CONSTRUCTING
SUBURBIA
THE HIDDEN ROLE OF PRESTRESSED CONCRETE
Robert M. Frame III
and Richard E. Mitchell
M
oving into their
new ranch-​style
houses in post-​World
War II suburbia,
young families needed more than residences. A new suburban infrastructure accompanied the better-​known
housing boom of the era. Educational,
social, and religious needs required
schools, community centers, and
places of worship. For commerce, developers conceived shopping centers
and the supermarket. Spacious industrial parks accommodated the expansive, low-​rise office buildings and
industrial plants where many would
158 M I N N E S OTA H I S TO RY
work. Automobiles, the common
denominator of suburban transportation, would ride on new roads, as the
federal government funded a massive
national interstate highway system.
To meet demand while keeping
costs down, architects, engineers,
and contractors stressed speed, economy, and efficient construction over
complex, unique architectural styles.
Speed meant mass production of
standardized building components
for quick on-​site assembly. Similar
criteria governed highway construction. The new limited-​access freeways crossed over and under many
existing roads instead of intersecting
them. Multiple crossings meant that
many new, identical bridges had to
be built quickly and economically.
Ornate design was out and economy
was in.
Contractors quickly adapted a new
technology for concrete, prestressing it to create the simple modular
panels, planks, and beams needed for
long-​span floors, roofs, and bridges.
Under controlled factory conditions,
plants mass-​produced these modular
components to standardized specifications. Seemingly overnight, buildings
and structures of all kinds—​including
motels, shopping centers, sports
stadiums, and high schools—​began
incorporating prestressed-​concrete
products. And Minnesota firms
began producing structures ranging
from a small prestressed-​concrete
picnic shelter to major parking
ramps and the elevated roadways at
Minneapolis—St. Paul International
Airport. Often visible yet unrecognized, prestressed concrete became a
key structural material in buildings of
all types.
C
oncrete components generally come in three forms: plain,
reinforced, and prestressed. Although
widely used since the late 1890s, reinforced concrete’s special properties
limit its application. Like stone, concrete is very strong in compression—​
facing: Installing prestressed decking on an
elevated roadway at the new Minneapolis—
​St. Paul International Airport, about 1960
(Northwest Architect, Jan.–Feb. 1961, facing
page 74). The challenge—​successfully met,
as the 1990s photo (above) shows—​was to
support maximum “live loads” with minimum
construction depth.
when a force or load pushes directly
on it, as on a vertical column. Placed
horizontally, as a beam, it tends to
crack with tension along the bottom
edge unless it is reinforced with
metal. The longer the distance a beam
spans, the larger or deeper it must be
to reduce cracking or breaking. As
the distance increases, a reinforced-​
concrete beam can require such size
and depth that it becomes impractical
to use. A properly engineered beam,
prestressed with highly tensioned
steel strands or cables, can span the
same distance and be thinner, lighter
in weight, and use less concrete without cracking or breaking.1
While Americans constructed
countless reinforced-​concrete structures, they were less curious than a
few pioneering Europeans who championed the theory and use of prestressed concrete. As early as 1904,
Eugene Freyssinet, a French bridge
engineer, pondered the concept of
prestressing to increase concrete’s
BOB FRAME is a senior historian in the Minneapolis office of Mead & Hunt Inc., a national
engineering firm, where he works with the survey, evaluation, and rehabilitation of historic
bridges. He has a PhD in American studies from the University of Minnesota and an MPA
from Harvard’s Kennedy School. RICK MITCHELL AICP is a historic preservation planner in
Mead & Hunt’s office in Austin, Texas. He has spent more than 20 years documenting historic
buildings and bridges and a lifetime experiencing prestressed concrete’s contributions to
American suburbia.
W I N T E R 20 1 4 –1 5 159
resistance to tension. When fully
developed years later, the tensioned
strands of high-​strength steel, combined with high-​strength concrete,
allowed prestressed concrete to withstand much greater tension without
cracking or permanently bending.
Freyssinet was a passionate visionary
and accomplished bridge designer
but was less adept at promoting his
pioneering construction methods as
practical applications.2
It remained for others, particularly Gustave Magnel, an engineering
professor at Belgium’s University
of Ghent, to broaden the appeal of
prestressed concrete by demonstrating how it was at once stronger and
more economical than reinforced
concrete. Magnel studied and tested
Freyssinet’s concepts on prestressing
linear objects such as bridges. Readily
conversant in English, he toured the
United States in 1946 lecturing on
prestressed concrete, and in 1948 published the influential volume Le Béton
Précontraint (Prestressed Concrete).3
The transfer of European technology to the United States and, soon
thereafter, to Minnesota was facilitated by Charles Zollman, a student
of Magnel who emigrated to the U.S.
