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Flood damage to California bridges worse than suspected
LOS
ANGELES (AP) — The damage to interstate highway bridges from flash
flooding in Southern California's desert over the weekend proved more
widespread than initially thought, with construction crews working
Tuesday to reinforce spans over three gullies.
Flood damage to California bridges worse than suspected
By JUSTIN PRITCHARD
38 minutes ago
LOS ANGELES (AP) — The
damage to interstate highway bridges from flash flooding in Southern
California's desert over the weekend proved more widespread than
initially thought, with construction crews working Tuesday to reinforce
spans over three gullies.
In light of
the damage, some outside engineers warned that the California Department
of Transportation may need to adopt tougher design and protection
standards for highway bridges, particularly with abnormally heavy rains
possible in the coming months because of the ocean-warming phenomenon
known as El Nino.
Flooding touched off by unusually intense
rainfall of nearly 7 inches Sunday washed away boulders and soil under
an elevated portion of Interstate 10 near the town of Desert Center,
about 50 miles from the Arizona state line, causing the collapse of the
eastbound side of the bridge and severely weakening the westbound side.One person was hospitalized with broken ribs, a shattered knee and lacerations to his liver, and the main highway between Los Angeles and Phoenix was severed, forcing 54,000 daily vehicles to take a several-hours detour.
After the collapse, Caltrans inspectors found erosion under two other I-10 bridges a few miles to the west, and workers labored to reinforce all three spans by pouring more concrete and replacing the protective boulders that were swept away, said Mike Beauchamp, a Caltrans deputy district director.
Authorities hope to reopen the westbound lanes around the collapse site to two-way traffic within weeks. Reconstruction of the fallen eastbound span will take longer.
Caltrans said it inspected 10 bridges over I-10 on Monday and expected to complete the remaining 34 on Tuesday.
The bridge that washed out was built in 1967 and easily passed a March safety inspection. It had been "armored" with boulders lining the gully that runs under the span. The gully is normally dry but can flood during the sudden and intense rainstorms that happen in the desert.
Caltrans said the span would have withstood the flooding if the water had barreled down the middle of the natural channel, but its path shifted, as can happen in the desert, concentrating its full force on the western bank. The soil in that area cannot absorb that much water quickly.
Armin W. Stuedlein, an engineering professor at Oregon State University who studies how structures such as bridges interact with soil, said that in the wake of the collapse, there may be "room for improvement" in bridge design and protection standards.
Caltrans had no immediate comment.
Stuedlein noted that this stretch of I-10 has several dozen similar bridges."Any one of those gullies on any given storm event could be the bad actor," he said.
Another
engineer said he worries that the kind of flooding seen Sunday could
increase in coming months because of El Nino. The periodic warming of
the Pacific Ocean waters could bring heavier-than-normal rains to
drought-stricken California.
"As
the prospects for El Nino continue to grow, what happened a couple of
days ago is probably going to recur," said Ziyad Duron, an engineering
professor at Harvey Mudd College.
end quote from:
http://finance.yahoo.com/news/california-interstate-collapse-reverberates-2-states-074716384--finance.html#
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