ABOARD THE RELIANCE, IN SAN FRANCISCO BAY -
Bobbing in a motor boat, it's possible to spy the birth of one of
the largest public-works projects in state history.
Welders fire up torches. Hundreds of workers scale
steel cages. Fourteen King Kong-sized cranes loom over the gray
water.
State transportation officials are overseeing the
construction of a new span of the Bay Bridge, the heavily traveled
link between Oakland and San Francisco.
Their goal: To erect a commuter roadway that can withstand
- or least survive largely intact - a catastrophic earthquake.
That's where the University of California San Diego
comes in.
Structural engineers on campus, working in a university
lab that simulates earthquakes, have tested key design components
of the bridge to ensure it can withstand a major temblor.
The $2.9 billion replacement span is expected to fully
open in 2010.
Frieder Seible, dean of UCSD's Jacobs School of Engineering,
said the 2.2-mile roadway will incorporate structural technology
developed on the La Jolla campus.
"This project is special," he said. "It's
a beautiful engineering challenge, that bridge."
The bridge will replace the double-deck span connecting
Oakland to Yerba Buena Island, in the middle of the bay. The western
segment of the Bay Bridge, linking Yerba Buena to San Francisco,
won't be affected.
The battleship-gray bridge lacks the postcard appeal
of the Golden Gate Bridge and the sweeping elegance of the San Diego-Coronado
Bridge.
But it's a key artery of workaday life in the Bay
Area. About 280,000 cars and trucks cross it daily, compared with
about 94,000 vehicles that traverse the San Diego-Coronado Bridge.
1989 disaster
The east span of the Bay Bridge, however, has been a major concern
to Bay Area residents and state Department of Transportation (Caltrans)
officials since the 1989 Loma Prieta earthquake here.
That 6.9-magnitude quake, which killed 63 people,
caused the collapse of an upper segment of the double-deck structure.
The new bridge will consist of two side-by-side decks,
each providing five lanes of traffic, along with 10-foot-wide shoulders
and a bike and pedestrian path.
Each bridge column will be anchored by 300-foot-deep
piles, running deep below the bay floor. The existing east span
has 70-foot piles.
The structural centerpiece will be a 525-foot-tall
suspension tower, draped with cable. Caltrans officials say they
believe it will add grace to the Bay Area skyline.
Construction on the span started two years ago, but
only recently began to make a mark on the skyline. Bridge columns,
each a complex nest of steel and concrete, are beginning to poke
out of the water.
Each day, hundreds of construction workers are ferried
by boat to the project.
"The work is going well," said Dan McElhinney,
a chief deputy district director with Caltrans. "The scale
of it is really fantastic."
The project is being financed with a combination of
state taxes, bond revenues and toll money collected on state-owned
bridges in the Bay Area.
Mindful of the state budget mess, McElhinney promises
"we're doing everything we can to minimize expenditures on
the project . . . That's a very big concern of ours."
Reason for cost
Caltrans officials say building a project strong enough to weather
a seismic catastrophe can't be done on the cheap. Government scientists
say it's very likely a severe earthquake will strike the region
within the next 30 years.
"The importance of seismic safety has to be weighed
against the overall cost," McElhinney said.
UCSD's Seible said $4.5 million of structure tests
have been conducted on campus. Models of bridge columns and other
components were erected in the university's earthquake testing facility
to gauge their strength.
Additional tests are expected later this year, he
said.
The tests led to some design modifications and additional
seismic safeguards. For example, the Bay Bridge suspension tower
will include steel links designed at UCSD to flex during a quake.
Special hinges will be installed under the elevated
roadway to further absorb seismic shocks.
The roadway itself is being built in segments in Stockton
and will be barged in once the bridge columns are complete.
When the replacement span opens, the old east bridge
will be razed. The Bay Bridge cost $78 million when it opened in
1936, six months before the completion of the Golden Gate Bridge.
George Steil, a lifelong San Franciscan and a construction
foreman on the replacement job, likened the loss of the old double-decker
span to "losing a brother."
Still, he said, the new span will be a major improvement.
"It's going to change the skyline here," he said. "It's
going to be amazing."
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