in 1939 and subsequently translated
Magnel’s book into English. Enthusiastic in promoting his mentor’s
work, in 1948 Zollman joined Preload
Corporation of Boston, then the nation’s leader in designing circular
prestressed-​concrete tanks, an early
adaptation of the technology. After
learning of the City of Philadelphia’s
proposal to construct the Walnut
Lane Bridge high above a road and
creek in Fairmount Park, Zollman and
Preload officials approached Magnel
to prepare plans for a prestressed
bridge. The Belgian professor developed a design with three spans: the
Explaining the concept of prestressed concrete
(Minnesota Highways, Apr. 1960, 6)
160 M I N N E S OTA H I S TO RY
main one, at 160 feet, is long even
by today’s standards. City engineers
gave the approval for the innovative
design, provided Magnel undertook
extensive full-​scale testing of the
prestressed girders. These tests, conducted before hundreds of interested
engineers and officials, successfully
demonstrated that prestressing
concrete with steel wires or strands
allowed girders to span dramatically
greater distances without increasing
their bulk. Magnel’s design, cheaper
than proposed concrete-​arch designs,
won approval from Philadelphia’s
Art Jury, thanks to its clean and functional appearance.4
Completed in late 1950, Walnut
Lane immediately became famous
as the first prestressed-​concrete
beam bridge built in the U.S. Its large
beams would prove to be the best
model for the many bridges needed
as new highway systems expanded
dramatically. According to Zollman,
“No event was more instrumental in
launching the prestressed and precast
concrete industry in North America.”5
Prestressed concrete met the
needs of the era’s construction market. Not only was this type of beam
stronger, longer, and lighter than its
reinforced-​concrete counterpart, it
was a logical candidate for assembly-​
line manufacturing, resulting in
reduced costs and faster production.
Based on his European experience,
wherein every project was customized, Magnel said in 1954 that mass
production of prestressed-​concrete
bridge components was unlikely or
even impossible. U.S. manufacturers proved otherwise. In 1956 the
Highway Research Board reported,
“Standardization of prestressed units
seems to be the trend at the present
time. In the near future, it should
be possible to purchase prestressed
bridge units for various span lengths
in beam and slab sections.” Engineers, architects, and contractors,
Prestressed concrete met the needs
of the era’s construction market.
Not only was this type of beam
stronger, longer, and lighter than its
reinforced-​concrete counterpart, it
was a logical candidate for assembly-​
line manufacturing, resulting in
reduced costs and faster production.
faced with meeting the huge post-​
World War II demand for buildings,
bridges, and other infrastructure, welcomed the new product. Prestressed
concrete also gained popularity as an
alternative to steel, in short supply in
the early 1950s.6
Manufacturing prestressed-​
concrete beams demands a substantial
investment in plant infrastructure,
especially to make large bridge beams.
Stretching the internal wire strands requires a long bed with massive, strong
buttresses at each end to withstand
intense stress. The beds, with concrete
foundations deep in the ground, can
be 300-​to-​500 feet long so that multiple beams can be made at one time,
end to end. Both the design and cost
of these casting or tensioning beds is
substantial. Since the larger beams
for bridges required larger beds than
the shorter components for buildings,
which typically used panels and planks
not found in bridges, plants often
focused on manufacturing one or the
other. Facilities with either specialization usually also offered precast concrete, which was similar but did not
require the new technology. Not every
component had to be prestressed, and
the precast products shared the important advantages of being standardized
and mass-​produced in controlled factory conditions.
With the success of the closely
watched Walnut Lane Bridge, the
fledgling prestressed industry expanded quickly. Massachusetts Institute of Technology hosted the first
national conference on prestressed
concrete in August 1951, and within
months, prestressed bridges began
to be built throughout the country.7
Given bridge designers as the early
champions and highway agencies as
the clients, testing and development
at first focused largely on bridge construction. But architects and builders
soon identified other uses for the new
technology. Prestressed beams and
slabs could increase roof spans, yielding interiors needing fewer support
columns, as well as facilitate rapid
prefabricated construction of cost-​
effective, fire-​resistant buildings.
M
innesota soon discovered
prestressed concrete. At the
second annual concrete conference,
held at the University of Minnesota
in December 1952, a speaker told attendees that only a year earlier he had
predicted that they “were taking part
at the virtual beginning of a major
W I N T E R 20 1 4 –1 5 161
engineering development. . . . which
may well revolutionize construction
practices everywhere.” Recalling earlier technological developments, he
also mentioned “the notable progress
made in this country in prestressed
tank and pipe construction.”8
The speaker might well have been
referring to a 1939 installation at the
St. Paul Regional Water Services’
McCarrons water-​treatment plant.
Architectural and engineering historian Carl Condit identified this as “the
first prestressed concrete structure in
the United States.”9 At the time, Engineering News-​Record reported that the
twin water-​clarifier tanks with unsupported, prestressed-​concrete domes
150 feet in diameter were “said to be
the largest of this type ever built.”10
Still in service today, the domes em-
ployed a prestressing system developed by structural engineer William S.
Hewett, who earlier used his Hewett
System for prestressing concrete to
engineer the interior of the landmark
1932 Washburn Park water tower in
Minneapolis. Despite these early successes, the Hewett System developed
independently of bridge-​related beam
work, although it may have contributed indirectly to the design of the
Walnut Lane Bridge.11
The 1952 conference was the first
in Minnesota to offer presentations
on prestressing technology to the
state’s concrete industry. One speaker
was Ross H. Bryan, an engineer from
Nashville whose firm, Bryan & Dozier, had in 1950 completed a project
that rivaled Walnut Lane for the title
of first prestressed-​concrete bridge
in the U.S. This Tennessee span used
concrete blocks that were joined into
beams with stressed steel strands.
