Unprecedented Teamwork Repairs Collapsed Freeway in Record Time

Tanker Explosion Collapses Section of California Freeway
Published 10-2-2007
  • Better Than New

    In less than a month, repairs to the MacArthur Maze were completed. Caltrans and its contractors developed innovative and creative solutions based on years of experience and knowledge to cut time without compromising quality.

    Photo courtesy of Caltrans Photo Department.

  • Bent Cap

    This new 55-foot, 120-ton bent cap was delivered and installed in less than three weeks from the original date of the explosion.

    Photo courtesy of Caltrans Photo Department.

  • Tanker Explosion

    A tanker truck carrying unleaded gasoline crashed and burst into flames on a section of California freeway known as the “MacArthur Maze”. Intense heat from the fire caused the upper deck of a connector ramp to collapse onto the lower deck.

    Photo courtesy of Caltrans Photo Department.

The images were horrifying. A gasoline tanker truck exploding into a fireball. A freeway connector ramp collapsing into a cloud of flames and hot cinders. More than 160 feet of roadway completely missing from the upper deck. Twisted, fire-blackened girders on the lower deck.

San Francisco Bay Area residents awoke to these images on April 29, 2007, and feared the worst. Surely it would take months to repair the ramps. Just as surely, the damage would cause massive traffic jams. After all, these two ramps were integral parts of the interchange known as “The Maze,” one of the most vital and heavily traveled interchanges in the SF Bay Area. The Interstate 580 connector ramp—the upper deck—carried traffic from San Francisco to Oakland, Walnut Creek, and points east. The Interstate 880 connector—the lower ramp—carried vehicles headed from Sacramento to San Jose and further south. Bloggers and talk radio hosts gloomily predicted months of gridlock and misery.

Yet it didn’t happen. In just over one week, the fire-damaged lower deck was re-opened to traffic. In less than a month, the upper deck was back in business.

Bay Area residents were more than just surprised. They were astonished. Some were openly skeptical. How could such damage be repaired so quickly? Were corners cut? Are the ramps safe?

No corners were cut. The ramps are safe. In fact, they are in better shape now than when they opened. The rapid repair was a combination of ingenuity, teamwork, and old-fashioned hard work.

Within minutes of the accident, Caltrans maintenance workers and the California Highway Patrol closed the damaged sections. Temporary detour signs were set in place. Caltrans District 4 Director Bijan Sartipi activated the Emergency Response Center. Caltrans Director Will Kempton was on the scene within a few hours, and briefed Governor Arnold Schwarzenegger by phone. A short time later, the Governor issued an emergency proclamation.

Expedited Contracts

The proclamation permitted Caltrans to award emergency contracts. A specific order by Director Kempten is a state-authorized document allowing Caltrans to by-pass normal contracting procedures and to quickly initiate and complete emergency work sooner than the conventional process.

Before any other work could be done, the collapsed section of roadway had to be removed. A demolition contractor would have to be found and hired as soon as possible. As they ran down the names of demolition contractors, Caltrans had its first bit of luck.

Just across the bay in San Francisco, Cleveland Wrecking Company was at work demolishing the old sections of the Bay Bridge West Approach. Cleveland Wrecking is on a Caltrans list of pre-approved contractors that are available for emergency projects. Caltrans awarded the emergency contract to Cleveland Wrecking because it had the most equipment and personnel closest to The Maze. Within minutes, Cleveland broke crews and equipment away from the West Approach and sent them over to The Maze. The demolition crews got right to work, even though the heat of the morning’s fire could still be felt.

Caltrans engineers also felt the heat as they inspected the remaining portions of the I-580 connector. They took steel samples from the surviving girders and the attaching hardware. The bent cap had collapsed with the roadway, and would have to be replaced. The bent cap is a 55-foot long concrete or steel bar weighing 120 tons. It sits on top of concrete columns and serves as a base for the roadway. The columns supporting the bent cap and roadway still stood, but were blackened by the fire, and would have to be closely inspected.

