Santa Monica Freeway Bridges to Be Re-Examined : Roads: Caltrans will see if any need reinforcement. Goal is to prevent quake damage that could close route.

Dozens of bridges on the Santa Monica Freeway, which reopened this week, will be studied to determine whether they can withstand a major quake without damage that would put them out of service, Caltrans officials said Tuesday.

Because of the importance of the freeway, Caltrans officials said they want to see how many of its bridges needed additional reinforcement to prevent the type of earthquake damage that could force closure of the freeway route.

They said they did not believe that any of the bridges would collapse in an earthquake.

Questions about the level of reinforcement in the Santa Monica bridges were raised during an engineering review of designs for the bridges constructed at La Cienega Boulevard and Fairfax Avenue to replace structures that collapsed in the Jan. 17 earthquake.

Chief Bridge Engineer James E. Roberts said he has not determined how many of the bridges along the Santa Monica will be reviewed but that the examination probably will focus on those that carry freeway traffic and not over-crossings and under-crossings.

At the time of the quake, Caltrans was planning to retrofit about 65 of the 283 bridges on Interstate 10 in Los Angeles County, including the two that collapsed.

Officials said they will reevaluate the retrofitting plans for these bridges to determine whether they need to be upgraded. They also are expected to study some of the bridges retrofitted after the 1989 Loma Prieta earthquake and others for which there were no plans for retrofitting.

The decision to re-evaluate the bridges came after a panel of seismic experts said it had concerns about the seismic rating given the two replacement structures.

Caltrans, working with local officials, had decided not to rate the two new bridges as “important,” a designation that requires extra reinforcement.

Bridges rated as “important” are designed so they can ride out an earthquake without any damage that would cause them to be closed. A bridge that does not have that rating can sustain earthquake damage requiring temporary closure.

Caltrans spokesman Jim Drago said the “important” rating was created at the request of a board of inquiry impaneled after the Loma Prieta earthquake to examine the agency’s seismic retrofitting program for bridges.

The panel proposed that the highest level of reinforcement should be reserved for those bridges that carry emergency traffic or for which there was no alternative route if they were closed.

“How much can you tolerate having a particular structure or route out of service? That’s really what gets to the crux of what we call the importance factor,” Drago said. “Obviously there are certain structures like the Bay Bridge in San Francisco that you can’t afford to go out of service because they’re not easily detoured.”

Drago said he did not know how many bridges on the Santa Monica carry the “important” rating. The Times reported Monday that the two newly constructed bridges were not given that designation.

The reason, Drago said, is that traffic on these two bridges is easily detoured to side streets and back onto the freeway.

But the panel of engineering experts asked the agency to reconsider the designation, noting that a freeway that carries 341,000 vehicles a day should not be subject to closure. Bolstering the recommendation was an economic study by Gov. Pete Wilson’s office showing that the closure of the two collapsed bridges had cost the Los Angeles-area economy $1 million a day.

Roberts said Caltrans agreed with the recommendation and said he would not only change the designation for the new bridges but also would conduct a review to determine if any other major bridges on the freeway had not been retrofitted or designed to meet the “important” standard.

“I think we have to go back and re-look at structures on that freeway and decide that they are ‘important,’ ” he said.

For the newly opened bridges, the change in the designation has meant that Caltrans will have to go back in the next few weeks and strengthen them at the abutments--the concrete sections connecting the bridges to the land--to prevent damage in a major earthquake. Officials say that the work, estimated to cost less than $300,000, would not require closure of the freeway but would involve noisy pile driving.

The panel of experts has said that seismic weaknesses in the abutments could permit earthquake damage that would put them temporarily out of service. Caltrans said the problem can be remedied with installation of eight pilings four feet in diameter that will be tied to the abutments.

Roberts said if other major bridges on the Santa Monica are found to have similar weaknesses, they will probably be reinforced.

Assembly Transportation Committee Chairman Richard Katz (D-Sylmar), a frequent critic of Caltrans, praised the decision, saying he could never understand why bridges on the world’s busiest freeway had not been given the highest seismic rating.

“If the Santa Monica is as critical as the governor says it is, and I believe it is, how can you have some bridges built to no-collapse and no-damage standards and not others?” he asked. “It seems to me the whole freeway needs to be built to the same standard.”

Katz said the freeway would be the subject a special hearing of his committee that he expects to call to examine the procedures Caltrans used in rebuilding the two bridges. Of prime concern, he said, will be the $14.5-million bonus paid to the contractor for completing his work 74 days early.

“We welcome the hearing,” Drago said. “We believe the process we utilized can withstand the tightest scrutiny. We’ve reopened the busiest freeway in the U.S. in record time and it’s a safe structure.”