Recent Projects
A Joint Venture led by Coraopolis based
American Bridge Co. was low
bidder for the new self anchored suspension bridge over the eastern part
of San Francisco Bay. The JV of American Bridge and Fluor Enterprises
submitted a price of $1.4 billion. The new East Bay SAS Span Bridge has
a single tower, 160 meters (525') tall, composed of 4 legs strutted
together. The bridge length is 565 meters (1,854'), with a 385 meter
(1,263') main span and a 180 meter (591') side span. The deck is over 60
meters (197') wide. With the exception of the caps for the east and west
piers, this entire contract is comprised of structural steel fabrication
and erection.
Foundations
The three foundations of this project are to be constructed under a
separate contract as described above. However, the caps for the East and
West piers must be constructed under this contract due to their sequence
within the superstructure erection. These caps contain 10,500 Mē of
concrete material, 1,700,000kg (1,870 tons) of reinforcing steel, plus
tie-down rods and post-tension ducts. Tower The 160 meter (525') Steel
tower consists of four legs and four vertical sections. The bottom
sections are approximately 1,500 metric ton and the other sections are
approximately 700 tons each. The total tower weight is 13,500,000 kg
(14,850 tons). AB has developed special procedures to erect this tower,
since no crane exists that can pick a 700 ton piece 525' in the air.
Decks
The deck is composed of twin steel boxes of 28 meters (92') each,
strutted together for an out to out width of over 60 meters. In addition
there is a 5 meter (17') wide bike path that is cantilevered from one of
the 28 meter boxes. The deck panels are of varying lengths, and weigh
between 500 and 2,200t each. These heavy picks will require a special
high capacity, shear-leg floating crane to be designed and built unless
a waiver to the Jones Act can be obtained to allow import of one of the
several that exist worldwide. The deck is constructed and supported on
temporary towers or bents (+/- 12,000 ton of material not including pipe
piling) until the main cable is installed. The total structural steel
weight of the bridge is 30,875,000kg (34,000 tons).
Cables
The new bridge will have one main cable that is 1,400 meters (4,600')
long, and 800 mm (31.5") in diameter. It is continuous from deck anchorage up to tower top back down to deck, underneath the deck and
around a diversion saddle, then back up to tower top then back down to
the other deck anchorage. The cable has a weight of 5,200,000kg (5,720
tons), and the hanger ropes weigh an additional 650,000kg (715 tons).
The cable is made up of 137 prefabricated parallel wire strands (PPWS)
with 127 wires per strand. This process of prefabricating parallel wire
strands was developed in the United States in the 1960's and used on
several suspension bridges. In this process, a strand of wires is
manufactured to its final length, seized in a bundle and carefully
marked to prevent twisting, wound onto specially manufactured reels,
transported to the jobsite, and erected on the bridge using a cableway
and roller system to pull it over the towers. It contrasts with the
air spinning technology of cable erection in which wires are installed on
the bridge 1-4 at a time, and seized into strands in place.
Schedule
Work on the new bridge will begin immediately, but on site work will not
begin until May 2007. Tower construction begins in March 2009
and is
complete in May 2010. Deck construction begins in January 2009 and is
complete in May 2010. Cable work begins in June 2010 and is complete in
November 2011. Final completion of the project is scheduled for February
2013.