While the engineers in the field performed their inspections, their colleagues in Sacramento and the Oakland district office pulled the original drawings out of the files, and got to work designing a replacement ramp for the 580 connector. They made one significant change. The original bent cap was made of steel. On the other hand, concrete and rebar bent caps could be manufactured much more quickly, and were more fire-resistant. The design team fired up their computers, and set to work on the drawings for a concrete and rebar bent cap.

A few floors down, the Emergency Response Center (ERC) operated at full boil. Caltrans executives had called key personnel earlier in the morning, and told them to report to the ERC at once. Other Caltrans staffers simply showed up, and asked to be put to work. Workers from Maintenance and Traffic organized the detours. Administration cranked out a series of emergency expenditure authorizations, as allowed by the Director’s Order. A contractor, American Civil Constructors, was hired to coordinate traffic control, and to start preliminary work on the 880 connector ramp. Representatives of the City of Oakland and the Governor’s Office of Emergency Services soon joined the team.

Avoiding Gridlock

As news of the freeway collapse spread, reporters from all over the country called the Caltrans Public Information Office. The most commonly asked question was, “How bad will traffic be tomorrow?” By late afternoon, the Governor provided a partial answer. In order to encourage the use of public transportation, the state would pick up the tab for a “free transit day” on Monday, April 30. All forms of public transportation—buses, ferries, and the Bay Area Rapid Transit rail system—would be free. Transit operators promised to have additional buses and trains ready.

Work continued through the night, and into Monday morning. As the morning commute approached, Caltrans staffers listened closely to the morning news. They hoped the gridlock wouldn’t be too bad, but realized that even with the free transit, traffic would probably be a commuter’s nightmare. When the first traffic reports came in, the news was almost unbelievable.

Traffic was moving smoothly. There were hardly any backups. Buses, trains, and ferries ran at full capacity. Those who didn’t use public transit altered their normal routes, and stayed away from The Maze. The predicted gridlock failed to materialize. The “free transit day” was an unqualified success.

By late afternoon, Cleveland Wrecking finished removing the collapsed roadway. With the debris cleared way, engineers could start examining the 880 connector ramp. Steel samples were taken from the girders, and core samples were drilled out of the concrete roadway. The steel was sent to the Caltrans Materials Lab in Sacramento. The concrete samples were handed over to a consulting firm, Wiss, Janney, and Elstner, for evaluation at their lab in Texas. Steel and concrete samples were also drawn from the 580 ramp’s supporting columns.

The Race Is On

Within a day, the results of the steel tests came back, and the news was good. While the fire had warped and twisted the 880 girders, the structural integrity had not been compromised. The girders could be straightened. While that was no easy task, it was infinitely preferable to the scenario of tearing down the entire structure. The core samples of the concrete deck showed quite a bit of damage, but it, too, was repairable. On Wednesday, May 2, Governor Schwarzenegger made the official announcement—the 880 connector ramp would be fixed and open to traffic within seven to ten days. American Civil Constructors huddled with Caltrans engineers and got to work.

Caltrans had already custom-designed the external bracing—the “falsework,” cutting several days off the schedule. Crews then started installing the falsework. Once the freeway was properly supported, crews could start fixing the first of many problems—the uneven road surface.

When the heat of the fire warped the girders, the roadway became twisted out of shape, resulting in a nine-inch dropoff between sections. Caltrans and the contractor brought in a set of hydraulic jacks and lifted the entire structure nine inches, bringing the roadway back into alignment. Once the deck was realigned, the relatively normal task of deck rehabilitation got underway. Damaged concrete was ground out, new concrete was poured, and damaged barriers and electrical components were replaced.

Down below, a more unconventional job was underway. The girders would be fixed with a process called “heat straightening.”

“It’s a bit like acupuncture,” explains Caltrans project manager Skip Sowko. “Acetalyne welding torches are brought in, and a certain amount of heat is applied for a certain time to a certain spot. Once the steel has been heated to the proper temperature, hydraulic jacks straighten the girders.”

