Freeway Quake Safety Testing Goes Slowly

Three years after faulty welding in San Diego freeway overpasses prompted a statewide review of 299 highway bridges for earthquake vulnerability, two heavily traveled interchanges near active faults in Los Angeles and Orange counties are only now being tested.

One interchange at the juncture of Interstate 5 and the Antelope Valley Freeway is the only spot in the state where highway bridges have collapsed in two previous temblors--the 1971 San Fernando and the 1994 Northridge earthquakes.

The other, the intersection of the Santa Ana Freeway and state highways 22 and 57 known as the Orange Crush, is one of California’s busiest interchanges.

Despite their proximity to faults, the two interchanges are among the last to be inspected and tested for welding defects--victims, Caltrans officials say, of limited resources.

New Caltrans Director Jose Medina said he was shocked to find out the review had taken so long and has ordered the department’s bridge engineers “to use all means at their disposal” to accelerate inspections and complete any necessary repairs.

“I’m very concerned that this review has dragged on for three years,” he said. “It is important that [it] . . . be completed as soon as possible.”

The state should have acted more quickly, Medina said, to alleviate any concerns that bridges might be unsafe in an earthquake, especially in seismically active areas that carry heavy traffic. “Our first . . . priority always will be public safety,” he said.

Caltrans Chief Deputy Director James Roberts, an internationally recognized bridge engineer, said preliminary inspections show the interchanges are safe from major damage, but officials won’t know for sure until welds are removed and tested.

He said the testing on the two interchanges will be completed by June and will not disturb traffic flow.

Tests of other overpasses throughout the state have uncovered welding flaws in at least 230 bridges, although officials say those defects are not serious enough to make the structures vulnerable to earthquake damage. Caltrans has, however, levied fines totaling $2.5 million against various contractors for sloppy work.

A towering web of highways that sweep over Mission Valley in San Diego to form the Interstate 805/Interstate 8 interchange remain the only structures in which welding defects were believed to be dangerous enough to require extensive repairs. The defects were uncovered in 1995, when suspicious state engineers ordered X-rays of bridge columns and footings that had just been retrofitted for earthquake safety at a cost of $44 million. The X-rays showed that most of the welds in the columns and footings supporting the interchange would fail in a 7.0 magnitude quake.

The welding scandal rocked Caltrans, prompting engineers to demand costly repairs to the San Diego interchange and revise their own procedures for inspecting steel welding. In addition, Caltrans’ then-Director James van Loben Sels ordered a statewide review of the welding on other bridges in seismically active areas.

Of the 299 bridges originally scheduled for review, 12 remain untested. Those include the seven bridges in the Orange Crush interchange, three in the Golden State/Antelope Valley freeways’ interchange and two on the Foothill Freeway near Hampton Road and Foothill Boulevard in La Canada Flintridge.

When Van Loben Sels ordered the statewide review, officials said, no deadline was set to finishthe inspections and no specific funds were set aside to pay for them. As a result, it was decided that to save costs, those bridges still under contract for construction or retrofitting would be tested first.

“We made a management decision to do it that way because the contractors were already there to do the physical work for us,” Roberts said.

That meant, he said, that on new bridges like those at the Golden State/Antelope Valley freeways’ and Orange Crush interchanges where construction had been completed, reviews would not be done until years later.

“If we had had the resources we could have done it faster but . . . we just did it based on the level of resources we had,” he said.

In the construction and retrofitting of bridges, steel bars welded together to form a continuous link are sometimes used to reinforce concrete columns and footings. If the welding is done improperly and is located in an area that would be highly stressed in an earthquake, it can fail.

To test the welds, technicians use water jets to strip away concrete and then remove a small section of the bar on each side of the weld. The section is then taken to a lab, where it is tested for strength.

A new bar, meanwhile, is welded into place as state inspectors watch.

The testing of welds is one of the last tasks to be performed by Caltrans in a decade-long seismic strengthening program that has become the most expensive bridge retrofitting effort in history. When the program is completed, the state will have retrofitted more than 2,200 bridges at an estimated cost of more than $4.5 billion.

Caltrans first began a limited retrofitting program after the 1971 San Fernando earthquake toppled overcrossings at the Golden State/Antelope Valley freeways’ and the Golden State/Foothill freeways’ interchanges.

But the real impetus for the seismic strengthening came in 1989, when the Loma Prieta quake caused the collapse of a long stretch of the Nimitz Freeway in Oakland and killed 42 motorists. In that same quake, a section of the San Francisco-Oakland Bay Bridge slipped off its supports, killing one driver.

In 1994, when the Northridge earthquake struck the Los Angeles area, seven bridges fell and Caltrans came under intense criticism for not moving faster with the retrofitting. Responding to the criticism, then-Gov. Pete Wilson announced that the program would be expanded and earthquake retrofitting would become Caltrans’ top priority.

Roberts said the program today is almost complete, with only 25 bridges--mostly in Northern California--left to go out for contract.

“I feel like I could stand under any bridge right now in an earthquake,” said Roberts, who is staying on the job long past retirement age to see the program finished.

“I feel so confident that I’ve told people I want some kind of celebration on Oct. 17, the 10th anniversary of Loma Prieta. I feel like a lot of people really busted themselves for this. A lot of overtime. A lot of hard work.”