Rebuilding Roebling Bridge
By Christina Fisher
Publication: Constructioneer
Date: Monday,
April 6 2009
In order to easily reach and then remediate the Roebling Steel Plant
in Roebling, NJ, an EPA Superfund site, WRS Infrastructure & Environment,
Inc. called W.J. Castle, P.E. & Associates, P.C. to determine
whether an abandoned steel railroad bridge crossing Crafts Creek
could be converted into a roadway bridge able to support vehicles
up to 110,000 pounds. After performing an in-depth inspection of
the existing bridge, William J. Castle, P.E., company president and
project manager, determined that by employing "green" engineering
techniques a new bridge could, in fact, be reconstructed using bridge
members and components already in place. Hydro-Marine Construction
Company, Inc. was brought in to do the construction.
 Repairing The Bridge's Concrete Substructure
After inspecting the existing bridge, Castle found its concrete substructure
to be in fairly good condition. The exception was a voided area at
the water line where the wingwall and the abutment joined together.
Hydro-Marine prepared to fill the void by cleaning out the old concrete
from the existing area, which measured approximately 4 feet wide
by 8 feet high. Hydro-Marine then anchored flexible fiberglass forms
to the face of the concrete. They then sealed off the bottom of the
form with closed-cell neoprene forced under the form, which encased
the entire void.
After installing epoxy-coated rebar, concrete was pumped in from
the top. The fiberglass forms were left in place to provide additional
protection for the area and prevent erosion in the future.
 Rebuilding The Superstructure
The superstructure
of the original bridge consisted of six steel stringers 37 feet 3
inches long. Castle explains that an in-depth inspection and subsequent
analysis determined that these beams, with refurbishment, could be
used on the new bridge to support the required loads.
"These were old steel beams," says Castle, "so we had to measure
them to determine the size of the beams and the designation (ASTM
A7 steel with a minimum yield strength of 30 KSI). We then analyzed
the beams and found they were sufficient in strength and we could
use them."
Although the steel beams were in overall fair condition, there was
section loss and corrosion in the webs and flanges within the first
6 feet of each end of the beams. Both the steel stringers and the
corroded bearing plates would need rehabilitation and repair prior
to use. Hydro-Marine removed the existing diaphragms and beams, setting
them aside to be prepared for installation.
The beams were thoroughly cleaned and 6-foot-long, 3/8-inch-thick
steel bent plates were attached to each end on both sides to reinforce
the deteriorated portions of the stringers. Also, Hydro-Marine welded
new channel studs at 12-inch increments along the top of each stringer
for a composite deck. Due to the deteriorated condition of the existing
bearing plate and the different spacing of the beams on the redesigned
bridge, a new bearing plate was installed along the length of the
bridge seat and anchored into the concrete with 3/4-inch-diameter
anchor bolts with 6-inch minimum embedment.
The original stringer configuration had been tightly spaced at the
center of the concrete abutments for the railroad track with the
fascia beams measuring approximately 8 feet 6 inches. However, WRS
Infrastructure & Environment required a minimum clearance of
13 feet 6 inches to accommodate their vehicles. Therefore, the stringer
spacing was expanded in the final design to approximately 13 feet
11 inches edge to edge of the fascia beams, which provided a clear
roadway of approximately 14 feet 6 inches.
When the stringers were set in their final position, new diaphragms
and 1-1/2-inch thick deck pans were installed, as well as a 1/4-inch-thick
bent plate running along the top edges of the fascia beams. Steel
guiderail posts were spaced at 6 feet 3 inches and attached to the
beams with a 1/2-inch thick base plate and then to the bridge. All
steel components of the bridge were covered in black shop paint with
the exception of the galvanized guide rail. The 7-inch-thick composite-reinforced
concrete deck was poured in place in less than one day.
Bill Castle points out that the new Roebling Bridge will be a key
component in the cleanup of the site, providing access to an area
that had previously been inaccessible.
No less important is the fact that W.J. Castle's design saved its
client approximately $100,000 by rebuilding a bridge with existing
components.
"The unique feature (of this bridge) was the green engineering. We basically
rebuilt the bridge using most of the materials that were out there.
We didn't have to build or construct a new foundation; we repaired
the existing one. We didn't have to design new beams; we refurbished
the existing ones, and then we poured the concrete deck."
Removal of the existing structure began in November 2008. The deck
was poured the first week in January 2009, and the bridge opened
to traffic on January 23, 2009.
The Castle Group consists of three companies — W.J. Castle & Associates,
Hydro-Marine Construction and Simplified Bridge Systems. On the Roebling
Bridge project were:
William J. Castle, P.E. — president,
W.J. Castle, P.E. & Associates and project manager
Janet L. Castle — president, Hydro-Marine Construction Company,
Inc.
Mark Kremper — project superintendent, Hydro-Marine Construction
Company, Inc.
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