Here's how Los Angeles survived and thrived during two weekend closures of its busiest freeway.

To build a high-occupancy vehicle (HOV) lane, the California Department of Transportation (Caltrans) and the Los Angeles County Metropolitan Transportation Authority (Metro) needed to demolish a bridge. Not just any bridge, but the iconic Mulholland Bridge. And not just any HOV lane, but the last segment of the HOV system on I–405 from west Los Angeles to the San Fernando Valley, which will enable carpoolers to travel in both directions from northern Los Angeles County all the way to Orange County.

Demolish a bridge? That’s no big deal for Caltrans. The trouble was that demolition would require closing a section of one of the busiest freeways in the United States.

As far as local officials and the media were concerned, the planned 53-hour closure would unleash a snarling traffic monster that would bring the city to its knees. That is, unless the vast majority of the 500,000 vehicles that normally travel on I–405 through the Sepulveda Pass on a mid-July weekend in 2011 could somehow stay parked at home. In Los Angeles, where the freeways never sleep? Who were they trying to kid?

Reaching Out to the Public

The key to avoiding chaos was a public outreach campaign to ensure that every man, woman, and child in Los Angeles County, the State of California, and practically the entire western United States would know about the closure. Putting the campaign together involved an enormous effort led by Metro, Caltrans’ partner in this project.

Because it was unthinkable that Californians would forgo their normal trips to and fro, the plan was to warn motorists to expect massive delays -- easily 3 hours or more. Plan ahead; leave early; and, above all, avoid I–405 anywhere near the 10-mile (16-kilometer) northbound closure and the 4-mile (6.4-kilometer) southbound closure.

This was the word conveyed to the public on Caltrans’ changeable message signs all the way from the State’s Oregon border down to Mexico. Specifically, the message signs in southern California read, "405 WILL CLOSE RTE 10 TO 101 JULY 16–17 EXPECT BIG DELAY.” Those posted elsewhere read, "LOS ANGELES FWYS EXPECT BIG DELAY JULY 16–17.” A month ahead of the closure, a total of 64 signs began displaying the message on Los Angeles County freeways. As the date approached, more than 30 additional signs were placed at freeway locations and an additional 40 to 50 on surface streets.

The fact that long after the project’s completion people are still discussing "Carmageddon,” as the closure came to be known, demonstrates the success of the public awareness campaign. But first, a closer look at the project itself and its background.

An Introduction to I–405

When State and local officials gathered on December 21, 1962, to dedicate the newest addition to I–405, an eight-lane, 5.7-mile (9.2-kilometer) section between west Los Angeles and the San Fernando Valley, they were thrilled to provide a quick alternative to the steep turns of four-lane Sepulveda Boulevard, an adjacent road winding over the Santa Monica Mountains.

"With the possible exception of the dedication of the downtown Los Angeles freeway loop last March, this is the most gratifying experience of this kind that I have had,” said then Governor Edmund G. Brown, Sr., in a message read at the ceremony.

Fifty years ago, government officials had envisioned as many as 100,000 vehicles traveling over the route once the 40-mile (64-kilometer) stretch of I–405 was complete from San Fernando to Long Beach. What the agency did not anticipate was that five decades later the Sepulveda Pass section of I–405 would carry traffic levels five times that number.

I–405 is the only freeway directly connecting the coastal cities of Los Angeles with the San Fernando Valley, hence its popularity. Lacking available space for building additional freeways, Caltrans’ strategy for reducing congestion is to maximize the efficiency of the existing freeway, in part by building HOV lanes. For the past decade, the agency has been adding carpool lanes along the route. All that remained to complete the system was the 10-mile (16-kilometer) stretch northbound from the Santa Monica Freeway to the Ventura Freeway.

Remedying Current Traffic Woes

According to Caltrans’ 2011 HOV Annual Report, which contains the latest figures available, Los Angeles County has 514 lane-miles (827 kilometers) of HOV facilities, or 36 percent of the nearly 1,425 lane-miles (2,293 kilometers) of HOV infrastructure in California. On average, each HOV facility in Los Angeles County carries 1,400 vehicles, or 3,400 persons, per hour during peak periods. In all, the HOV facilities in the county carry approximately 326,000 vehicles, or 763,000 persons, daily.

On average, HOV lanes carry twice as many persons as regular-use lanes. That translates to accommodating 33 percent of freeway users in just 20 percent of the space, while an adjacent single mixed-flow lane carries 17 percent of the entire freeway’s users in the same 20 percent of space.

After years of planning, work on the final segment of the HOV lane started in summer 2009. Caltrans and Metro awarded a design-build contract for the carpool lane -- the first such contract let for a freeway project in this part of California. The main advantage to the design-build method is speed of construction, along with greater flexibility to respond to conditions as they arise.

