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Collapse of Overpass in California Becomes Lesson in Construction

May 10, 2007 at 6:30 PM EST
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JIM LEHRER: Now, lessons learned from the California freeway collapse in Oakland. NewsHour correspondent Spencer Michels has our Science Unit report.

SPENCER MICHELS, NewsHour Correspondent: At 3:40 a.m., on the last Sunday in April, a gasoline truck crashed into the guard rail on a major California freeway near the San Francisco-Oakland Bay Bridge and burst into flames. The fire was so intense, it caused an overpass to collapse.

The damage closed two heavily traveled freeways and caused commuters to alter their routes. The collapse of the freeways was more than just a local traffic nightmare; it was an object lesson in freeway construction and destruction. And it had many similarities to the obliteration of the World Trade Center.

Abolhassan Astaneh should know. He’s a professor of civil engineering at the University of California at Berkeley and was one of the leading structural engineers who studied the collapse of the World Trade Center on 9/11.

ABOLHASSAN ASTANEH, University of California, Berkeley: In both of them, basically, the fire was the reason why steel got soft and weak and collapsed. In both of them, I feel that we, as engineers, if we had looked at them and learned the lessons, we could really apply these lessons to build safe structures.

SPENCER MICHELS: Astaneh quickly fired off an application to make a forensic investigation of the crash, to figure out why the structures behaved the way they did, and to prevent it from happening again. Within three hours, he got word he was awarded a $25,000 grant from the National Science Foundation, which also partly funds the NewsHour’s Science Unit.

But getting the grant money was only part of the challenge. Astaneh, a native of Iran, had to use his ingenuity to gain access to the collapse site, because the California Department of Transportation, or Caltrans, delayed sending him the necessary paperwork.

ABOLHASSAN ASTANEH: I don’t know exactly why Caltrans did not act as fast as this thing requires. You know, when you get a grant in three hours, you expect to start your project the next hour, not after three days.

Collecting steel remnants

Abolhassan Astaneh
University of California, Berkeley
Those steel pieces are important to the scientific community, you know, to study them and see how much temperature it was.

SPENCER MICHELS: With no time to waste, Astaneh, who has 35 years' experience investigating earthquakes and other disasters, donned a hardhat and a reflective vest. He and his graduate student managed to get into the crash site without formal permission. They took photos of the damage before demolition crews could destroy the data.

ABOLHASSAN ASTANEH: This data is so unique. What you see behind me -- this specimen -- is the most valuable specimen you can have regarding bridges subjected to fire.

SPENCER MICHELS: Using whatever it took, Astaneh confidently gathered information. He made his case to Caltrans engineers who were on site.

ABOLHASSAN ASTANEH: ... because every time there's something like this, you guys at Caltrans, the responsibility you have is to clean it up as fast as you can, to rebuild as fast as you can. That is your job. But at the same time, those steel pieces are important to the scientific community, you know, to study them and see how much temperature it was.

SPENCER MICHELS: He gained an ally by speaking Farsi to the senior resident engineer who turned out to be a fellow Iranian-American. And he persuaded the operator of an elevated work platform to take him right up next to the damaged stub of the freeway, where he could photograph and take samples of the burned steel. He says his trained eye can figure out some details, like temperatures during the fire, on the spot.

ABOLHASSAN ASTANEH: Here, it most likely reached about 1,000 to 1,500 degrees. And that is enough to collapse them, so they collapsed. So the word "melting" should not be used for girders, because there was no melting of girders. I saw melting of girders in World Trade Center.

SPENCER MICHELS: But they got soft, though, didn't they?

ABOLHASSAN ASTANEH: Yes. When steel gets to 1,000 degrees, it loses its strength.

SPENCER MICHELS: Astaneh spent a lot of time attempting to make sure Caltrans didn't recycle the damaged steel, clues to the collapse.

CALTRANS EMPLOYEE: They've been cut; a lot of them have been cut.

CALTRANS EMPLOYEE: Yes, 40 foot. We cut them about in half.

Building freeways further apart

Abolhassan Astaneh
University of California, Berkeley
How do you do it? Very simple, just build your bridge taller, very simple...