The heat-straightening was anything but a cut-and-dried process. Fortunately, the falsework could assume most of the structural loads. The ramp could be open to traffic while workers continued the straightening process.

That happened more quickly than anyone expected. On May 2, Governor Schwarzenegger said the work would take seven to ten days. It took even less time thanks to an increased number of workers, a 24/7 schedule, and a healthy dose of good luck. At just after four in the morning on May 8, the 880 connector ramp was opened to traffic. Caltrans even added a special feature to the reopened ramp—the deck had a brand-new overlay of durable polyester concrete. Car and truck drivers were once again able to drive straight from Sacramento to San Jose with no detours, while just below, workers continued to straighten the girders.

There was another major announcement on May 8. Caltrans Director Will Kempton awarded the contract to rebuild the 580 connector ramp. The previous week, while the 880 repairs were underway, Caltrans engineers worked around the clock to finish the design of the rebuilt 580 interchange. While the 880 project was awarded as an emergency contract, Caltrans put the 580 job out to a limited bid. On Friday, May 4, Caltrans released the design and invited only nine contractors to submit bids. These nine companies were chosen for their experience in bridge-building. The bidding closed the following Monday morning, with seven of the nine companies submitting bids. The next day, Caltrans awarded the contract to C.C. Meyers, Inc., of Rancho Cordova, Calif., near Sacramento.

At first, reporters were astonished by Myers’ bid, just $867,075. Caltrans had estimated the cost of the project to be about $5.2 million.  How on earth could Myers build the new ramp for less than a million? The steel itself would cost at least that much.

Director Kempton explains, “The contract called for a work schedule of fifty days.  However, for every day the project finished early, the contractor would earn a bonus of $200,000, with a cap of $5 million.”

Myers confidently told the press he intended to earn every cent of the $5 million. So confident, in fact, that he began moving people and equipment into place even before the contract was awarded. His bid of $867,075 was simply the remainder of the price.

Myers and Kempton signed the contract around four p.m. on May 8. Less than an hour later, Myers’ staff was on site, ready to start work. A great deal of time was saved since the project was only reconstruction and repair of the burned section. The only new design elements were a bent cap--now made of concrete and steel rebar--and new girders designed for quick construction.

The first task was the columns. Again, the news was good. The steel and concrete samples showed some minor damage to the concrete and grout in the top four feet of the columns. Myers workers brought their equipment into place, and got to work grinding out the top four feet of concrete and steel rebar.

Myers quickly hired two subcontractors. Con-Fab, of Lathrop, Calif., got the job of building the new bent cap. Stinger Welding, of Coolidge, Ariz., was tapped to build the new girders. Stinger made calls to specialty steel mills in Sewickley, Pa., and Houston. Within a few days, the steel was on its way to Arizona. Myers told Stinger to hire two truck drivers for each rig hauling the steel. Although two drivers per rig cost more, they could spell each other, and drastically cut the delivery time.

Caltrans sent engineers and inspectors to Arizona to assist with and monitor the fabrication. Stinger Welding President Carl Douglas was surprised, but impressed.

“Caltrans came in and put good people in the shop. If there were any problems, we could go to them and get immediate answers. It was a breath of fresh air to have a government agency come in and perform like that,” says Douglas.

The head of Con-Fab, Philip French, was also impressed. “I take my hat off to Caltrans,” he says. “They have been very proactive, and just great to work with.” As was the case with Stinger, Caltrans engineers had the shop drawings in Con-Fab’s hands within 24 hours of the contract award.

Sunday, May 13, was Mother’s Day, but the Con-Fab employees arrived at the Lathrop yard before sunrise for a full day of work. The steel rebar was securely in place inside the wooden formers. The concrete was ready to pour. Truck after truck poured concrete into the wooden formers, and vibrating machines made sure no air bubbles formed. Then, the concrete was covered and all left to cure.

