EARTHQUAKE / LIFELINES OF L.A. : THE QUESTIONS : Shaky Bridges, Shaken Theories : When the violent shaking started, John Faust was already on the freeway, driving Metropolitan Transportation Authority bus No. 3466 through the crisp morning darkness.

Powerless to prevent his 14-ton vehicle from jerking half a lane to the right, Faust braked to a heart-pounding stop. Then he swung the 40-foot bus sideways--blocking oncoming drivers from what only he and a handful of others could see:

A gaping chasm in the eight-lane Simi Valley Freeway, where it once crossed San Fernando Mission Boulevard.

“It was like looking down into a pit, a void,” said Faust, whose bus was not carrying passengers. “My thought was: ‘Am I going to get out of here safely?’ ”

He and the others did make it out, aided by providence of the Northridge earthquake’s 4:31 arrival. Had the temblor hit two hours later, this and the region’s other freeways would have been loaded with traffic.

But the failure on the Simi Valley Freeway is larger than just the loss of one important traffic artery.

Of the six major roadway collapses caused by the Jan. 17 earthquake--of the 157 other overpasses damaged--the Simi bridge’s failure remains perhaps the most unnerving: It defied some of the most modern engineering assumptions used to safeguard California’s freeways from earthquakes.

“(The bridge) contains a lot of the details that we like to see in designs--and yet it still performed poorly,” said UC San Diego’s M.J. Nigel Priestly, the research leader for the state’s program to fortify freeways.

California Department of Transportation officials decided earlier this decade that the structure was not at risk. Overruling two junior engineers, they removed the bridge from the list of structures scheduled to be “retrofitted” with jackets of steel reinforcements, records show.

Now the collapse has called into question the standards Caltrans has used to determine which bridges get retrofitted and when. As a consequence, the safety of hundreds of similar bridges excluded from the list is being re-evaluated.

“The good news from this earthquake is that retrofitting worked,” Priestly said, noting that not a single retrofitted bridge suffered serious damage.

But the performance of the Simi Freeway and the collapse of other roadways, which caused about $1.5 billion in damage and left a motorcycle patrolman dead, shook confidence in the safety of the nation’s most intricate network of freeways.

It also raises this question: Four years and four months after another earthquake crushed to death 43 motorists on two San Francisco-area freeways, with what urgency have California’s engineers and political leaders sought to strengthen hundreds of other bridges identified as being seismically unsafe?

A Times examination found that the pace of a state program to retrofit freeway bridges and overpasses has been slowed in part by cost concerns, competing transit projects, Caltrans’ cumbersome bureaucracy and a public employee union’s lawsuit.

Records and interviews also show:

* About 80% of the state’s 1,313 bridges identified as being vulnerable to earthquakes have not been repaired.

* In Los Angeles County, 84% of 716 bridges designated for retrofitting remain unrepaired.

* Only four of the 10 most vulnerable overpasses in the county have been fixed--and the unrepaired spans are at some of the busiest freeway junctures.

* Caltrans has spent less than a third of the $300 million per year that officials estimated would be used for shoring up unsafe bridges.

* A small share of the billions of dollars from a new gasoline tax has been spent on bridge repairs, although voters were told that seismic retrofitting would be a major beneficiary of the new revenue.

* And, just three days before the Northridge quake, the director of Caltrans halted the hiring of outside engineering consultants who have performed nearly half the design work for the bridge retrofitting program.

Caltrans officials say they have moved as swiftly as possible, considering the complexities of the work. Although more retrofitting needs to be done, they said the state’s bridges are generally sound.

“I think they’re very safe, but we have some work to do, to get a few bridges up to the standard of the rest of them,” said James W. van Loben Sels, who was appointed to head Caltrans by Gov. Pete Wilson. “We’re going to do it as rapidly as we can.”

Chief Caltrans bridge engineer James E. Roberts said the retrofitting program has moved cautiously to ensure that the costly repair procedures would work in the real world, not only in a laboratory.

Roberts said he wants the same emergency powers for retrofitting that the governor has given the agency to rebuild the damaged freeways. However, Van Loben Sels said he does not believe emergency powers are needed.

The decision Jan. 14 to halt outside contracting for design engineering work will not slow the retrofitting program, according to Caltrans spokesman Jim Drago. He said the decision was made for cost reasons and that the department’s in-house staff of engineers can shoulder the extra workload.

“This is our highest priority and other projects may feel delays because of that,” Drago said.

Two years ago, Caltrans completed an analysis of the state’s 12,000 bridges, concluding that 4,000 posed varying seismic hazards. Since then, the retrofitting list has been whittled down to 1,313.

Caltrans officials take 17 factors into account when ranking bridges, including the proximity of earthquake faults, traffic volume and age. Structures built before 1950 or after 1980 are considered the most sound.

