(For more photos click on the photo above.)
By Jordan Lebovich, JBL Photography
With perfect
weather and an eager group we set off to tour the new bay bridge that will link
Oakland with Yerba Buena Island. To
start the tour we were shown a short video about the bridge and the progress to
date. The numbers that were covered are
colossal. From the tons of steel, rebar
and concrete to the miles of cable to the dozens of companies and countries
that are involved, it’s hard to comprehend the effort that has gone into the
design and building of this bridge.
The eastern span replacement of the bridge
has been under construction since 2002 and is scheduled to open by Labor Day
Weekend in 2013 at a cost of $6.3 billion. The replacement span is engineered
to withstand the largest earthquake expected over a 1500 year period and is
expected to last at least 150 years with proper maintenance. The Self-Anchored
Suspension (SAS) tower was completed in 2011 and all 28 deck segments on the
span are in place.
Workers have
completed the challenging task of pulling and installing the last of the 137
strands of the nearly 1-mile-long main SAS cable. Each strand consists of more
than 17,000 individual high-strength steel wires. The SAS’s single, nearly
1-mile-long cable is anchored into the east end of the roadway, traveling up
and over the single tower to wrap around the west end before traveling back up
and over the tower to anchor back into the east end; in other words, the
2.6-foot-diameter cable acts like a giant, unbelievably strong sling. The
cable’s diameter is the largest for a self-anchored suspension span and at
nearly a mile-long, the cable is also the longest looped suspension cable in
any bridge. The cable features 118 miles of 2 1/2-inch steel strands and more
than 17,000 5mm wires, each of which can support the weight of a military grade
Hummer. The cable weighs 5,291 tons or nearly 10.6 million pounds. Anchoring
the main cable in the deck itself puts the span into compression and enables it
to remain standing.
The new East
Span of the Bay Bridge features a unique single tower suspension bridge,
connecting to a mile-long elevated viaduct, or Skyway. The parallel roadways of
the new span will provide motorists with sweeping views of San Francisco Bay.
Each deck will accommodate five lanes of traffic and include 10-foot-wide
shoulders to help keep traffic moving. The Skyway has massive pilings reaching
deep into bay and seismic safety devices that will enable the road decks to
move rather than buckle in the event of an earthquake. The Skyway’s decks are
comprised of 452 precast concrete segments, fabricated in Stockton and
transported by barge to the project site. These are the largest segments of
their kind ever cast. They are lifted into place by winches, which were
custom-made for this project.
These are
just some of the features of the new bridge, but there were other
considerations like the wildlife habitat that the bridge spans. The Bay Bridge and other Toll Bridge projects are
global leaders in developing ways to reduce underwater noise caused
by construction activity. In addition,
since birds have been roosting on the original Bay Bridge for years, the
team designed special platforms (a.k.a., “Cormorant Condos”) under the
Skyway to provide nesting habitat in the same area. The project will
provide opportunities for the creation and/or enhancement
of shorebird roosting habitat in the East Bay. The team regularly monitors
birds in the area, such as the Peregrine Falcon, Least Tern, California Brown
Pelican, Double-crested Cormorant and Western Gull, to ensure they
are not disturbed by construction activities.
For more information about the bridge project go to http://baybridgeinfo.org/