Without mentioning this achievement, Bryan described the block-​
beam design, making key points
that would be repeated regularly by
industry proponents: “The two major
advantages of plant fabrication are
lower costs due to assembly line production and a controlled quality due
to experienced supervision.”12
Among the 200 or so conference
registrants were at least three of Minnesota’s future prestressed-​concrete
pioneers: brothers Norbert and Leonard Soukup from Minneapolis and
Paul Radichel, from a Mankato family of concrete producers. Radichel
would later partner with his brother,
Bill, to establish Spancrete Midwest,
the company responsible for some
of the largest and best-​known Twin
Cities structures of prestressed concrete.13 But first, the Soukup brothers
established a new Minneapolis firm,
Northern States Prestressed Concrete
Company, and completed Minnesota’s
first prestressed bridge. Like Bryan
& Dozier’s Tennessee bridge, their
Goodhue County span was not on a
state highway. And, like the Tennessee engineers, they joined specially
designed and cast blocks into a beam
stressed with a high-​tensile steel
cable manufactured by the Roebling
firm of Brooklyn Bridge fame.
The Soukups cast the blocks and
assembled the beams in their plant
and trucked them to the site. Multiple beams, arranged side by side,
created the bridge, which carried
local traffic from Highway 61 to a Boy
Scout camp outside of Lake City. Although the bridge was small and the
rural location a “narrow back­water
strip” of the Mississippi, the final
Minneapolis’s landmark Washburn water
tower, 1951, its interior an early example of
prestressed concrete
162 M I N N E S OTA H I S TO RY
WHO’S FIRST?
Bryan & Dozier’s small bridge in Madison County, Tennessee,
which was started later than Walnut Lane and was finished
two months sooner, never achieved the acclaim of the Philadelphia “first.” The Tennessee bridge went up so quickly
because it used concrete blocks, tensioned tightly together
with wire strands. This much simpler method employed the
same prestressing principle as Walnut Lane’s components
but instead of casting a single, large beam, it added stressing
to smaller blocks aligned end-​to-​end. There was no need for
massive new casting beds; the blocks could be made in existing
manufacturing facilities.
But this innovation proved to be a sidetrack. The blocks’
maximum length, strength, and capacity could not equal that
of the massive Walnut Lane Bridge beams; use was limited to
smaller bridges with light traffic. Moreover, the advantage of
assembly in 1953 was well attended,
according to a report in Construction
Bulletin: “On hand to observe . . . and
also to acquire information about
the new type of construction, were
Minnesota county engineers, city engineers, county commissioners, representatives of the Portland Cement
Association, and other interested
personnel.”14
Again like Bryan & Dozier’s Tennessee bridge, the Goodhue County
block-​beam construction, though first
in the state, did not become a model
for the future. No other bridges of
similar design and construction have
been identified in Minnesota, and
Northern States Prestressed Concrete
appears to have made no more concrete blocks. Several years later, when
the Minnesota Highway Department
built the first major prestressed-​
concrete bridge on a state highway, it
used beams, not blocks. That bridge
was also fabricated by the Soukups,
but through their new company,
Prestressed Concrete, Inc. (PCI), in
simple construction soon vanished, as larger casting facilities
were established.
Writing on the development of early prestressed-​concrete
construction, long-​time champion Charles Zollman noted, “It
should be recognized that while Bryan’s bridge was the first
prestressed bridge completed in the United States, it was a
block bridge for secondary roads, while the Walnut Lane Bridge
was the first large girder type bridge on a main city parkway.
Thus, both bridges could be considered as firsts in their own
right.”*
*Charles C. Zollman, “Dynamic American Engineers Sustain Magnel’s
Momentum,” in Reflections on the Beginnings of Prestressed Concrete
in America (Chicago: Prestressed Concrete Institute, 1981), pt. 2, p. 51.
Similar block bridges were also built in Michigan, according to Zollman, who does not mention the Minnesota example.
corporated in 1952. This firm soon
became a significant competitor in
the industry.15
S
tate highway engineers
noticed the early bridges built
with prestressed concrete. Iowa’s and
North Dakota’s departments both
completed their first prestressed-​
concrete bridge projects in 1953.
North Dakota’s example was quickly
recognized in Minnesota Highways,
published by the state’s highway department. Would Minnesota be next?
“Although no pre-​stressed bridges
have been built as yet by the Department,” the magazine stated in 1953, “it
is very probable that this type of construction may be utilized within the
immediate future as Minnesota keeps
pace with other states in new and progressive construction materials.” The
“immediate future,” however, would
not arrive for four years.16
Meanwhile, the federal government began transforming the nation
with the Interstate Highway System.
First authorized in 1944, the system
emerged a decade later in the Federal-​
Aid Highway Act of 1956. The act
planned a 41,000-​mile network with
$25 billion ($218.7 billion today) to
be distributed to state highway departments over 13 years. Interstate-​
highway design standards adopted
by the Bureau of Public Roads (predecessor of the Federal Highway
Administration) led to the new freeway concept of controlled or limited
access, with overpasses and interchanges for unimpeded traffic flow. In
1957 Minnesota Highways touted the
efficiency of the new roads, designed
to “free the motorist from the delay
and accident hazard of hundreds of
grade intersections and traffic moving to or from the highway on connecting private driveways.”17 With its
quick start, massive influx of dollars,
and immediate need for countless
bridges, the interstate system created
an instant market for large, heavy-​
duty prestressed bridge beams and
W I N T E R 20 1 4 –1 5 163
girders. Initially, few companies had
the necessary massive casting and
tensioning beds.