Considering that I–405 through the Sepulveda Pass needed immediate congestion relief, Caltrans officials deemed the project an ideal candidate for design-build. State legislation (SB 1026) passed in 2006 required that the regional transportation agency be in charge of design-build projects. As a result, Metro is responsible for administering the I–405 contract, and Caltrans has oversight. The State picked up 60 percent of the $1.3 billion price tag, while the Federal Government covered 30 percent, including $189 million in funds available through the American Recovery and Reinvestment Act. Local funds paid for the rest.

In addition to constructing the 10-mile (16-kilometer) HOV lane, the project is improving the supporting infrastructure, including ramps, bridges, and sound walls. The project also removes and replaces 3 bridges, realigns 27 on- and off-ramps, widens 13 existing underpasses and structures, and constructs approximately 18 miles (29 kilometers) of retaining wall.

Describing widening and improving one of the Nation’s most congested highways, while keeping it functional, Project Manager Mike Barbour of Metro said in a live Web chat, "This project is as challenging as performing heart surgery on a patient while she runs a marathon.”

The three bridges that needed to be replaced were the Sunset, Skirball, and Mulholland. The project contractor could demolish and reconstruct both the Sunset and Skirball bridges with minimal disruptions to traffic by closing freeway lanes for a few overnight hours over the course of 6 and 7 nights, respectively.

The Mulholland Bridge was another story. Because this bridge had no center bent (a rigid frame commonly made from reinforced concrete or steel that supports a vertical load) and a 60- to 70-foot (18- to 21-meter) vertical clearance, it required significantly more time to demolish. To reduce the impact on local traffic flow, bridge demolition and construction would take place in two phases: the south side first, followed by roughly a year of reconstruction, and then the north side. After the south side was demolished, the north side would be used to carry two-way traffic while the new south side bridge was constructed. Then, the north side would be demolished and the new bridge installed, as traffic flowed in two ways on the south side bridge. Transportation officials and the contractor decided that one painful 53-hour closure was the most efficient way to handle the demolition phases.

Planning for the Closure

Although project officials had been planning for the closure for some time, the exact date -- the weekend of July 16–17, 2011 -- was finalized just 10 weeks before the closure was to occur. In addition to the construction schedule, planners took into account other factors in picking that date, including the fact that schools would not be in session and that, in general, freeway traffic is slightly reduced during the summer months.

With Metro responsible for developing and implementing the outreach plan and Caltrans in charge of alerting motorists throughout the State, information officers from both agencies began hyperventilating as the closure date approached. The plan included several elements: a dedicated Web site and hotline; social media consisting of Twitter, Facebook, a blog, and Web chats; a speakers’ bureau; and weekly email blasts to 6,000 contacts.

As outreach efforts continued, other city and county agencies became involved, including the Los Angeles International Airport, which made sure that its customers from around the globe were aware of the closure.

On the media outreach side, the first of four press events occurred on June 6, 2011, along with distribution of a press release to local, regional, and national media. The first press conference was when reporters embraced the term "Carmageddon,” which Los Angeles County Supervisor Zev Yaroslavsky mentioned in his remarks.

Although paid advertising was part of the outreach plan, it was hardly needed from that point forward. Reporters seized upon the word, the closure, the project -- the entire catastrophe-in-the-making idea -- and began to cover the impending doomsday 24/7.

Before it would be over, hundreds of articles would be written in publications as far away as Europe and stories broadcast on television and radio stations from Los Angeles to New York.

Municipal authorities decided to treat the closure as an emergency response effort, putting the Los Angeles Police Department and Los Angeles Fire Department in charge. The city set up a joint information center at the police emergency management center in downtown Los Angeles to operate during the closure. There, a traffic management team consisting of Caltrans, the California Highway Patrol, Metro, emergency response officials, and the Los Angeles Department of Transportation oversaw the operation from an upstairs room. At the same time, personnel from Caltrans and the California Highway Patrol observed the situation via cameras at the Los Angeles County Regional Transportation Management Center near Pasadena.

Downstairs, about 20 public information officers from local, State, and Federal agencies responded to calls from the public and media, and sent out frequent updates on Twitter, Facebook, and Nixle (a notification service for law enforcement and government agencies). At the same time, Caltrans kept a real-time watch not only on I–405 but on all of the freeways in Los Angeles and Ventura Counties from the agency’s transportation management center.

The Arrival of Carmageddon

And so it began. Ramps on I–405 began closing at 7 p.m., July 15, 2011, continuing through midnight as freeway lanes and connectors closed one by one. Media outlets had set up camp at a designated bridge site and were there reporting throughout the weekend.

