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Getty Center Tram Guideway
Los Angeles, California
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Getty Center
 The
Getty Center Tram system transports visitors from an underground
parking structure to the J. Paul Getty Museum located on a hilltop.
The Tram vehicle is cable driven and supported by an air cushion.
The total guideway length is 3540 feet (1080 m), with the aerial
portion at 2625 feet (800 m) and an average span length of 210 feet
(64 m). The guideway is single lane, with a double-lane, off-center
bypass section.
The superstructure configuration was chosen by the project’s
owner, architect, and contractor from three alternative cross sections
considered during preliminary design, based on cost, aesthetics,
and constructability factors. The chosen section consists of two
L-shaped precast, prestressed concrete web beams spanning from column
to column with a cast-in-place connecting slab forming a U-beam
section. Web beams were designed to support the simple-span applied
loads. Spans were later post tensioned in the field into four- to
six-span continuous units. A 4-inch (100-mm) thick flying surface
was cast on top of the completed U-beam section. The air-cushioned
vehicle runs on the flying surface.
AutoCAD software was used to develop each precast element in its
spatial geometry and then rotate the piece into its geometry in
the forms. Precast web beam construction permitted casting over
10,000 inserts directly into the concrete to a tolerance of 1/8
inch (3 mm).
At some locations the guideway is supported on columns over 43
feet (13 m) high. At other locations the guideway superstructure
is supported directly on drilled pier caps without columns.
 Precast
concrete crossheads were used to speed site construction of these
heavily reinforced pier elements. Grouted sleeve connections were
used to fasten crossheads to columns. Large steel bar lugs were
used to secure the superstructure to the substructure and to resist
lateral and vertical seismic forces. Precast web beams were erected
within one to two days after crosshead erection and grouting.
The J. Paul Getty Trust built a world-class art facility at this
site and thus demanded the highest quality in design and construction
of the transportation facilities. Concrete was the material of choice
for the Tram Guideway to solve the complex structural design and
close geometric tolerances; to provide a warm, clean, and maintenance-free
structure; and to contribute to the ride quality and passenger comfort
of the Tram. The combined use of precast and cast-in-place, pretensioned
and post-tensioned concrete made construction along the preferred
alignment feasible and cost effective.
Project Credits
Owner: The J. Paul Getty Trust, Santa Monica, CA
Architect: R. Meier & Partners Architects, Los Angeles, CA
Engineer: BERGER/ABAM Engineers, Inc., Federal Way, WA
Contractors:
Project: Dinwiddie Construction Co., Los Angeles, CA
System: Otis Transit Systems, Farmington, CT
Guideway: A.T. Curd Constructors, Inc., Glendale, CA
Precaster: The Niobrara River Company, Rialto, CA |