Minnesota’s portion of the interstate system envisioned $600 million
in federal aid and three mainline
highways—​I-​35, I-​90, and I-​94—​
connecting the state’s major cities and
heavily populated rural areas. Beltline
highways would encircle the Twin
Cities metro area. The limited-​access
design required construction of an
estimated 675 bridges in the planned
936 miles of freeways, with “no grade
level highway intersections or railroad grade crossings in their entire
length.”18
Simultaneously, the Minnesota
Highway Department began upgrading the state highway system,
thanks to a 1956 state constitutional
amendment that revised highway-​
improvement funding. Major state
highways were upgraded to “expressway” standards, with divided traffic
lanes, limited access, and overpasses
to separate cross-​street traffic. The
rapid upswing in bridge construction
on the interstate and state highways
was remarkable. Interstate bridges,
usually of similar size and design,
created a perfect market for the fledgling prestressed industry’s ability
to mass produce quality-​controlled,
standardized bridge girders. Among
the few qualified Minnesota companies were PCI and the Elk River
plant of The Cretex Companies, Inc.,
or simply Cretex, which had been in
the concrete business for many years
and added prestressing equipment by
1957.19
D
espite the growing nationwide interest in prestressed
concrete, the decision to build Minnesota’s first prestressed-​concrete
highway bridge was surprisingly
routine. It would carry Ninety-​Fourth
Street in Bloomington over the future
164 M I N N E S OTA H I S TO RY
The decision to build Minnesota’s
first prestressed-​concrete highway
bridge was surprisingly routine. It
would carry Ninety-​Fourth Street in
Bloomington over the future I-​35W.
I-​35W, then called Trunk Highway
65. Following longstanding practice,
the designer, Ellerbe and Company, a
prominent St. Paul architectural and
engineering firm, prepared plans and
cost estimates for two alternatives:
steel and concrete. In January 1957,
Ellerbe’s structural engineer E. L.
Gardner concluded: “Calculations
revealed the prestressed type design
would cost less than steel. Also steel
deliveries would not meet contract
timing conditions for the project.
Therefore, it was agreed the final design would be prestressed concrete.”20
It was that simple.
Completed in 1957, Bridge No.
9053—​still its only name—​is significant as the first prestressed-​concrete
bridge on Minnesota’s statewide
highway system, a landmark remaining in service today. To the general
public, however, it is as nondescript
and anonymous as the multitude of
other bridges over I-​35W and its sister
interstate highways—​and that is the
point. Bridge 9053 was followed by
many others of similar size and design because its standardized primary
components were so easy and cost
effective to replicate and maintain.
It represented an ideal solution to a
bridging problem presented thousands of times on modern American
highways and freeways.21
PCI fabricated Bridge 9053’s
prestressed-​concrete beams at the
Soukups’ new facility, built in 1954 in
Roseville, a growing suburban com-
munity on the northern edge of St.
Paul.22 Roseville provided an open,
nine-​acre site near County Road C
and today’s I-​35W, with road and rail
access—​essentially a suburban industrial park. There, the new company
installed a substantial prestressing
facility, signaling its intention to
manufacture large concrete beams,
a far bigger operation than its earlier
concrete-​block beams had required.
After installing its large, in-​ground
casting beds, PCI used them for its
first project, making the prestressed
beams and panels for the building
that enclosed the beds. The Soukups
immediately claimed a national record: these “50-​foot prestressed channel slabs and the 50-​foot prestressed
block girders are the longest of their
type in the United States,” a Minnesota trade journal reported. They also
asserted, “The new installation is
the largest prestressing plant in the
country.”23
Cretex, which also moved into
the prestressed bridge-​beam market, had been founded in 1917 as Elk
River Concrete Products Company
by L. D. Bailey and D. W. Longfellow.
Bailey family members, who ran the
company for decades, oversaw the
creation of The Cretex Companies,
Inc., which eventually included other
plants in Minnesota as well as in
North and South Dakota, Iowa, and
Montana. Guided by Albert Bailey,
the Elk River plant began producing
precast-​concrete members and in the
MINNESOTA’S FIRST
PRESTRESSED-​CONCRETE
STATE HIGHWAY BRIDGE
I-​35 Bridge 9053,
completed in 1957
and still a work
horse today, and
(inset) a peek under
the span, 2014
Engineers describe Bridge 9053 as a “prestressed concrete
beam (PCB) bridge . . . using precast, pretensioned AASHO-​PCI
Type I beam sections,” a design largely replicated in more than
2,800 prestressed-​concrete bridges built in Minnesota since
1957.* The average freeway motorist would find it difficult to
recall anything about Bridge 9053, even after driving under it
many times in daily I-​35W commutes to and from work or a
local mall.
Simple as it is, the bridge exhibits features typical for its
role in the Interstate Highway System, allowing the freeway to
run under a local street. It has two main spans of 60 feet each,
each crossing a pair of I-​35W traffic lanes—​northbound and
southbound—​and a 40-​foot approach span on each side of the
freeway. Although all four spans look alike, the different lengths
point to engineering differences. The longer center spans have
17 prestressed beams, each weighing 12 tons, while the shorter
end spans have only nine 7.5-​ton prestressed beams.
Despite having the newest beam technology circa 1957,
the rest of the bridge uses earlier architectural elements.
The ornamental metal railing continues a design of the 1940s,
soon to be replaced by the familiar streamlined freeway styles
of the 1960s. The large, three-​part concrete blocks at each
railing-​end also reflect styles of the 1930s.
*Dave Dahlberg et al., “Spanning the Land of 10,000 Lakes—​
Minnesota’s Concrete Bridges,” Aspire, Winter 2007, 41.
Installing a prestressed-​concrete beam, 1957 (Minnesota
Commissioner of Highways, Biennial Report 1956–58, 4)
W I N T E R 20 1 4 –1 5 165
1950s quickly moved into prestressed
concrete. Bailey consulted with
Charles Zollman, who advised the
company in the technology of large
tensioning beds. Cretex’s Elk River
plant produced the prestressed beams
for many of the earliest highway
bridges still standing in Minnesota.
