Bridging the Fox
A historic bridge crossing the
Fox River in a Chicago suburb relied on precast
concrete to preserve its looks during a rehabilitation.
By Leslie Lichtenberg
Stretching 115 miles from
southern Wisconsin through northern Illinois,
the Fox River is a well-known body of water
that serves as a centerpiece of suburban life
in many Midwestern towns. Millions of people
live within a short distance of the “Fox,”
as it is commonly known. A heavily used recreational
area, the Fox is surrounded by bicycle paths
and serves as a popular spot for fishing enthusiasts.
More than 22 bridges span
the Fox River in Kane County, Ill., alone, including
the recently renovated North Avenue Bridge in
Aurora. The North Avenue Bridge stands as a
shining example of the architectural, aesthetic
and historic advantages of using precast concrete.
Originally built in 1926,
the bridge was reconstructed after a study by
the Kane County Division of Transportation recommended
an enhancement of the area’s transportation
network in order to accommodate expansive suburban
development. The 1990 study supported a rehabilitation
and expansion of the bridge, which had not been
maintained since 1974, in order to offset increased
traffic congestion and improve vehicular and
pedestrian access. The $3.8 million project,
which actually comprises two bridges –
one runs from west to east and ends at an island,
and one crosses the river – began in April
2002 and was completed in December of the same
year.
Centering on reconstruction
of the bridge decks, sidewalks, concrete handrails
and lighting, as well as minor repairs to the
arches and piers, the project relied heavily
on the use of precast concrete to help maintain
its historical significance and original appearance.
Working with preservation experts to produce
a bridge reminiscent of its era was the chief
responsibility of designer Bill Epp of Lonco
Engineers in Naperville.
“We tried to re-create
what was there. By using precast concrete, we
were able to design the bridge with a lot of
replication,” said Epp.
Using original drawings obtained
from the county’s historic preservation
agency, the engineers re-created the look of
the initial bridge, beginning with precast beams,
which were installed across the width of the
bridge and separated by decorative spandrels.
Beam lengths ranged from 52 feet to 60 feet,
and the spandrels varied between 4½ feet
and 7 feet tall. Precast panels were then installed,
followed by a prestressed concrete deck, which
helped to accelerate the construction process
significantly and provide a secure surface upon
which cast-in-place columns were poured. The
final elements to be added, including precast
handrails, balustrades and light poles, were
designed as exact replicas of the originals.
A decorative stain was used to coordinate and
match all of the bridge elements.
“The quality of a plant-produced
product was critically important in this job,”
said Stephen Fossler of precast manufacturer
Aurora Concrete Products, North Aurora, Ill.
“Every form was manufactured and inspected
in the lab in accordance with NPCA (National
Precast Concrete Association) standards. The
end result was a beautiful bridge.”
In addition to quality, timing
was also critical for the North Avenue Bridge,
which carries an average of 16,000 vehicles
daily. Closed to cars and pedestrians for eight
months, the 545-foot bridge provides access
for businesses located on both sides of the
river. Although not a major thoroughfare, the
bridge is one of only a few river crossings
in the area. Faced with the challenge of rebuilding
two bridges in one year, the contractors and
engineers selected precast concrete as the method
of choice.
“We did look at other
materials,” said Epp. “We could
have used steel beams, for instance, and achieved
the same look, but because we had to have the
bridges open by December, we knew precast would
speed the construction.”
Geographic restrictions and
weather problems notwithstanding, the project
was in fact completed in less than a year.
“The biggest challenge
was working over the Fox River,” explained
Don Schultz of Herlihy Mid-Continent Co., general
contractors on the project. “We had five
major floods throughout the course of construction.
If we had used poured-in-place concrete, we
never would have gotten the job done,”
he said.
“There’s no question
that quality increases with the use of precast
on a project such as this,” added Epp.
“With the number of beams and columns
involved, it would have been extremely costly
in terms of labor and formwork had we used other
materials. Plus we would have had the added
challenge of having to pour concrete over the
river.”
Historic architecture, a
beautiful river and big-city convenience with
a small-town feel are among the many distinctive
features of Aurora, Ill. Today, Aurora also
boasts a 1926 bridge preserved and renovated
to withstand 21st century living. Located just
south of downtown, the bridge has a new deck
to carry three lanes of traffic, rehabilitated
arch rib supports beneath the roadway and reconstructed
sidewalks for pedestrians. It also allows direct
access to the island and the river for picnics
and other leisure activities. All in all, this
historically significant structure reflects
the aesthetic beauty, quality, efficiency and
cost savings that are possible with the use
of precast concrete.
“This bridge is a perfect
example of what precast can do,” said
Fossler. “Even with a challenging time
frame and cost considerations, we were able
to return the bridge its 1920s look.”
In doing so, these designers
and engineers re-created a modern structure
that responds to the needs of a growing city
while preserving its historic roots.
Project
Profile
Project Name:
North Avenue Bridge
Owner:
City of Aurora, Ill., and Illinois Department
of Transportation
Designer:
Lonco Engineers, Naperville, Ill.
Engineer:
Reynolds, Smith & Hills Inc., Naperville,
Ill.
Contractor:
Herlihy Mid-Continent Co., Romeoville, Ill.
Precast Manufacturer:
Aurora Concrete Products, North Aurora,
Ill. *
* Aurora Concrete
Products is a certified plant under NPCA’s
Quality Assurance/Plant Certification program.