Work has not been completed on some of the most unsafe bridges, officials said, because many are supported by clusters of columns--and a higher priority has been given to fixing single-column bridges.

Caltrans had assumed that the single pillars were the most vulnerable. But the Northridge quake crumpled both types of columns.

“The multicolumn (bridges) have to be a higher priority than they were before,” said Ronald Mayes, a consultant to the National Center for Earthquake Engineering Research in Buffalo, N.Y. “Some of them are very vulnerable.”

A Race Against Time

To appreciate how far California has come, or not come, in building bridges to survive quakes, it is helpful to recall how fortunate the state has been until recent years.

“Before 1971, California only lost $100,000-- total, in history --to bridge damage from earthquakes,” said Brian Maroney, senior bridge engineer for Caltrans’ Office of Earthquake Engineering.

That year the 6.4 Sylmar earthquake toppled parts of two interchanges, killing two men in a pickup truck. They died less than two miles from where LAPD Officer Clarence Wayne Dean would plunge to his death from a freeway bridge on Jan. 17, 1994.

After Sylmar, Caltrans set about rebuilding the interchanges and fixing 58 damaged overpasses. As a precaution, they outfitted about 1,200 overpasses with cable restrainers to keep segments of roadway from separating and collapsing.

Knowing that scores of bridges passed the test of the Sylmar quake, Caltrans officials may have been “lulled into a false sense of security,” said James H. Gates, head of structural mechanics engineering for Caltrans.

Over the next 16 years, the significant quakes that struck the state were either in rural regions or did not inflict damage to major roadways. It was not until October, 1987--when the 5.9 Whittier quake stunned engineers by nearly toppling the two-level interchange of the Santa Ana and San Gabriel River freeways--that an intensive research effort was launched.

Caltrans engineers began seeking to identify vulnerable bridges and studying what repairs could be made, short of tearing down and rebuilding thousands of structures.

Then came Oct. 17, 1989. The World Series game in San Francisco that wasn’t. The grisly footage of the collapsed, double-deck Nimitz Freeway that killed 42 people--an inadequate design made lethal by the Loma Prieta earthquake.

“Most of California’s reinforced concrete bridges were designed and built before the 1970s and their seismic performance is suspect,” warned a governor’s Board of Inquiry into the Loma Prieta quake. But has government’s response come close to matching the dangers highlighted by the Board of Inquiry’s May, 1990, report, “Competing Against Time”?

“There is pretty strong evidence that this retrofitting program is working,” said Jack P. Moehle, a UC Berkeley professor and director of the nearby Earthquake Engineering Research Institute. “Unfortunately, nature has just moved a little more rapidly than Caltrans.”

Richard Katz, a San Fernando Valley legislator who chairs the Assembly Transportation Committee, said: “Caltrans has an inherent problem, internally, of (not) being able to do anything quickly.”

Indeed, Caltrans’ pace of retrofitting has not matched either the department’s estimates or the promises made to voters by an array of leaders.

In 1990, the bipartisan promoters of a sweeping transportation ballot initiative, Proposition 111, told voters that if they would agree to double the state gasoline tax, the earthquake-retrofitting program would be a major beneficiary.

The tax has doubled--from 9 cents a gallon in 1990 to 18 cents a gallon today--raising about $1.4 billion more a year for overall transportation projects.

But records show that from mid-1989 to July of this year, Caltrans will have spent $432 million to retrofit 251 bridges--amounting to an average of 3% of the agency’s overall annual budgets. The spending for retrofitting is less than a third of the $300 million a year that then-Caltrans Director Robert K. Best told the Legislature in 1991 he hoped to spend.

Jack McDowell, a consultant who managed the Proposition 111 campaign, said, “If somebody broke their promise (afterward), we had no inkling during the campaign.”

Asked why the department has spent only $86.5 million a year on retrofitting, Caltrans’ Roberts said the repair procedures had to be adequately researched and soil conditions sometimes required years-long analyses.

Building can also be difficult, he added, because some jobs require lane closures, night work and approvals from other agencies.

Litigation also has delayed some work. Eight private engineers said in interviews they were ordered by Caltrans to stop retrofit designing because of a lawsuit brought by the union for the department’s engineers. The stoppage for several months last year came after a judge’s ruling in favor of the union, which has sought to block the hiring of outside engineers.

A bigger bottleneck, according to a former Caltrans official, is the agency’s contracting procedures. It has taken as long as a year to get approval to retain outside engineers. “We had to go through the same process as purchasing toilet paper for state toilets,” said Herbert K. Jensen, who until late 1992 administered the contracting.

Before last month’s quake, the department had planned to spend $1.1 billion more to repair about 1,000 bridges that remained on the state’s retrofitting list.

