Orange Crush Contains Faulty Welds, Caltrans Says

Bridges supporting the Orange Crush interchange--the fifth busiest in California--contain faulty welds that could fail in a Northridge-sized earthquake, and Caltrans is prepared to spend about $4 million to fix the problem, transportation officials say.

Problem welds--discovered by engineers during a statewide review of 1,100 bridges that began in 1996--are scheduled to be replaced beginning in December, disrupting traffic for the 189,000 commuters who on an average day drive through the crossroads of the Santa Ana, Orange and Garden Grove freeways.

The bridges, just 3 years old, are still sturdy enough to handle everyday traffic. Caltrans engineers and outside experts stress that even with a few bad welds, the bridges would not collapse in a moderate-sized earthquake.

“I would not be afraid to drive through [the interchange] during an earthquake,” said James Roberts, Caltrans chief bridge engineer. “You might have some damage, but you wouldn’t have a collapse.”

Yet tests earlier this year revealed that one in eight welds tested broke at pressures well below the design strength for resisting forces equal to a magnitude-6.5 earthquake. The Northridge quake was magnitude 6.7.

The presence of faulty welds raises a number of questions, including why the state approved the welds in 1995, why the problems were not corrected when first detected in 1997, why relatively new welds were so thin and brittle, who is responsible for repairing the shoddy work and how widespread the problem is.

“We don’t have enough evidence to determine the adequacy of the structures the way they are now,” said Phil Warriner, a retired Caltrans bridge engineer who is still part of the agency committee that has been investigating problem welds. “We’re trying to determine how large of a problem it is and what it would take to fix it.”

One contractor involved in the Orange Crush project said Caltrans inspectors and engineers have known for years that there might be problems.

“They saw everything that we were doing,” said Richard Guerrerio, former president of SGS U.S. Testing Corp., a Bay Area company that took industrial X-rays of many of the welds on the interchange. “This isn’t anything new.”

Problems in San Diego Start Statewide Review

Caltrans first learned that some bridges throughout the state might have faulty welds during construction four years ago of a San Diego interchange where the 8 and 805 freeways meet. That job was halted, and Caltrans demanded the contractor fix the flimsy welds--it reportedly cost $5 million to strip away the concrete and replace the bad welds.

The repairs were made, but several contractors are still haggling with Caltrans over who should pay for the fixes.

Welds are used to fuse together steel rebars to form hoops, like a giant Slinky, wrapped within the concrete bridge columns. During an earthquake, the hoops are supposed to trap broken chunks of concrete within the bridge column and maintain the support needed to hold up the structure until the columns can be repaired.

“The weld is very critical to the performance of the column,” said Frieder Seible, chairman of the department of structural engineering at UC San Diego and an outside Caltrans consultant. “It’s just as critical as the horizontal reinforcement. We’ve got to make sure the welds are not the weak link.”

Shaken by the extent of bad welds uncovered in San Diego, Caltrans vowed to make sure the same problem didn’t exist elsewhere in new bridges or those seismically retrofitted to withstand an earthquake. State engineers began scrutinizing 1,100 bridges built with the same type of weld used in the San Diego interchange.

During the statewide review of those bridges, engineers identified 299 for closer scrutiny. Eventually, Caltrans pinpointed several interchanges that needed more attention because the welds in question were in critical support zones. Engineers couldn’t be sure those welds were adequate, so they ordered some samples removed so they could be tested in labs.

Caltrans says they have ordered about $4.5 million in repairs to bridges with bad welds, not including the Orange Crush. Among those were some faulty welds found in an onramp to the new Century Freeway at Douglas Street, just south of Los Angeles International Airport. That problem was fixed in July.

Sometimes, engineers exposed welds that didn’t require repair. Those include two bridges on the Foothill Freeway in La Canada Flintridge, the intersection of the Foothill and the Glendale freeways near Burbank, and the interchange of the 5 and 52 freeways in San Diego.

Still under scrutiny, and of the greatest concern, are the Orange Crush, 4.3 miles from the El Modeno/Peralta Hills fault, and the Golden State/Antelope Valley freeway interchange near Santa Clarita, where 45 welds will be tested over the next 18 months and an assessment made of what to replace, said Jim Drago, Caltrans state spokesman.

The towering Santa Clarita interchange, which Caltrans’ officials also say will need some repairs, is in a precarious location. It’s the only spot in the state where highway bridges have collapsed in two previous earthquakes--Northridge in 1994 and Sylmar in 1971. The Sylmar temblor forced Caltrans to alter the design of bridges and begin retrofitting old structures.

The problem welds at the Orange Crush were installed during the two-year, $71.3-million program to improve the interchange and add carpool lanes. That job, which concluded in May 1996, was part of the more massive Interstate 5 widening project, a $1.6-billion effort that is supposed to wrap up next year.

Just a few months before the Orange Crush bridges were finished, in early 1996, Caltrans began its statewide review of bridge columns that contained the same type of weld found in San Diego.

