33
JUNE 2014
ACT
BRIDGES
INDUSTRY FOCUS
I
n the early1930s, the crews that
built theBayBridge that linkedSan
Francisco toOaklandprobablydid
not considerhowdifficult itwouldbe to
dismantle thehistoric crossing77years
later. In fact, the joint venture company
taskedwithdemolishing thebridge
workedalmost ayear engineering the
demolition, determininghow todismantle
thebridgepiecebypiece, and taking
intoaccount all sortsofmajor league
environmental and safety issues.
The contract for theprojectwas awarded
in January2013 toa joint ventureof
SilveradoContractors andCalifornia
EngineeringContractors. The first nine
monthsof theprojectwere consumed
with engineeringandplanning, including
detaileddrawings andanimationsof every
stepof thedemolition.Crews started
workat thebridge site inSeptember 2013,
D.Ann Shiffler
reports
that dismantling the
old Bay Bridge is a
painstaking process.
shortlyafter thenewBayBridgeopened
to traffic.
For the first sixmonthswork centeredon
removing thebridgedeckandpreparing
the structure forprecisely engineered
demolition so thatwhenapiece is taken
off the rest of thebridge stays intact.
Support beamswere added in strategic
places toassure thebridgedoesn’t collapse
upon itself.
SanFrancisco-basedSheedyDrayage
has supplied fourmobile cranes for the
project that is scheduled tobe totally
completedby July2016. The cranes
include two200-tonLiebherrLTM1160/2
all terrain cranes and two90-tonLink-Belt
HTC8690 truck cranes.
“Generally, one crane isholding the steel
piece that isbeing cut free,while theother
crane ishoisting themanbasketwithmen
whoareburning thepieces loose,” said
Michael Battaini, co-president, Sheedy
Drayage. “Eachpiece that comesdown
is in the exact predetermined sequence
and it hasbeenprecisely engineered
forweight, dimension, and centersof
gravity. Our cranes lower thebeamsonto
awaiting truckon thebridge adjacent to
our cranes.”
Eachpickhasbeen examinedonan
individual basiswith3-Dmodelingused
toanalyzeweights and centersof gravity.
One connectionmembermayneed tobe
cut into10pieces tobemanageable for the
cranebeingused.
“The cranes areworking from thedeck
of thebridge that isbeingdismantled,”
saidBattaini. “Lookingat thepictures,
it’s amazing. Thebridge isbroken in two
nowand the cranes areworking theirway
backwards. The cranes sit right backon
the edgeof that gapandare cantilevered
out. The last point of support is a few
hundredyardsback.”
The cranes are sittingon the lowerdeck
of thedoubledeckbridge. From the lower
deck to the topof the truss varies from
94 feet up to200 feet above the lower
deckand it’s anadditional 200 feet below
to thewater.
Tower cranes to come
Inayearor so, tower craneswill be
installed toassist on theworkneeded to
bedone at higher elevations, according
toRichRiggs, projectmanager,
p
Piece by piece
The average steel beamweighs from
15,000 to 40,000 pounds.
The cranes are sitting on the lower deck of
the double deck bridge. From the lower deck
to the top of the truss varies from 94 feet up
to 200 feet above the lower deck and it’s an
additional 200 feet below to thewater.
PHOTOS COURTESY OF CALTRANS/SAM BURBANK
