Dancing Towers on Hamburg's Reeperbahn - Putzmeister

On site On site
The making of a
“Modern Marvel”
[Putzmeister America, October 2009]
The Mike O‘Callaghan-Pat Tillman Memorial
Bridge – better known as the Hoover
Dam Bypass Bridge – is one of the most
ambitious construction projects in the
USA. With a span of m between the
twin concrete arches, once complete, it
will be the longest in North America and
the fifth longest concrete arch bridge in
the world. Its apex reaches a height of
4 m over the Colorado River.
Stationary concrete pumps and placing
booms from Putzmeister mastered the
high demands of concrete pumping in
this Colorado River bridge construction
project.
As was done 76 years ago, the Hoover Dam
is again making its mark in history books.
Crews are conquering an engineering feat of
constructing the most technically challenging
bridge ever to be built in North America,
the Colorado River Bridge. To help place
concrete for this one-of-a-kind project, two
Putzmeister placing booms and BSA trailer
pumps are taking on the obstacles presented
by the Hoover Dam surroundings.
The bridge is part of the Hoover Dam Bypass
project, will hover around 274 m above the
Colorado River and run parallel to the dam.
The bridge, with two lanes in each direction,
is being built in an effort to alleviate traffic
on U.S. Highway 93, which currently crosses
the Hoover Dam to pass over the Colorado
River.
Because the highway is the major commercial
corridor between Arizona, Nevada and
Utah as well as on the North American Free
Trade Agreement (NAFTA) route between
Mexico and Canada, the traffic congestion
(an average of 14,000 vehicles a day) caused
by the existing highway across the dam,
imposes a serious economic burden to the
country.
In addition, the traffic volumes, combined
with the sharp curves of the highway near
the Hoover Dam, create a potentially dangerous
situation for Hoover Dam visitors
and dam facilities. Once the Colorado River
Bridge is complete, no through or truck traffic
will be allowed on the existing roadway;
only Hoover Dam visitors will be permitted.
Choosing the right system
Planned amounts of concrete and steel for bridge construction
Obayashi/PSM JV, a joint venture of Obayashi
Corporation and PSM Construction USA,
Inc., the general contractor, began construction
on the 579 m long open spandrel deck
arch bridge in early 2005.
Obayashi/PSM JV had its work cut out for
them; the project included the pre-casting
and erection of pier columns up to 91 m tall;
construction of the twin, cast-in-place segmental
concrete arch spans; and the installation
of temporary twin cable stays that have
a 762 m span and are 101 m tall to support
the arches during construction.
“We called Putzmeister right away to discuss
the project and what our possible concrete
placing solutions for this complicated project
would be,” says Wes Pollnow, construction
manager of Obayashi/PSM JV. “We
needed to know which solution would make
the most sense and which would be most efficient;
they have a true complete systems
69 N/mm 2 concrete in the arches 6,499 m 3
41 N/mm 2 concrete in the pier columns and caps 6,395 m 3
31 N/mm 2 concrete in the bridge deck 4,193 m 3
28 N/mm 2 concrete in the footings and abutments 5,106 m 3
21 N/mm 2 concrete for column infill 1,575 m 3
Reinforcing steel 3,765 t
Structural steel 3,084 t
Post-tensioning steel (permanent) 384 t
Post-tensioning steel (temporary) 680 t
approach, helping us from the beginning of
the project.
The placing system they chose to maximize
their concrete placement for the arch was
MX 32-4 Multi and MX 36-4 Multi placing
booms and BSA 2107 HP-E and BSA 2109
H-E trailer pumps.”
Overcoming the extreme
To date, Obayashi/PSM JV has pumped and
placed about 10,000 cubic yards (7,646 m 3 )
of concrete for the Colorado River Bridge.
Jeff St. John, project manager of Obayashi/
PSM JV, says the pump manufacturer helped
their team determine how and where to
mount the placing booms and position the
trailer pumps for all portions of the project.
“For construction of the twin arches, we positioned
one trailer pump near the base of
the Nevada arches and one on top of the arch
footing in Arizona,” comments St. John. “A
placing boom was also positioned on each
the Nevada and Arizona side of the twin
arches.”
The separate placing booms and their pedestals
were flown via crane to each of the twin
arches for mounting on their specially-designed
platforms.
As a result of the blazing heat, and to
prevent traffic problems, most of the
concreting was carried out at night.
10 PM 4307 GB PM 4307 GB 11
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