But it took until mid-1997, more than a year later, for Caltrans to start examining the Orange Crush--even though Caltrans knew the same company welded the San Diego, Orange Crush and Santa Clarita bridges.

Caltrans has defended the time it took to get around to reviewing the Orange County interchange.

“We had 300 bridges to look at. Some of them had to be last,” Roberts said. “Besides, it was a newer bridge and we had every reason to believe that it was in good shape.”

First, Caltrans had to narrow the list of suspected bridges, which took about a year. Then they couldn’t find missing X-rays of welds in the Orange Crush. More than 1,000 X-rays were taken of bridge welds before concrete was poured. After a few months, Caltrans found just 286, and a third of those were so cloudy that they were of little use.

The process wasn’t speedy, Caltrans said, because the few engineers focusing on the weld investigation were also doing their regular jobs.

“We made a decision that this was not going to be treated as a five-alarm fire,” Caltrans spokesman Drago said. “We didn’t just drop everything to go in and do it. If we felt that there had been any danger, or that something was in danger of collapse, we would have moved quickly to close it. But that wasn’t the case.”

By April 1998, nearly a year since Caltrans first began examining the Orange Crush, Caltrans’ welding committee ordered that welds be cut from the columns of several bridges and that they be tested in a lab. They were still unsure whether the welds were a problem.

But it took another 10 months--until February 1999--for the testing to begin because of Caltrans’ slow contract approval process.

“We had problems getting contractors approved, and it’s a long process sometimes,” Roberts said. “Only a few companies do this type of work.”

Because few welds can be removed at a time from any one bridge column--to protect the structural integrity of the column--the work was slow. Finally, 56 welds were uncovered and removed. Seven fractured at pressures lower than the design strength.

Caltrans officials say the number of welds tested was too small a sample to draw broad conclusions about the structural integrity of the Orange Crush bridges.

Still, the agency believes the problems are severe enough that it plans to hire a new firm to do more tests and immediately replace bad welds--a job that could cost $4 million.

Lack of Funds Delays Repairs

It is taking another 10 months--from February, when testing began, to December, when repairs are supposed to be made--to make the fixes because Caltrans has been trying to find the funds.

“It’s just hard to find the money,” Warriner said. “There’s not just big pots of money lying around that we can grab onto.”

But, he said, the bridge welds will be fixed.

“Our goal is to get those structures back to where they need to be,” Warriner said. “The work will be done.”

Engineering experts based at UC Berkeley said that seven bad welds wouldn’t compromise a bridge’s ability to absorb tremors--unless faulty welds are in the critical support zone, the lower third of the bridge column near the footings. There are 2,400 welds in the Orange Crush bridges.

If welds in the support zone turn out to be faulty, “then it could be fairly significant,” said Jack Moehle, director of the Pacific Earthquake Engineering Research Center. “The bridge will have lost some of its seismic resistance. The welds are intended to provide continuity for the reinforcements.”

Caltrans places some of the blame on itself for the faulty welds, saying it should have been more diligent with its inspections during the initial construction of the interchange. But the agency says it was also busy inspecting hundreds of other bridges that were being seismically retrofitted and didn’t have enough qualified inspectors to go around.

“A lot of our field people, the resident engineers, did not have a lot of training in this area,” said Roberts, Caltrans’ top bridge engineer.

Adding to the confusion was a process--since halted--that allowed welders to hire their own inspectors, creating the potential for a conflict of interest. The agency now requires that general contractors hire a certified welding inspector for quality assurance.

“The process was seriously flawed,” Roberts said.

Contractors, and their attorneys, say Caltrans overreacted to the problems found in San Diego and launched an unnecessary statewide review that has uncovered few bad welds. After all, they say, Caltrans inspectors approved the very welds they are now questioning.

“What was a good weld yesterday is now a bad weld,” said John Gladych, a Newport Beach attorney who represents Jesse Mejia, owner of Mejia Steel Welding in Riverside County, the welder for the Orange Crush, San Diego and Santa Clarita bridges. “This is a clear case of someone trying to change the rules after the game has been played.”

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Bracing for the Big One

Caltrans engineers acknowledge that freeway bridges at the Orange Crush interchange in Santa Ana and the Golden State/Antelope Valley interchange in the San Fernando Valley have faulty welds that could fail during a significant earthquake. Welds were also tested and repaired recently on Southern California bridges with similar problems. How bridges are designed to react during a quake:

“Plastic Hinge” allows bridge column to bend during quake without falling at roadway and footing connections.

Spiral hoops prevent column from collapsing during quake by containing cement core.

Vertical bars can buckle if hoop weld fails, causing column to collapse.

Vertical metal bars support roadbed weight, connect column to footing.

Concrete footing provide greater support in soft soil.

Tie-down rods bore deep into ground.

Testing Welds

Golden State/Antelope freeway interchange: weld problems suspected.Source: Caltrans, Pacific Earthquake Engineering Research Center

Graphics reporting by BRADY MacDONALD / Los Angeles Times