Engineers Study Oakland, Calif., Overpass Collapse For Ideas For Building A Better Highway
Friday, May 4th 2007, 2:45 pm
By: News On 6
OAKLAND, Calif. (AP) _ Engineers are analyzing bent steel and broken concrete from this week's fiery highway collapse in hopes of learning someday how to build a better highway, capable of withstanding flames that can twist girders like taffy.
What they discover probably won't be reflected in the rebuilt overpass, because there is pressure to replace the heavily traveled exchange quickly, and because authorities see no point in fortifying it against such a rare occurrence.
But ultimately, scientists hope to apply the lessons of the disaster.
``This is the most valuable thing that can come out of this tragic collapse,'' said Abolhassan Astaneh-Asl, a professor of civil engineering at the University of California, Berkeley. He is leading a team of scientists studying the accident with a $25,000 grant from the National Science Foundation.
The freeway collapsed last weekend after a gasoline tanker crashed and caught fire, creating temperatures so intense that the steel supports holding up the overpass above the wreck softened.
Astaneh-Asl said he thinks the fire might not have done so much damage if the distance between the two decks had been greater.
He said a smart course would be to identify critical double-deck arteries, such as the Bay Bridge between Oakland and San Francisco, and see whether measures such as fire-resistant paint or concrete jacketing could be installed.
An expert on how steel and composite structures withstand extreme events, Astaneh-Asl studied bridges and overpasses after the San Francisco Bay area quake of 1989, which collapsed a double-deck highway. He also studied the World Trade Center disaster.
The repair project is on a fast track. Gov. Arnold Schwarzenegger said the lower section _ connecting westbound Interstate 80 with southbound Interstate 880 _ could be back in service as early as next week.
Rebuilding the upper section, Interstate 580 connecting San Francisco to its eastern suburbs, will take considerably longer, but the California Transportation Department set a target date of June 29.
Mark DeSio, deputy director of external affairs for Caltrans, said it would be pointless to redesign the overpass against another such accident.
``This was an extraordinary, rare event,'' he said. ``Such an occurrence is enormously more unlikely than the earthquakes and floods that California's bridges are currently being designed to resist.''