O.C. Freeway Structures to Be Reinforced

By JEFFREY A. PERLMAN and JEFF BRAZIL

Jan. 19, 1994 12 AM PT

TIMES STAFF WRITERS

Like the 11 elevated highway sections toppled by Monday’s earthquake in Los Angeles County, several of Orange County’s busiest freeway overpasses run the risk of collapsing in a major earthquake, but officials said work is underway--or scheduled--to fix them.

The top priority now is the interchange of the San Diego and Costa Mesa freeways near John Wayne Airport, where work begins this month.

Of Orange County’s 500 freeway structures, 80 have been identified as posing some risk and are included in the state’s retrofit program. Seven reinforcement projects are underway and 12 more projects involving 48 structures are scheduled to begin this year, according to California Department of Transportation spokesman Albert Miranda.

The county’s freeway structures are mostly of newer design and don’t need to be “retrofitted” with extra support to minimize earthquake damage.

The county’s two most vulnerable highway structures--near the interchange of the San Diego and San Gabriel River freeways--were reinforced after the 1989 Loma Prieta quake in the Bay Area, according to Caltrans.

Retrofitting is also underway as of the installation of car-pool lanes on the Riverside Freeway where it crosses the Santa Ana River.

Most of the remaining retrofits are also being scheduled to coincide with other freeway improvements, such as the massive Santa Ana Freeway widening project, in order to avoid changing things twice, Caltrans officials said.

Caltrans launched a major program to inspect overpasses, bridges and highway interchanges after the disastrous Loma Prieta earthquake, when a double-decked segment of an interstate highway pancaked on a stream of rush-hour traffic in Oakland, sending the quake’s death toll soaring.

Medhat Haroun, chairman of UC Irvine’s civil and environmental engineering department, said that to the best of his knowledge none of the elevated highway structures that had been reinforced under the state’s 5-year-old retrofitting plan had collapsed in Monday’s quake, and this showed how important it was to carry on with the program.

“The bridges and overpasses will stand if they are retrofitted,” he said. “But the only thing is, they should hurry up.”

Tim Buchanan, a Caltrans project manager, said Caltrans engineers do not hesitate to issue change orders to get the latest and safest technology for ongoing projects, as they did on reconstruction of the Santa Ana-Garden Grove-Orange freeways interchange, where the contractor was told to add more reinforcing steel to decks and their supports.

And the same order went to contractors rebuilding other segments of the Santa Ana and Costa Mesa freeways, as well as the junction of the Santa Ana and San Diego Freeways, known as the El Toro Y.

But, warns Frank Weidler, Caltrans’ deputy director for construction in Orange County: “There’s no such thing as an earthquake-proof structure.”

“At ground zero,” said Weidler, “you’re going to have a problem.”

Weidler said unmapped faults also pose a risk. “We look at the maximum credible earthquake from the faults that we know about” in designing the retrofits.

“We’ve gone through and attacked this thing in a priority fashion, and we’ve retrofitted those structures (statewide) that were in imminent danger of collapse” in an earthquake, Weidler said. “I’m not particularly concerned about the structures (yet to be retrofitted) in Orange County.”

Weidler explained that few if any structures here are based on old, single-column support designs.

Keith E. McKean, former Caltrans district director and now a consultant, agreed that the Northridge quake shows that new technology works. The Century Freeway survived; the Santa Monica Freeway collapsed. It hadn’t been retrofitted.

“There are still several structures in Orange County that need to be done,” McKean said. Taller structures are the most important, he added, because “they’re subject to the most shear forces.”

Still, guaranteeing structural survival would require a money-is-no-object approach, transportation experts agreed.

“You can design a structure to withstand any earthquake, but you have to be willing to pay for it,” said UCI’s Haroun. “You can build to withstand (a magnitude) 8, but the expense is prohibitive. So what you do is you design it so if it’s a 7, there will be some damage, but no collapse.

“Let me give you an analogy,” said Haroun. “If I tell you to buy a car and money is no object, you go out and buy a Porsche. If I tell you to buy a car that will serve all of your needs, that will get you to work every day, you don’t need a Porsche. The Porsche is available. It’s out there. But you usually don’t need it. Now if you’re building a nuclear reactor or natural gas facility, you buy the Porsche . . . the consequences are great.”

Haroun said most freeways, bridges and overpasses in Orange County would withstand a quake similar to Monday’s temblor.

But he cautioned that it’s the Newport-Inglewood Fault along the coast that poses the biggest threat, not the much-vaunted San Andreas fault out in the desert.

“We can get potentially more damage from a magnitude 7 on the Newport-Inglewood than an 8 on the San Andreas,” which is much farther away, Haroun said.

Added Haroun: Monday’s quake may serve a useful purpose if it reminds the Legislature of how much work remains.

“Memory about earthquakes is very short,” Haroun said. “After a year or two, everybody says, ‘Well, we have other things to worry about.’ I think that was about to happen.

“Caltrans seized the moment after the Loma Prieta earthquake and they got the money for retrofitting. But I think if Caltrans had gone to the Legislature now and said they needed more money to do more retrofitting, the Legislature would have looked at the budget and said, ‘Well, we have more pressing needs.’

“An earthquake every few years is good to remind people that this is a continuing problem that we need to be concerned about.”

Unfortunately, he added, the wake-up call comes “too late for the Santa Monica Freeway,” which was due to undergo retrofitting next month.

McKean, the former Caltrans district director, said projects such as the El Toro Y probably will not face delays because they have already been funded and are underway.

Instead, the tremendous financial burden of quake repair work may threaten projects that have not yet started, McKean said.

“As a result of what’s happened they’ll probably be looking at everything in terms of reorganizing priorities,” McKean said. “And there simply isn’t enough funding there to do everything and there’s a lot of rebuilding that has to be done in L.A. County.”

Meanwhile, Caltrans announced Tuesday that it has completed a preliminary inspection of all bridges, overpasses and freeway construction projects on Orange County freeways in the wake of Monday’s quake, and pronounced that all are open and safe to travel.

Seismic Retrofitting

On seven Orange County freeways, 48 structures in 36 locations will be reinforced so they can better withstand an earthquake. The work will include outfitting with steel jackets or metal rods.

SAN DIEGO FREEWAY

* Two connectors to Costa Mesa Freeway

* Overpass at Talbert Avenue

* Overpass at Warner Avenue

* Overpass at Magnolia Street

* Overpass at Newland Street

* Overpass at Brookhurst Street

* Overpass at Ward Street

* Overpass at Seal Beach Boulevard

SAN GABRIEL RIVER FREEWAY

* Two underpasses at Katella Avenue

* Three interchanges with San Diego Freeway