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September/October
2003
With no elevator yet installed, crews
arrive at dawn to climb 18 stories
up the narrow staircase onto the strut.
From here they look down at the existing
bridges from the climbing form system
atop a tower that is only half built.
They are tying and placing rebar in
preparations for pouring the next
lift.
Bolted to the towers, this climbing
form system is powered by a hydraulic
lift, which jumps the platforms up
after each lift is poured. The forms
look like a gigantic boxes, and hold
80 cubic yards (about 160 tons) of
concrete each.
Once the lifts are poured, the sides
of the form move away from the tower,
and the entire form moves upwards
15 feet. Crews must be very meticulous
when performing work at the top of
the towers because once the form system
advances, there's virtually no way
to access that portion of the tower
again. With a short three day lift
cycle at this stage, these towers
will be completed by March 2004.
Each tower's foundation is supported
by eleven, 230-foot-long, 10-foot-wide
drilled shafts and a 700,000-ton rock
island. Seventeen freighters carried
the rock from Canada, which was unloaded
onto barges and either bottom dumped
directly from the barge or placed
by crane with a clam shell bucket.
Geotechnical engineers were concerned
that the immense weight of the rock
islands would settle, causing the
riverbed to sink, and the adjacent
bridge to lean. Just in case, they
installed a flexible bearing system
between the piers and superstructure
of the adjacent Silas N. Pearman Bridge
to allow for this potential movement.
Just west of the towers, HBG personnel
are busy working on the Charleston
Interchange, with 218 piers and 26,694
feet of roadway. This interchange
will connect into Interstate 26 and
will also access downtown Charleston's
historic Meeting Street.
On Drum Island, construction of all
piers in the Cooper River and Town
Creek is underway, and small crews
are finishing up the stressing. In
addition, construction of concrete
foundations within cofferdams is underway
in the river.
June/July
2003
Approximately 43% of the work has
been completed for this bridge - the
largest project in South Carolina
history. There are currently over
400 craft workers on-site, plus an
additional 100 support personnel.
Substructure elements, including
columns and pier caps, are in place,
and crews have begun work on the superstructure.
Both steel and concrete girder placement
will be occurring over the next few
months.
February/March
2003
The strut at W-15 has been poured
along with the first lifts at both
columns. The stripping of both columns
and the strut form was completed in
February.
Both footings have been poured.
Rebar for tower lifts 4, 5 and 6 are
prefabricated and ready for installation.
The climbing forms are being erected
and three lifts have been poured.
Placing of rock to the islands is
ongoing. Quarry stone (main core)
is complete.
90% of the clearing has been done
for the Mount Pleasant interchange
area. The Coleman detour is underway
and is scheduled for the traffic switch
on March 8 2003.
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