Two days later, the 55-foot long, 120-ton bent cap was ready for delivery. A massive, 30-axle tractor trailer rig was brought in to haul it from Lathrop to Oakland. As the truck slowly made its way along the highway, the local news media closely followed the trip. There were so many news helicopters in the air, one Caltrans engineer commented, “It looked like the O.J. Simpson chase.” After a three-hour trip, the tractor trailer parked on the 880 connector ramp, which had been closed for the evening’s operation. As news helicopters continued to hover overhead, cranes slowly lifted the bent cap off the truck, and gently set it atop the columns. It was a perfect fit.

A short distance away, in Vallejo, Calif., painters were spraying primer on the first of the brand new girders to arrive from Arizona. Although the priming was a necessary step, the workers were initially a bit reluctant to start painting. Someone at the Stinger Welding yard added a touch of heartfelt graffiti to the first girder. It read, “To the people of Oakland--with love, your friends in Arizona.”

The next night, Wednesday, May 16, trucks hauled two of the newly-painted girders to The Maze. Once again, the crane operators performed their magic, and the girders were smoothly lifted into place. Over the next several nights, the rest of the girders—12 in all—made the trip from Vallejo to Oakland. The final two were set in place early Sunday morning, May 20. That afternoon, the new deck was ready to pour. Several news reporters were astonished. How could concrete be ready to pour the same day?

The usual practice is to perform one job at a time. C.C. Myers worked out a schedule that allowed several jobs to be done at once. Two crews worked twelve-hour shifts. The moment the first girders went in, the diaphragms and wooden formers were added. Once the wooden formers were ready, additional workers were brought in to start assembling the rebar. As more girders went in, more formers and rebar were added. Once the last of the girders was installed, it took only a short time to add the last of the formers and rebar. A few hours later, trucks were hauling concrete to the site. Inspections conducted on a 24/7 scheduled helped to keep the process moving smoothly.

Myers and Caltrans chose a special type of concrete called “High Early Strength Concrete.”  After pouring, water hoses regularly moistened the concrete in order to keep it from drying too quickly. By alternating between moistening and drying, the concrete becomes much stronger.

Final Touches

While the concrete cured, workers finished the odd jobs: fixing the barrier rails, replacing the damaged electrical wiring and hardware, and cleaning up the work site. Everyone—the workers, the reporters, and the traveling public—knew it was the home stretch. Caltrans announced the road would open sometime before the morning commute on Friday, May 25, Memorial Day. There would be no ceremony. All involved, from the Governor on down, agreed that the patient Bay Area commuters should not have to endure the delay of an ostentatious ceremony. The ramp would open as soon as it was ready.

At 7:30 p.m. on Thursday, May 24, eastbound traffic was held on the Bay Bridge while the workers uncovered the traffic signs and removed the cones and barriers. Just over an hour later, at 8:40 p.m., the ramp was opened. A television crew in a mobile news van tried to be the first to cross over the repaired ramp, but was beaten at the last moment by a swift motorcycle.

The next morning, the Oakland Tribune headlined the story with the words, “It’s Open!” The San Francisco Chronicle countered with “A-Maze-ing!” Defying all odds and gloomy predictions, the ramp opened less than a month after the accident.

How did it happen? It was a combination of things. Both Caltrans and its contractors drew on their years of experience and knowledge. All involved sought innovative and creative methods to cut the construction time without compromising quality. Government officials set aside partisanship and gave Caltrans unqualified support. Everyone worked hard, many putting in 14 to 18 hour days.

Perhaps the late Speaker of the House, Tip O’Neill, said it best: “You can accomplish anything when you don’t care who gets the credit.” The project was totally free of squabbling, ego clashes, and turf battles. Almost from the first moment, Caltrans and its contractors were determined to turn a horrific accident into the project of a lifetime, something in which everyone could take pride. From all appearances, they succeeded.

Reprinted with permission copyright © 2007 California Department of Transportation District 4, State of California.

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