Working as a subcontractor, Zollman
prepared calculations for at least one
of them.24
A
lthough initial experimentation and testing of prestressed
concrete focused on bridges and
bridge beams that would satisfy state
and federal safety regulations, the
material soon found other places in
the new suburban world. Beginning
in the 1950s and escalating in the
1960s and afterward, companies
produced the major structural components for a wide array of new buildings dotting the suburban landscape.
Hoping to attract architects and
builders to their products, the new
manufacturers promoted their projects in advertisements demonstrating
their capability to provide what the
market demanded.25
PCI announced that its Roseville
plant would serve Minnesota, North
and South Dakota, Iowa, and western Wisconsin, offering prestressed
channel slabs for floors and roofs,
prestressed girders, and prestressed
bridge members, along with precast columns, walls, manholes, and
custom products. The firm’s first
non-​bridge projects included two
quintessential types of suburban
structure: Westwood, a small, early
shopping center in St. Louis Park,
and a high-​school sports stadium in
Ad promoting Westwood mall’s safety, thanks
to Prestressed Concrete, Inc. (Northwest
Architect, May–June, 1955, 7). The St. Louis
Park Dispatch claimed the fireproof building
was the area’s first.
166 M I N N E S OTA H I S TO RY
Bloomington. The latter, part of the
multimillion-​dollar Bloomington
High School construction project
in 1956, was the first prestressed,
precast-​concrete stadium grandstand in the Twin Cities area. News
accounts and PCI advertising emphasized that the prestressed channel
slabs were “precast inside, under
ideal factory control” and “trucked
18 miles to the job site,” promoting
the advantages of manufacturing
off-​site, unaffected by the unpredictable weather that hampered typical
outdoor concrete construction. The
stadium continues in use at Ninetieth
Street and Queen Avenue South.26
Prestressed-​concrete slabs or
planks emerged as an early modular
building product. Cast in long rectangles, several feet wide and several
inches thick and arranged side-​by-​
side, they formed thin, flat roofs and
floors. To reduce weight, multiple
Westwood in 1957, panorama assembled
by Emory Anderson from three photos,
courtesy St. Louis Park Historical Society
WESTWOOD SHOPPING CENTER
When small shopping centers, only a block or two long, began
appearing in the new 1950s suburban-​edge residential developments, they offered an instant market for easily assembled
precast, prestressed beams and panels. Among Prestressed Concrete Inc.’s first projects was Westwood Shopping Center in St.
Louis Park, which opened in October 1954. Announcing the grand
opening, the St. Louis Park Dispatch stated that it was “designed
in California style” and that “Pre-​stressed concrete roof channels
carried on a steel girder make a fireproof building, first of its kind
in the area.” PCI’s prestressed-​concrete “channel slab” was one of
its early modular units, able to span the length or width of a shop.
The Dispatch’s full-​page spread included a personal note and
photo for each of the new shop owners. The “shiny new center”
tube-​like openings extended the
length of each plank, suggesting their
generic name: hollow core. These
openings easily carried electric lines
and other utilities. Prestressed steel
strands along the bottom of each
panel or plank enabled the longer,
thinner shapes without compromising strength.
Entrepreneurs offered several
patented systems for mass-​producing
these hollow-​core slabs, which used
a smaller casting system with less
intense stressing than did large
bridge beams. Each system typically
included a machine and a license
to produce and sell the hollow-​core
product. Running on beds up to
500 or 600 feet long with taut wire
strands for prestressing, the machine
extruded lengths of hollow-​core con
resembled a small town’s main street: supermarket; apparel,
hardware, variety, and drug stores; dry cleaner, barber, and beauty
shops; and physicians’ and dentists’ offices, along with 150 “ample
well-​lighted” parking spaces. At the grand opening, the Giant Food
Store held a giveaway, including a “‘Broil Quick’ electric fryer,”
Hopalong Cassidy cowboy outfits, and outdoor barbeque table
and grill sets. Westwood itself offered the grand prize: “This newest marvel of the electronic age—​a new RCA Color Television . . .
installed free in the winner’s home.” The Dispatch concluded that
Westwood “is truly a NEIGHBORHOOD shopping center where
friendly, personal service is the order of the day.”
crete slabs in a continuous process. A
saw cut the long slab into the shorter
units specified by the architect or
contractor.
In the 1950s at least three more
Twin Cities companies entered the
market for prestressed, non-​bridge
building components. Two more operated in the region: Zenith Concrete
Products Company in Duluth, and
Gage Brothers in Sioux Falls, South
Dakota.27 But costs for transporting
large components limited the market access for distant firms, favoring
those closest to the areas of concentrated new construction. Whether
newly established or not, all companies entered the prestressed concrete
field at about the same time and all
manufactured both prestressed and
precast components.
Late in the decade, Paul and Bill
Radichel of Mankato created Spancrete Midwest Company and set up
a plant in Osseo (or Maple Grove, as
the successor company identifies its
location today). The brothers had
purchased the second machine made
by Milwaukee manufacturer Henry
Nagy, who had bought the rights to
a German machine for hollow-​core
slabs. After reworking the device
and process for two years, he named
his system Spancrete, establishing
the first use of hollow-​core slabs in
the U.S. in 1954. Four years later he
established Spancrete Machinery
Corporation.28
By summer 1960 the Radichels’
600-​foot casting bed was completed
and their machine began operating.
