Project
Specs:
Bridge Type: Railroad Truss
Steel Tonnage: 1,718 Tons
Steel Type: Grade 50
Coating: Painted
The Project Team:
Project Owner: PennDOT
Contractor: Allan A. Myers, Inc.
Designer: Gannett Fleming, Inc.
Detailer: Tensor Engineering
Steel Fabricator: High Steel Structures,
Inc.
Steel Erector: Cornell & Company, Inc.
Description:
The fruits of High Steel's labor are
visible from almost every vantage point in King of Prussia,
PA, thanks to this huge, 1,700-ton railroad truss. The
bridge, which spans I-76, is part of PENNDOT’s $280
Million U.S. Route 202 Improvement Project, which widened
five miles of Route 202 in Montgomery County, Pennsylvania
to six lanes.
Designed by Gannett Fleming, Inc.,
the $8.1 million dollar structure consists of two 240-foot
long, 42-feet high truss sections. High Steel fabricated
and shipped over 800 individual
components
for the structure. Each piece was painted with a three-coat
system, which required over 3500 gallons of inorganic zinc,
epoxy, and polyurethane.
The project specifications required
complex fabrication of mill to bear connections at the top
truss cords. Because of required fit in the field, the bottom
cords were not connected to the top cords during set-up
at High Steel’s yard. Therefore, accurate engineering calculations
and CNC drilling were crucial to avoid project delays.
To minimize traffic disruptions along the busy interstate, general contractor Allan A. Myers,
Inc. and erector Cornell & Company, Inc. chose the balanced cantilever method to erect the bridge. Half of the structure was assembled alongside the westbound lanes on four 330-ton rollers, and the other half was assembled in place alongside the eastbound lanes.
The weekend the truss was moved over
the highway, traffic was reduced to one lane in each direction,
and crews erected a steel support tower and a runway system
in the westbound lanes to roll the truss into place using
two hydraulic winches. The procedure was completed just
after midnight on Sunday, October 6, 2002, and awed Monday
morning commuters were amazed to see the giant structure
where none had been on Friday evening.
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