STOCKTON -- IN THE HEART of the Central Valley, 50 miles east of Oakland's urban bustle, the Bay Area's $10 billion bridge-building renaissance is in full bloom.
Workers here are producing a record crop -- 452 roadway segments for the Bay Bridge's new eastern span, each standing three stories tall and weighing as much as nine fully loaded Boeing 737 jet airplanes. Even the crane to move them is massive, weighing 500 tons and able to lift 800 tons.
Everything about the new Bay Bridge is on a grand scale, with some of the biggest work taking place off San Francisco Bay.
It's in Stockton, where the roadway segments are being made in 480- to 780-ton pieces. It's along the Bay shore, where 50,000 tons of riprap, 72,000 cubic yards of fill and 34,000 earthquake drains are stabilizing mud for the new bridge's approach. It's on Yerba Buena Island, where one of the tower's foundations has been built and a tricky temporary detour is under construction.
The Bay Area's toll bridges are being seismically strengthened in response to the 1989 Loma Prieta earthquake, which caused part of the upper deck of the Bay Bridge to collapse.
Still, the work is creating a big economic ripple effect.
Half of the $10 billion of work is dedicated to the new Bay Bridge. It's the nation's biggest ongoing bridge project, with a $5.1 billion price tag and an opening date at least eight years away.
The Bay Bridge, one of the nation's busiest toll bridges, is used by commuters across the region. It's a lifeline for California's economy. And building the new bridge is a complex venture that spans suppliers from the East Bay to Europe. It requires coordination, planning and precision -- and a lot of dollars.
All of that is on display at the Stockton precast yard, where 452 wing-shaped concrete structures are being cast, cured and then barged down the Delta to become roadway segments for the new Bay Bridge's 1.3 mile skyway section.
The 50-acre Stockton yard took nine months to prepare. The previously vacant site off Interstate 5 has been turned into a roadway-making factory, involving more than $100 million of work, employing up to 200 people and using massive concrete forms and enormous cranes.
Currently, the Stockton yard has about 140 employees -- 10 from Caltrans and 130 from contractor KFM, a joint venture of Kiewit Pacific, FCI Constructors and Manson Construction. The crew includes carpenters, cement masons, crane operators and laborers. Most live nearby in Lodi, Manteca or Stockton. Some have reverse commutes from the Bay Area. Others have temporarily moved for the job, like senior bridge engineer David Neumann of Fresno, a 14-year Caltrans veteran who is built like a linebacker.
"It's a once-in-a-lifetime project," Neumann said.
Precast segments usually weigh under 80 tons. The Bay Bridge precast segments are the heaviest ever made for a U.S. bridge, with each weighing between 480 and 780 tons.
Precasting allows the bridge to be built faster with less environmental impact on the Bay. The Stockton yard produces a segment every three days.
"It's about speed. We have 452 segments and we have to get it done in about two years," Neumann said. "It's like an automobile manufacturing plant. There are certain stations and everyone knows their job. It's just a finely-tuned machine."
The Stockton yard has an onsite concrete batch plant built by Pacific Cement of San Francisco, which uses aggregate that is railed in from North Carolina and barged down the West Coast from Canada.
"The concrete is unlike any I have ever seen," Neumann said. "It's high, early strength, yet it's very durable."
Conco Pumping and Belting of Concord will pump about 140,000 cubic yards of concrete into the precast segments, Conco's Mike Cusack said. That's about enough to cover 22 football fields, one yard deep.
Each segment includes a deck with two wing-shaped panels. So far, about 200 segments and 400 panels have been cast, with only one panel rejected, Neumann said. Each segment must be within 1/25 of an inch of specifications, even though it is up to three stories tall and wide enough to accommodate five lanes of traffic and two, 10-foot emergency shoulders.
It takes giant equipment to make such big roadway segments. Italian bridge construction firm Deal supplied a straddle carrier crane, two gantry cranes and concrete forms for the four casting beds in an $18 million contract. The parts were shipped through the Panama Canal, a journey that was delayed by nearly a month because of the 2002 West Coast port lockout.
The gantry cranes, which can each lift up to 165 tons, move panels and steel reinforcing bars.
The $3 million straddler carrier, the world's largest, moves precast segments.
"It's a big beam on wheels," Neumann said.
Big wheels. Sixteen of them, made by Michelin. Each wheel weighs more than 3 tons, has an 11-foot diameter and costs $20,000.
The straddle carrier is computerized and can be monitored via Webcast in Italy. The crane takes two to three hours to move a segment. It goes 2 mph, just twice as fast as a 3,000-ton crawler transporter can carry a NASA rocket to the launch pad.
"It's slow," said Tim DeRosier, a seasoned crane operator with a beard straight out of ZZ Top. "You can feel it. It moans and groans."
DeRosier operates the straddle carrier with his longtime friend and fellow Lodi resident Dennis Dorton. They work a 7 a.m.-to-3:30 p.m. shift.
"We're kind of the unsung heroes out here," DeRosier said.
Dorton, a 24-year operator, helped build SBC Park in San Francisco. "It took me three hours to get home," Dorton said. Now his commute is only 15 minutes.
The straddle carrier moves the roadway segments from the casting bed to a storage area called the "boneyard," where the pieces cure for one to 18 months. The segments are lined up as they will appear on the skyway -- in groups of nine.
After curing, the segments are sandblasted and cleaned. Then the straddle carrier takes them to the dock to be barged to the bridge.
The barge slip was designed by Foster Piling, which has a Hayward office, and PND consulting engineers of Alaska. The open cell system also has been used in the offshore oil industry and heavy dock loads, supporting up to 6,000 tons.
The Stockton open cell slip is more durable, costs less and uses less material than a conventional design, Foster Piling manager Phil Wright said. About 800 tons of sheet pile, made by TXI Chaparral Steel of Dallas, were used in the slip, which can support more than 1,300 tons.
Once the segments are loaded in Stockton, the barge ride takes 10 to 12 hours to Oakland.
Neumann expects that the last roadway segment will be cast in spring 2006 and it will take another six months to wind down operations in Stockton.
"I don't think we'll ever design another bridge like this one," he said.
Alec Rosenberg can be reached at (510) 208-6445 or [email protected]. |
