Matakuliah
Tahun
Versi
: S0182/Studi Kasus Dalam Teknik Sipil
: Juli 2005
: 01/01
Pertemuan 13
Evaluasi Kasus
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Learning Outcomes
Mahasiswa mampu mengevaluasi dan
membandingkan kasus-kasus yang
mungkin terjadi di lapangan berdasarkan
berbagai contoh kasus dan penyelesaian
yang dipelajari , yang akan digunakan
sebagai bahan pertimbangan bagi
pengambilan keputusan di lapangan
nantinya  C6
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Outline Materi
• Tijauan terhadap kasus kegagalan
konstruksi
• Resiko dan dampak yang ditimbulkan
• Meminimalkan resiko
• Pertimbangan teknis dalam
masalah/desain konstruksi
• Pengambilan keputusan
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TACOMA NARROW BRIDGE
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TACOMA NARROW BRIDGE
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TACOMA NARROW BRIDGE
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TACOMA NARROW BRIDGE
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TACOMA NARROW BRIDGE
Activity A: New Bridge Temporary Works
Superstructure crews will continue to
construct temporary works in support of cable
spinning. Scheduled work begins at 6 a.m.
and ends at 10 p.m. An occasional graveyard
shift may occur from 10 p.m. to 6 a.m.
Equipment used may include tower cranes
and winches. August 1-31
Activity B: Tacoma Mainline
Crews will shift concrete barrier and modify
striping for both eastbound and westbound
lanes in order to accommodate both
directions of traffic on the westbound
alignment. This will allow construction
activities to occur on the current eastbound
lanes. The work will take place between 7
p.m. and 7 a.m. Equipment to be used will
include excavators, rollers and dump trucks.
August 8-10
This work is weather dependent and could
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be delayed due to bad weather.
TACOMA NARROW BRIDGE
Connecting Land to Sea: Spinning the Cables
Building a suspension bridge across the Narrows is the
human equivalent of a spider weaving a web across the
space between two trees. It looks fairly impossible. Cable
spinning - laying strand after strand of steel wire - from
the Tacoma anchorage to the Gig Harbor anchorage will
become a simple mechanical process once an aerial is
built.
In late July, the bridge builders reached a new milestone
when workers stretched a steel cable from the west shore
of the Narrows to the top of the Gig Harbor tower. Pulling
the 5/8-inch 'pilot line' is the first phase of installing the
suspension system. In the months ahead, suspension
crews will spin mile after mile of steel wire until a pair of
20½-inch main cables have been spun.
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TACOMA NARROW BRIDGE
Crews pulled the pilot line on a brilliant July morning as eager
engineers and curious reporters waited patiently on the beach.
Directly overhead, two workers pulled the first cable from a
winch at the Gig Harbor anchorage, down a steep bluff and onto
the beach. Once on the shores of the Narrows, the workers
handed the cable off to a crew in a small boat. At the same time
that two men dragged the cable from anchorage to beach,
another team standing atop the Gig Harbor tower, 510 feet above
water level, used a winch to lower one end of a second cable to
deckhands on a Foss tugboat.
Each cable was then pulled toward the other by the work boat
and tugboat. The two boats met under the west span of the
Narrows where deckhands connected the cable ends to a steel
plate. The two winches then raised the connected cables into
place. The whole process - dragging the cable to the beach,
lowering the other cable from the tower and connecting the two took slightly more than an hour.
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TACOMA NARROW BRIDGE
Now that the first wire has been
placed, progressively stronger
wires are being pulled across.
Once the suspended walkway is
complete, steel wires will be pulled
across the Narrows in groups of
four until all 8,816 individual
cables have been placed. But
before the actual 'spinning'
process begins in mid-September,
crews will spend the remainder of
the summer building the aerial
walkways.
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TACOMA NARROW BRIDGE
Concrete is poured into the towers with a bucket that can
handle four cubic yards of concrete at one time. From a
pumping station on land, concrete is delivered through a
pipeline to the pier top, and then placed inside the tapered
bucket. A tower crane, then, hoists the bucket to the top of the
structure and empties the load inside the form.
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TACOMA NARROW BRIDGE
See the animation of TACOMA BRIGDE
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