If, as expected, dozens more bridges are identified for retrofitting in the coming weeks, Caltrans spokesman Drago said these projects would also “get first crack” at Caltrans’ pool of money. At least $615 million more will be needed for seven of the nine toll bridges maintained by Caltrans and additional funds will be necessary for the 13,000 overpasses and toll bridges controlled by local governments.

During the last four years, the administrations of two governors and state legislators of both parties have said with voices and votes that retrofitting should receive top priority. In practice, state Sen. Tom Hayden (D-Santa Monica) said, it has not worked out that way.

“There are always developers and politicians lobbying for a new off-ramp, or some other project,” Hayden said. “(Caltrans) can’t move forward faster with retrofitting without cutting into those projects.”

Dean R. Dunphy, Gov. Pete Wilson’s secretary of business, transportation and housing, acknowledged the intense competition for Caltrans funding. “Retrofitting has been a priority from the beginning,” Dunphy said. “But not the only priority.”

Bruce Nestande, a past chairman of the California Transportation Commission, said safety also has been at stake when Caltrans spent money for items unrelated to retrofitting, such as widening freeway on-ramps. “A decision was made not to shut everything else down for the motoring public,” he said.

Assumptions Crumble

One of the most encouraging lessons that engineers say they have learned from the Northridge earthquake is that retrofitting works:

Field investigators have confirmed that the 115 retrofitted overpasses in Los Angeles County were unscathed or had minor damage. None had to be closed.

But interviews and records show that at least four of the quake’s six major bridge collapses challenge the engineering assumptions and policy decisions dictating whether or when bridges get fixed:

* Simi Valley Freeway overpass, at San Fernando Mission Boulevard/Gothic Street: When Caltrans re-evaluated the list of bridges planned for retrofitting three years ago, engineers overruled recommendations of two subordinates and decided that the Simi Valley structure was safe. The bridge was removed from the list.

Now, the decision is open to doubt. Subjected to 12 seconds of some of the most intense ground shaking inflicted on any structure during the Northridge quake, the 566-foot-long bridge failed. Engineers said the 10 concrete support columns turned out to be too stiff.

Roberts of Caltrans defended the decision to remove the bridge from the retrofit list, saying it was based on the best information available at that time. “I think that was a good judgment, personally,” he said.

The bridge was removed from the list in part because it was designed in 1973, with the benefit of lessons learned from the 1971 Sylmar earthquake, officials said.

Engineers who have studied the collapse have found a clue that may help prevent others. They believe that the failure of the steel-reinforced, concrete columns was hastened by what was once an award-winning architectural feature: The tops of each of the columns had a gradual Y-shape, called a flare.

These flares, according to the engineers, decreased the flexibility of the columns. Designers had assumed that the top edges of the flares would merely crack and crumble during a strong earthquake--without doing harm to the overall integrity of the column. Instead, the Simi Valley Freeway overpass flares remained intact, placing more strain on the columns.

“They were conceived to be primarily aesthetic,” said Priestly of UC San Diego. “In the early days, they would say (that anything which) increases the strength of the structure can only be good.”

But Priestly said the lesson of the collapse is that the influence of the flares “can be very bad.”

Caltrans officials said they now are re-evaluating the hundreds of bridge columns elsewhere that also were built with flares. Structural engineering professor Frieder Seible of UC San Diego said some flared columns are safe, while others can be made safe with jackets of extra steel reinforcing.

Some of the biggest flared columns in California are being used on expansion of the Harbor Freeway near Downtown. Caltrans engineers said the columns survived the quake with no damage.

But Caltrans has decided to exclude flares when rebuilding the collapsed interchange of the Golden State and Antelope Valley freeways. “There’s something going on here,” said Maroney, the Caltrans bridge engineer. “We need to evaluate it.”

Engineers also are studying other aspects of the bridge’s design, including the angle of the columns.

* Golden State-Antelope Valley freeway interchange: This site 21 miles north of Downtown had partially collapsed during the Sylmar quake while under construction. It is vital to commuters from the Antelope Valley. Among them on the morning of Jan. 17 was motorcycle officer Dean, who plunged to his death from the collapsed ramp linking the westbound Antelope Valley Freeway to the southbound lanes of the Golden State Freeway. The connecting ramp from the Antelope Valley to the northbound Golden State also fell.

Engineers believe the culprits were columns that proved too stiff, along with expansion joints that were too narrow. Again, retrofitting probably would have saved both elevated ramps, officials said.

After the 1971 quake, Caltrans installed devices to strengthen the bridge decks at the interchange. But records show that of all the single-column bridges identified statewide for retrofitting, this interchange was the only one where repairs were not under way.

Records show that retrofitting design work began in 1992. But two obstacles emerged: The range of hard and soft soils at the interchange required extensive analysis. And Caltrans had to decide whether it would be more cost effective to erect a new structure that would be better suited to the soil conditions than to spend $11.7 million for retrofitting.

