2 L.A. Bridges to Be Strengthened : Repairs: Two Orange County spans are among those considered especially vulnerable if an earthquake strikes the Southland.

Two days after the Bay Area earthquake collapsed part of an Oakland freeway, two Los Angeles County bridges were chosen as the initial targets of a long-delayed seismic repair program to correct a structural vulnerability first exposed 18 years ago.

The bridges, at the junction of the 57 and 60 freeways in the City of Industry and at the intersection of the 405 and 710 freeways in Long Beach, are among more than 700 bridges, many of them in the Los Angeles area, singled out two years ago as having weaknesses that could lead to a collapse in a major earthquake.

The vulnerable bridges are structures supported by single columns, unlike the section of the Nimitz Freeway in Oakland that fell, which was a multiple-column structure. According to state transportation officials, the durability of single-column bridges has been a cause for concern since the 1971 Sylmar earthquake. But transportation officials said that, until recently, Caltrans had devoted its resources to correcting another design flaw regarded as more serious and more widespread.

Ironically, the elevated section of the Nimitz Freeway that crashed Tuesday was one of the structures Caltrans had attempted to strengthen.

In the aftermath of the Nimitz disaster, state officials are seeking to find out more about the California Department of Transportation’s timetable and its priorities for repairing all types of seismically suspect bridges and overpasses.

Assemblyman Richard Katz, a Sylmar Democrat who chairs the Transportation Committee, said Friday that he plans to hold hearings to ask why it has taken Caltrans 18 years to complete only one phase of a multi-part program to reinforce vulnerable bridges and overpasses.

Katz said he is angry that bridges identified as vulnerable two years ago were not targeted for repairs until this week.

“I am frankly very shocked and surprised. If Caltrans said it was that major a problem, why was it sat on?” Katz said.

Caltrans spokesman Jim Drago said there was no connection between the Bay Area quake and the decision to strengthen the structures. He said Caltrans authorized the work a month ago, pending approval by the State Transportation Commission at its regularly scheduled meeting Thursday.

A source within Caltrans who spoke on condition that he not be identified blamed the delay in starting the work on a shortage of funds for highway repair projects.

Transportation officials say freeway single support columns emerged as a potential problem after the 1971 earthquake. However, Caltrans did not begin asking for money to reinforce the columns until after the 1987 Whittier earthquake damaged the 605 Freeway overpass at Interstate 5.

According to the May, 1988, Caltrans analysis, Orange County would have two bridges among the 200 worst single-support freeway structures in the state. Both would suffer substantial damage in an earthquake the magnitude of the temblor that ripped through the San Francisco Bay Area this week, the analysis shows.

One is the eastbound connector from the San Diego Freeway to the Garden Grove Freeway, an expanse of concrete that leads from the right lane and rises high into the air about 2.1 miles from the Newport-Inglewood fault. This bridge was listed as the 101st worst in the state and would sustain damage over more than 400 feet of its length in the event of a major quake.

The second is the overpass separating the San Diego Freeway from the San Gabriel River Freeway. That bridge--about 2.5 miles from the Newport-Inglewood fault--was listed as the 134th worst bridge and would sustain damage extending along about 350 feet of its length in a major quake.

Far more fragile, according to the Caltrans analysis, is the San Diego Freeway bridge over the San Gabriel River, which is in Long Beach but used by thousands of Orange County commuters each day.

The single-support bridge, about 2.6 miles from the Newport-Inglewood fault, is ranked as the eighth most likely bridge to fall in a major earthquake. In a 7.0 quake, nearly 1,800 feet of the bridge would either collapse or be damaged, the analysis said.

A 1987 Caltrans memorandum discussed potential damage and loss of life that could occur to highway interchanges with single columns. It pinpointed 12 interchanges along the Newport-Inglewood Fault and said that a repeat of the earthquake that occurred there in 1933 could lead to the deaths of 100 people as a result of collapsing freeway ramps.

Moreover, the memo said the scenario could be repeated during major earthquakes along the Raymond Hill Fault near Pasadena, the San Jacinto Fault near San Bernardino and the Hayward Fault in the East San Francisco Bay area.

Another memorandum, to the department’s director, Leo J. Trombatore, who has since retired, estimated that it would cost $65 million to reinforce 767 bridges and went on to say that “because of the near failure of the Route 605 structure it is prudent for the Department of Transportation to accelerate (the) retrofit program to prevent collapse of major structures during an earthquake. Contracts can be advertised as early as July 1, 1988.”

The memorandum also said that “the highest priority structures in the Los Angeles area will be started in the first year.”

Several Los Angeles area bridges are now slated for repair. According to Caltrans, they include the San Gabriel River Bridge on the 405 Freeway in Long Beach; the 405 Freeway at Vermont Avenue; the 210 Freeway at Broadland Avenue, Santa Anita, the Santa Fe Dam and Michillinda Avenue; the east and west connectors to the 210 Freeway interchange with the 605 Freeway in Irwindale; the intersection of the Harbor Freeway, Interstate 5 and the Long Beach Freeway; the Long Beach Freeway at the Los Angeles River Bridge; four different bridges on Interstate 5 between the Glendale Freeway and Los Feliz Boulevard; Interstate 10 at Evergreen and Marguerita avenues, and four locations along the 134 Freeway--Columbus Avenue, the Los Angeles River, Doran Street and Orange Grove.

The seismic work to be done represents the second phase of a three-step effort to correct design problems exposed by the Sylmar earthquake and subsequent temblors. Phase One involved using steel cables to tie down elevated freeway decks that cars drive on. That work, ordered for 1,262 bridges and overpasses and costing $54.2 million, was 99% completed by 1987, according to Caltrans documents. Under this program, work reportedly was done on the Nimitz in 1977.

Phase two of the seismic work, approved Thursday, calls for reinforcing highway support columns by wrapping them with flexible steel bars. Phase two will deal exclusively with single-column structures, while phase three, which is still under study, is supposed to focus on multiple-column bridges.

Caltrans’ official position is that the method of reinforcing single-column bridges won’t work on other types. Caltrans officials say the technology for strengthening multiple-column structures like the Nimitz has yet to be developed.

However, a number of structural engineers who specialize in seismic work and one Caltrans engineer have argued since Tuesday’s earthquake that the technology is available to reinforce multiple-column freeways.

Virginia Ellis reported from Sacramento and Frank Clifford from Los Angeles. Staff writer Ralph Frammolino also contributed to this story from Sacramento.

BRIDGES IN NEED OF STRENGTHENING

These Los Angeles-area bridges are among those described by Caltrans as most in need of further strengthening to make them more earthquake-safe: 1. Interchange connecting Santa Monica and San Diego freeways in West Los Angeles. 2. San Diego Freeway bridge over the San Gabriel River at the Orange County-L.A. County line. 3. Interchange connecting Ventura Freeway and Glendale Freeway in Eagle Rock area. 4. Bridge on I-5 in Griffith Park area. 5. Santa Monica Freeway overcrossing above La Cienega and Venice boulevards in Mid-City area of Los Angeles. 6. Long Beach Freeway bridge over the Los Angeles River in South Gate. 7. I-5 bridge over Riverside Drive in the Elysian Park area. 8. Bridges carrying Glendale Freeway over I-5 in the Silver Lake area. 9. Interchange between Pasadena Freeway and I-5 near Los Angeles River. 10. Bridges carrying Hollywood Freeway over Clinton Street in Hollywood area. 11. Ramps from Colorado Boulevard to the Ventura Freeway at the Arroyo Seco overpass area in Pasadena.