SPENCER MICHELS: What he found out was that it had been taken to a large scrap yard so it could be sold. He called it crime-scene evidence and worried it would meet the same fate as the World Trade Center steel.

ABOLHASSAN ASTANEH: After 9/11, we realized that the Port Authority of New York and New Jersey has sent all this steel that we need to study. That's why I'm here to study steel. To send steel to a recycling plant to go to China for recycling, for what? For 15 cents a pound. That's nothing. And all the evidence of steel went to melting pot.

SPENCER MICHELS: After 9/11, a law was passed requiring that such materials be saved for study, but, in this case, it was Astaneh's direct dealing with fellow engineers that preserved the evidence. For Astaneh, this small triumph was tempered by his discovery a few days later, after looking at his photos...

ABOLHASSAN ASTANEH: I found that the location of one of these sampling -- these are called cores -- certainly there's a crack here. You can see this crack here. And that crack, in my opinion, should have been really a call for Caltrans to indicate that, "Now we need to do more investigation, because we don't know how many cracks are where."

I think that the politicians are putting too much pressure on the engineers to get it open. I think this should not be repaired until we are sure that we know what is that (inaudible) what is inside it, what is safe.

SPENCER MICHELS: A Caltrans' spokesman, when told of Astaneh's discovery and his other concerns, declined to respond with an on-camera interview, but in an e-mail, wrote, "Caltrans is already looking at what changes, if any, we should consider in light of this rare occurrence. Caltrans is certainly interested in what others may come up with help us manage all risks."

One change Astaneh thinks Caltrans should seriously consider is building freeways further apart, so that a fire on one level does not destroy the roadway above it.

ABOLHASSAN ASTANEH: How do you do it? Very simple, just build your bridge taller, very simple...

SPENCER MICHELS: So these are too close together?

ABOLHASSAN ASTANEH: Yes, they were actually only 20 feet apart.

Government dismisses dangers

Mary Peters
Secretary of Transportation
Certainly, we can learn from this, but the system is absolutely safe.

SPENCER MICHELS: Astaneh has been lobbying policymakers to draw lessons from this accident. He thinks double-decker freeways at critical junctures should be redesigned, using more fire-resistant steel and paint, which are already in use in Japan, or coating the steel girders with concrete, which can work as a fire retardant.

ABOLHASSAN ASTANEH: Now we are rebuilding just the same way (inaudible) because we want to get this catastrophe out of our way. This is disaster in the Bay Area. Yesterday, I spent two hours on traffic, OK? So what we should do is, let's build this as fast as we can, but we have to identify critical bridges. We have to identify where structures are too close to my bridge, to steel bridges.

SPENCER MICHELS: And do some rebuilding?

ABOLHASSAN ASTANEH: Right.

SPENCER MICHELS: OK.

But at a news conference attended by a number of politicians, who trekked through the mud at the construction site, the U.S. secretary of transportation, Mary Peters, dismissed the threat of danger resulting from freeway design.

MARY PETERS, Secretary of Transportation: We certainly believe that the highway system around the country is safe. We're doing an analysis to determine what happened here. And, certainly, we can learn from this, but the system is absolutely safe.

A quick rebuilding of the overpass

SPENCER MICHELS: Peters said the federal government will pay to repair the damage, starting with $2 million immediately. California's director of transportation, Will Kempton, said the state is going to study its freeway bridges.

WILL KEMPTON, Director, California Department of Transportation: The system is safe. This was a freak accident. But, obviously, we want to do whatever we can to try to avoid these incidents in the future.

SPENCER MICHELS: Engineers working for the state have taken core samples of concrete and steel and already begun analyzing some of the burned parts at labs in Sacramento and in Austin, Texas. It was as a result of this analysis that the lower roadway was reopened, after some quick repairs, just a little more than a week after the accident.

Like the professor, Caltrans officials cut through red tape of their own. They expect to have the roadway opened in record time, and they are paying the quickly hired contractor a $200,000 bonus for each day the job is finished prior to a June 27th deadline.