“It would be imprudent to retrofit if you are going to rebuild everything else in there,” said Roberts of Caltrans. “And I think they were in the process of coming to that conclusion.”

Roberts acknowledged that the site was not ideal for a major interchange. “If you had all of the knowledge of foundation conditions then that you have today, you would try and get out of there,” he said.

Rebuilding the interchange will cost an estimated $34 million.

* Golden State Freeway at Gavin Canyon bridge: Located 23 miles north of Downtown, this 80-foot-high bridge had been placed low on the list of structures to be retrofitted with steel jackets. Top Caltrans engineers cite two reasons for their belief that this bridge was relatively safe:

The structure had survived the powerful 1971 Sylmar earthquake, centered nearby, with virtually no damage. And in 1974, it was outfitted with cable restrainers to keep the bridge decks together at their expansion joints.

Generally, said Gates of Caltrans, “bridges that were successful in 1971 got a good grade” for seismic safety and were placed lower on the retrofitting list.

Roberts had a hand in designing the Gavin Canyon bridge, which was built in 1967, and he inspected it and found it sound after the ’71 Sylmar quake.

Caltrans officials and other experts said this and all other collapsed bridges would have survived if retrofitted. But records show that Gavin Canyon was so low on the retrofitting list that no design work had begun.

It would have cost an estimated $2.2 million to retrofit--and it now will cost $14.8 million to rebuild.

One reason the cluster-column bridge had not been fitted with steel jackets, Roberts said, was that Caltrans had decided that spans supported by single columns were more at risk. The clustered columns were considered more complex and more expensive to retrofit.

Seible of UC San Diego said Caltrans engineers acted prudently in 1974 when they placed the cable restrainers in the Gavin Canyon bridge. But the structure failed largely because the support columns were too brittle and the bridge’s expansion joints still had less than twice the capacity demanded by the Northridge quake, he said.

“Clearly (retrofitting) was not adequate,” Seible said. “Otherwise the structure would not have collapsed.”

* Santa Monica Freeway overpasses at Fairfax Avenue and La Cienega Boulevard: Engineers are confident that if the Northridge earthquake had struck just a few months later, this part of the nation’s most heavily traveled freeway would not now be a demolition site.

Retrofitting of the clustered columns for the two overpasses was to begin this month. Those columns, like so many others, failed. Engineers have found that the clustered columns were too brittle--but would have performed adequately if retrofitted.

The proof is that just a few hundred yards away, a freeway overpass at Cadillac Avenue suffered no visible damage, they said. Those columns had been outfitted with full-length steel jackets.

The failures along the Santa Monica Freeway point out the vulnerability of columns constructed without enough horizontal steel reinforcing bars. For most of the state’s bridges in need of retrofitting, engineers said that 8 to 10 times more horizontal reinforcing steel is needed.

These spiral-like hoops of steel provide strength and flexibility to columns. By retrofitting the columns with steel jackets, engineers can compensate for the inadequate construction.

Otherwise, said Caltrans’ Maroney, “it’s like the difference between what happens if you pour a glass of water onto a table, or into a glass. Without the horizontal steel to contain it, the concrete just explodes outward.”

Retrofitting of the two Santa Monica Freeway overpasses would have cost a total of $4 million, records show. The estimated cost to rebuild the Santa Monica Freeway: $15 million to $21 million.

The two Santa Monica Freeway collapses were precisely the kind of failures that engineers feared when they examined the damage to the Santa Ana-San Gabriel River freeway interchange, which barely withstood the 5.9 Whittier earthquake of October, 1987.

“These two failures are almost identical to what happened to the 605/5 interchange,” said John F. Hall, a Caltech engineering professor who is studying the Northridge quake for the Earthquake Engineering Research Institute.

Why, seven years after the Whittier wake-up call, were these two overpasses not retrofitted?

The overpasses were supported with clustered columns, so they had a lower priority. The design work for the retrofitting started 2 1/2 years ago and construction was to begin this month.

Hayden said the failure to quickly retrofit bridges on the nation’s busiest freeway points out the fallibility of Caltrans’ priorities. “They have the money,” he said. “It’s a question of what they spend it for.”

Setting priorities for repairs remains the challenge for the engineers and politicians entrusted with making bridges and overpasses as safe as possible. But as the Sylmar, Whittier, Loma Prieta and Northridge earthquakes have shown, even the best-informed engineering assumptions can tumble like so many guesses.

As for bus driver Faust, he has won a commendation for his efforts the morning of Jan. 17. He is hoping that the earthquake professionals get it right before the next one. But when he makes his afternoon run these days and comes upon one overpass, “I’m looking up for cracks--and keeping my foot to the floor.”