Spancrete Midwest’s operation was
W I N T E R 20 1 4 –1 5 167
Original Spancrete Midwest plant, Osseo
(Northwest Architect, July–Aug. 1961, 7).
in some ways similar to PCI: its prestressed products formed the walls of
the long, narrow building enclosing
the machine that extruded 600-​foot
prestressed planks that were subsequently cut into the desired lengths.
And, the new Osseo plant stood alone
in a future suburban industrial park,
with its own railroad spur.29
In St. Paul, Molin Concrete Products Company, operating since 1905,
decided to get into the prestressed-​
concrete business for buildings, too.
They acquired the rights to the Flexicore Hollow Core manufacturing process from its Ohio originator, along
with its concrete-​extruder machine.
In 1951 Molin advertised its Flexicore
product, a “long span precast prestressed concrete slab.”30
Wells Concrete Products Company in Wells, Faribault County,
was established in 1951 by Frank
168 M I N N E S OTA H I S TO RY
Balcerzak, who owned the Guaranteed Gravel and Sand Company
of Mankato. Although Balcerzak
showed some early interest in producing beams for Bridge 9053 (he
was adding prestressing capability
to the Wells plant), he instead turned
his attention to the new prestressed
“double-​tee” beam. This form quickly
became a primary structural member, useful for longer spans where
hollow-​core slabs were too short or
too light.31
Wells recommended its slabs for
“schools—​churches—​factories—​
warehouses—​stores” and promoted
the double-​tee for “shopping centers,
super markets, dormitories.” A 1962
advertisement noted the double-​tee’s
fire-​retardant rating, and fire safety
became a selling point for prestressed
concrete building components.32 Architects developed aesthetic interest
by revealing parts of the double-​tee
beam, first exposing beam ends for
a repetitive roofline or cornice detail
and then turning beams from the
horizontal to the vertical as wall panels, transforming the functional tee-​
stems into linear exterior features.33
Northwest Architect,
May–June, 1951, 43
COLUMBIA PARK PICNIC SHELTER
By midcentury, parks founded 50 years earlier faced pressures to expand and modernize for a growing population with new recreational
interests. One response was the Columbia Park Picnic Shelter in northeast Minneapolis, constructed entirely of precast and prestressed
members, all fully visible in a hilltop setting. The University of Minnesota’s School of Architecture held a design competition in 1955, sponsored by the Northeast Lions Club, which funded part of the shelter’s
construction as a gift to the city. Out of 40 entries, John R. Miller’s
student design won. He drew the final plans, which were signed by
Walter K. Vivrett, a professor and registered architect.
Completed in 1955, the shelter employs paired, precast-​concrete,
rigid-​frame bents, each incorporating a column and cantilever roof support for half the span. Prestressed-​concrete planks extend from bent to
bent, comprising the roof and interior ceiling. The rear wall included a
recess for vending facilities, while the front, under the shelter, provided
modern, coin-​operated “automatic electric burners”—​10 cents for 20
minutes and 25 cents for 50 minutes.* No need for smoky outdoor
fireplaces in this fireproof concrete pavilion. Today, the Minneapolis
Park Board considers the shelter’s unaltered, elegant, state-​of-​the-​art
design and construction a “classic modern composition.” It will be carefully restored to meet current accessibility standards in 2015.
Designer John Miller went on to a distinguished career and founded
the Minneapolis architectural firm of Miller, Hanson, Westerbeck, Bell
(today, Miller Hanson Partners). He died in 2003.
*Minneapolis Board of Park Commissioners, Seventy-​Third Annual Report (1955).
PCI advertisement, Northwest Architect, January–February 1958,
and the well-​used shelter with its simple, box-​shaped brick support
building housing restrooms, 2014
W I N T E R 20 1 4 –1 5 169
Double-​tee beam, an aesthetic element in
advertising and construction (Northwest
Architect, Jan.–Feb., 1965, 33).
Zollman found, “Above all, it gave
engineers the power and freedom
to control the internal ‘stresses and
strains’ produced by the application
of exterior design loads.” Looking to
the horizon, the eminent historian
of engineering, David P. Billington,
who studied under Magnel, called
prestressing “the single most significant new direction in structural
engineering of any period in history.
. . . Moreover, the idea of prestressing
opened up new possibilities for form
and aesthetics.”34
Prestressed concrete continues
today as a widely used building material, with additional forms and shapes
added in subsequent decades. The
technology is central to nationally
recognized Twin Cities landmarks—​
some no longer standing—​spanning
more than a half-​century, including
the Metropolitan Sports Center in
Bloomington (erected 1967–68),
Hubert H. Humphrey Metrodome
(1980), Minnesota Timberwolves
Arena (1989), the parking ramps at
the Mall of America, the largest in the
world when they were built (1992),
and the new I-​35W bridge over the
Mississippi River (2008). B
y the middle of the 1960s,
the prestressed-​concrete industry had established itself in
Minnesota, and the firms that would
dominate the state’s industry for
subsequent decades were up and running. Despite the ubiquitous nature
of prestressed concrete, few Minnesotans realized they were surrounded
by a radically new technology:
working, worshiping, or studying in
prestressed concrete buildings, shop170 M I N N E S OTA H I S TO RY
ping in prestressed-​concrete malls,
parking in prestressed-​concrete
ramps, and driving on and under
prestressed-​concrete bridges. Even
fewer knew how this technological
innovation worked and how it had
transformed the world around them
in the decades after World War II.