As demolition proceeded, smoothly, it soon became apparent that the monster that would consume the city seemed to be asleep. In fact, Los Angeles County freeway traffic delays dropped 44 percent from the previous weekend, and vehicle-miles traveled dropped 12 percent. Just south of the closure, northbound I–405 traffic on Saturday, July 16, dropped 61 percent from the previous week and southbound I–405 traffic just north of the closure dropped 73 percent.

Los Angeles traffic had been scared straight! Motorists stayed off the freeways, the canyons, the streets, and all of the little shortcuts they would normally take. They rode bikes, walked to local attractions, or entertained at home. Some enterprising sorts even sold T-shirts and other memorabilia, while many businesses offered closure-related specials. JetBlue Airways invited Los Angelinos looking to get across town during the closure to take advantage of $4 flights each way from Burbank to Long Beach. In response, some bloggers challenged a group of bicyclists to a plane-versus-bike race from Burbank to Long Beach. The cyclists, who made the journey in about 1.5 hours, won the race, despite the short half-hour flight time, once the flight check-in and security processes were factored in.

Unfettered by traffic and encountering no unexpected issues, the contractor completed demolition and reopened the freeway to motorists at noon on Sunday, about 17 hours ahead of the estimated timetable. Instead of Carmageddon, some started calling it "Carmaheaven” and suggested making the closure an annual event.

Carmageddon II

Of course, Los Angelinos would have the opportunity to be carefree and go car-free again the following year, when Carmageddon II, as it was affectionately called, took place over the weekend of September 29–30, 2012.

As with the first closure, project staff knew the closure was coming, but again -- due to the flexibility and therefore slight unpredictability of the schedule in the design-build process -- were not sure exactly when. The timeline between the confirmation date and the closure turned out to be roughly the same as in the previous year. And, as before, public and media relations folks jumped into action.

The message this time was "eat, shop, and play locally,” initially delivered via press release on July 19, 2012, and followed by an interagency press conference 2 weeks later. Los Angeles Mayor Antonio Villaraigosa called Carmageddon I "truly one of L.A.’s finest moments” and exhorted the public not to become complacent based on the previous year’s low vehicle turnout. "We are again calling on the public to do its civic duty,” he said.

"I have every confidence [drivers] will rise to the occasion again,” said Los Angeles County Supervisor Yaroslavsky. "Let’s make this another Carmageddon-Schmarmegeddon experience for us all.”

Metro’s campaign emphasized alternative transportation options, offering special Carmageddon discounts of up to 50 percent at participating retailers to bus and transit riders. Numerous local businesses joined in with their own discounts linked to the use of public transportation over the weekend. Cooperation was particularly important during Carmageddon II because the work was more involved and early completion was unlikely.

Shortly before the closure, Caltrans debuted QuickMap, an interactive online tool and application that provides access to nearly 1,000 freeway cameras throughout the State and more than 700 electronic message signs. Site visitors could monitor traffic congestion, California Highway Patrol responses to incidents, travel-time information, road closures, and Amber Alerts. The application offered area motorists one more way to navigate around the closure.

The closure was implemented exactly as it had been before, with agencies again joining the police and fire unified command at the Los Angeles emergency operations center, establishing a 24-hour watch at the transportation management center, and deploying 30 additional electronic message signs. In addition to the demolition work, the closure presented a unique opportunity to perform 7 weeks’ worth of maintenance work elsewhere on the roadway segment in 48 hours. The work consisted of sweeping, clearing storm drains, inspecting bridges, sealing pavement cracks, restriping, replacing freeway signs, installing new raised pavement markers, and removing graffiti.

Carmageddon II went on without incident. Travel lanes reopened by late Sunday evening, around 7 hours ahead of schedule, providing more than enough time to prepare for the morning commute, which saw a return to traffic as usual. Los Angeles had done very well on foot, bicycle, bus, and train, roughly cutting in half the number of vehicles on the freeway.

The Power of Cooperation

Much like the reputed bliss of the 1984 Summer Olympics, when the sometimes unruly city was at its civilized best and its citizens united to provide visitors with easy access to all Los Angeles has to offer, Carmageddons I and II showcased the power of cooperation and partnership.

Caltrans and Metro partnered to build a much-needed carpool lane, law enforcement and emergency service agencies partnered with State and local transportation agencies to keep the city safe and functional during the unprecedented event, and members of the public embraced their responsibilities and stayed off the roads. What could have been a nightmare became a dream of life without traffic.

Carmageddon III, anyone?

Judy Gish is a public information officer for Caltrans in Los Angeles. Her background includes writing for several publications on a variety of transportation issues. She experienced Carmageddon firsthand and frequently finds herself on I–405 wondering if she will ever get home.

For more information, visit www.metro.net/projects/I-405/mulholland-dr-bridge-demolition-reconstruction or contact Judy Gish at 213–897–3487 or judy.gish@dot.ca.gov.