” said Carrie Bowen, acting Caltrans District 7 director. “We look forward to the overall improvements through the Sepulveda Pass along I-405.”

 Metro launched an aggressive, multi-agency public outreach campaign advising motorists to “Plan Ahead, Avoid the Area or Stay Home” in efforts to achieve up to two-thirds traffic diversion and suppression of freeway traffic during the bridge’s demolition.  Caltrans posted alerts on its changeable message signs throughout the State of California. Law enforcement and emergency response teams were readied for a host of contingencies if the public did not heed the call to stay away from the closure area.

The contractor executed a precision traffic management and demolition operation, and completed demolition 17 hours ahead of schedule. There were no threats to public safety the entire weekend, and traffic conditions were the lightest seen in decades.

The second demolition for the northern half of the Mulholland Bridge took place the weekend of September 29-30, 2012.  Public agencies employed a similar public outreach campaign to deter motorists from using the L.A. freeway system to avoid congestion.  With more work to perform, the contractor still successfully completed demolition work five hours ahead of schedule.

Public cooperation ensured the success of both freeway mega-closures. For Carmageddon I, the project team achieved up to 65 percent traffic diversion and suppression. For Carmageddon II, the project team achieved up to 50 percent traffic diversion and suppression.  The closures spawned numerous local community events, and led many to call for more car-free weekends in Los Angeles, the car capital of the world.  The successful operations and multi-agency public outreach campaign are now considered a case study for how to conduct a major freeway closure in the United States.