Two knowledgeable observers
identified the larger contributions
of prestressed concrete. Addressing
its engineering significance, Charles
Notes
The authors wish to thank Kristen Zschomler,
MnDOT Cultural Resources Unit, and Keith Molnau, PE, MnDOT Bridge Office, for their historical and technical reviews. Andrea Weber, PLA,
Minneapolis Park & Recreation Board, provided
detailed information on the Columbia Park Picnic Shelter. Bill Soukup discussed the background of the Soukup family and Prestressed
Concrete, Inc. Gary Pooley, Wells Concrete,
Maple Grove, provided historical materials on
Spancrete Midwest. Mike Johnsrud, PCI Midwest,
and Prof. Cathy French, University of Minnesota
Center for Transportation Studies, offered insights into the prestressed concrete industry.
Secret world of the Metrodome, revealed in Corporate Report: precast and prestressed concrete.
Vomitories? Those are openings onto the seating area from passageways below.
1. For a visual comparison of panel lengths
(roof and floor) with prestressed and reinforced
concrete, see Charles C. Zollman, “The End of
the ‘Beginnings,’” in Reflections on the Beginnings
of Prestressed Concrete in America (Chicago: Prestressed Concrete Institute, 1981), pt. 9, p. 310,
showing the maximum practical length of a
prestressed-​concrete panel to be about 2.5-​to-​3
times that of reinforced concrete. The maximum
length for prestressed-​concrete components
was limited, in part, by the availability of new
trucks to transport them and new cranes to lift
them; see 317.
2. David P. Billington, “Historical Perspective on Prestressed Concrete,” PCI Journal 49
(Jan.–Feb. 2004): 16–17, 20.
3. Shri Bhide et. al., “The Interstate Highway System and the Development of Prestressed
Concrete Bridges,” in 50 Years of Interstate Structures: Past, Present, and Future, Transportation
Research Board, Transportation Research Circular E-​C104, Sept. 2006, 52.
4. Wire strands were fundamental to the
success of prestressed-​concrete components.
See Kenneth Dunker and Basile Rabbat, “Performance of Prestressed Concrete Highway Bridges
in the United States—​The First 40 Years,” PCI
Journal 37 (May–June 1992): 49; Zollman, “End of
the ‘Beginnings,’” 298–307. For the Art Jury evaluation, see Billington, “Historical Perspective on
Prestressed Concrete,” 21–22; Tyson Dinges,
“The History of Prestressed Concrete: 1888 to
1963” (MS thesis, Kansas State University,
2009), 47.
5. Historic American Engineering Record,
Walnut Lane Bridge, Spanning Lincoln Drive &
Monoshone Creek at Walnut Lane, Philadelphia,
Philadelphia County, PA, “HAER PA, 51-​PHILA,
731-​” (1988); Charles C. Zollman, “Magnel’s Impact on the Advent of Prestressed Concrete,” Reflections, pt. 1, p. 7; Bhide et al., “Interstate
Highway System,” 53–54. See also George D.
Nasser, “The Legacy of the Walnut Lane Memorial Bridge,” Structure Magazine, Oct. 2008, 27–31,
noting that after cracks were observed in 1989,
the city replaced the entire original.
6. John J. Hogan, “Cost Comparisons of Prestressed Concrete vs Conventional-​Type Highway
Bridges,” in Some Cost Data on Prestressed Concrete Bridges, National Research Council, Highway Research Board Bulletin 144 (1956), 25. For
the differences between European and American
approaches, see Zollman, “End of the ‘Beginnings,’” 288–89; Dinges, “History of Prestressed
Concrete,” 49–50. The Minnesota Highway Dept.
confirmed, “Construction of prestressed concrete
bridges in Minnesota, begun on a trial basis, was
expanded to offset a shortage of steel”; “Concrete
is ‘Squeezed’ to Extend Its Use,” Minnesota Highways, Apr. 1960, 6.
7. “Milestones of Events and Developments
in North American Prestressed Concrete Industry (1939–1958),” Reflections, pt. 9, p. 361–65. See
also Billington, “Historical Perspective on Prestressed Concrete,” 24.
8. L. H. Corning, “Remarks,” in Second Annual Concrete Conference, Dec. 12 and 13, 1952,
University of Minnesota, Center for Continuation Study, Minneapolis, 42–43, copy in Minnesota Historical Society (MNHS) library. The
document includes the program, list of registrants, and full or partial transcripts of presentations and remarks.
9. Carl W. Condit, American Building Art: The
Twentieth Century (New York: Oxford University
Press, 1961), 191.
10. Leonard N. Thompson, “Sort Water for
St. Paul,” Engineering News-​Record, June 8, 1939,
793. The domes are described in “Principle of
Pre-​Stressed Reinforcement in Design of Dome,”
Concrete 47 (Feb. 1939): 3–4.
11. Thomas W. Balcom, “A Tale of Two
Towers: Washburn Park and Its Water Supply,”
Minnesota History 49 (Spring 1984): 25–26. “The
Hewett System of Reinforced Concrete Construction as Applied to Reservoirs, Tanks and
Domes,” Bulletin A, four-​page pamphlet (Chicago:
William S. Hewett System, n.d.), n.p., includes
Minnesota examples and photographs, copy in
personal collection of Fredric L. Quivik, Michigan
Technological University.
A possible, as yet unexplored, relationship of
Hewett to the pioneers of prestressed-​concrete
bridge development is found in Hewett’s 1943
Patent No. 2,329,719 for a concrete tank. Hewett
assigned the patent to The Preload Co., which
was instrumental in the construction of the Walnut Lane Bridge. This bridge, Zollman wrote, was
W I N T E R 20 1 4 –1 5 171
the first major linear prestressed-​concrete structure in the U.S., as opposed to the earlier circular
tanks and domes; Zollman, “Magnel’s Impact,” 6.
12. Ross Bryan, “Prestressed Block Beam
Units,” in Concrete Conference, 15–16. For a personal account of the bridge, see Ross H. Bryan,
“Prestressed Concrete Innovations in Tennessee,” Reflections, pt. 4, p. 122–39.
13. “Registrants,” Concrete Conference, iii–vi.
14. “Minnesota’s First Prestressed Concrete
Bridge, Near Lake City,” Construction Bulletin,
Aug. 6, 1953, 68–69. Identified only as Bridge No.
L-​0619, Lake City, Goodhue Co., it was replaced
in 2000. The Portland Cement Association actively promoted prestressed concrete and was
instrumental in Bryan & Dozier’s Tennessee
bridge. PCA representatives’ presence in Lake
City indicates national interest in the Minnesota
project.
15. A search of Minneapolis city directories,
1952–57, found no mention of Northern States
Prestressed Concrete. Leonard Soukup was
listed in 1952 as a cement contractor and in 1957
as “plant mgr Prestressed Concrete”; Robert
Soukup, another founder, was a block layer for
Soukup Construction in 1953. For the company’s
incorporation, see Minnesota Secretary of State,
Incorporation Records, filed June 30, 1952, accessed online.
16. L. W. Murray, “Iowa’s First Prestressed
Structure,” Construction Bulletin, Dec. 3, 1953,
52–53, 98; Robert W. Randall, “Pre-​stressed Concrete in North Dakota,” Construction Bulletin,
Nov. 5, 1953, 52–53; Vince Bovitz, “A Preview—​
Bridges of the Future,” Minnesota Highways, Sept.
1953, 3–4.
17. Richard F. Weingroff, “Federal Aid Highway Act of 1956: Creating the Interstate System,”
Public Roads 60 (Summer 1996), www.fhwa.dot
.gov/publications/publicroads/96summer/index
.cfm; “Network Routes Will Have Big Impact,”
Minnesota Highways, Feb. 1957, 6.
18. “Network Routes Will Have Big Impact,”
5. The final number of new bridges built during
the entire period of interstate construction is
uncertain but may have been slightly less than
estimated.
19. Mead & Hunt, Inc., Final Evaluation Report
and Historic Context, Minnesota Bridges, 1955–1970,
prepared for the Minnesota Department of
Transportation, Mar. 2011, 11–12, 41–42; Don
Stoltz, Cretex Times (Edina, MN: Beaver’s Pond
Press, 1997), 104.
20. E. L. Gardner, “Cost Estimate, Bridge No.
9053, 94th St./T.H. 65 for State of Minnesota. . .,”
Ellerbe and Co., Jan. 4, 1957, copy in Correspondence File for Bridge No. 9053, Records Storage,
Minnesota Department of Transportation, St.
Paul (MnDOT). For the cost advantage of prestressed concrete over steel, see Billington, “Historical Perspective on Prestressed Concrete,” 24.
21. On 9053’s status as the state’s first
prestressed-​concrete bridge, see Commissioner
of Highways of Minnesota, Biennial Report, July 1,
1956 to June 30, 1958, 25. A. E. LaBonte, Bridge
Engineer, Minnesota Department of Highways,
172 M I N N E S OTA H I S TO RY
to P. H. Schultz, Assistant Bridge Engineer, South
Dakota Highway Department, Mar. 18, 1957:
“This bridge is our first prestressed concrete
structure;” copy in Correspondence File for
Bridge No. 9053, MnDOT. See also “Pre-​stressed
Beams Introduced,” Minnesota Highways, Sept.
1957, 7.
22. “Pretensioned Concrete Girders Erected,”
Construction Bulletin, Oct. 3, 1957, 35, identifying
PCI as the beam producer. See also 1957 documents in Correspondence File for Bridge No.
9053, MnDOT.
23. “Prestressed Concrete: They Use Their
Own Product,” Construction Bulletin, Jan. 6, 1955,
52–53. The claim is unconfirmed.
24. Stoltz, Cretex Times, 51–55, 103–05; for
The Cretex Companies, Inc. 1920s incorporation
in Delaware, see 42. Elk River Concrete Products
Co. fabricated the prestressed-​concrete beams
for Bridge 6580, which carries Rice St. over
I-​694/Hwy 10 north of St. Paul. Charles Zollman
and Associates, Newtown Square, PA, prepared
the detailed prestressed calculations in 1957–58;
see plan sheet No. 7, Elk River Concrete Products
Co., “Prestressed Concrete Girder Details,” approved Mar. 11, 1958 (with associated correspondence), and Zollman’s 20-​page document (Dec.
1957–Jan. 1958), Correspondence File for Bridge
6580, MnDOT.
25. Kenneth T. Jackson, Crabgrass Frontier:
The Suburbanization of the United States (New
York: Oxford University Press, 1985), particularly
chapter 14, “The Drive-​in Culture of Contemporary America,” 246–71, on the role of the Interstate Highway System. State and local highway
departments and engineers were largely aware
of the new technology, but the non-​bridge market of architects and contractors was more diverse and required wider promotions.
26. “Prestressed Concrete: They Use Their
Own Product,” 52–53; Northwest Architect, May–
June 1955, 7 (Westwood ad); “Prestressed, Precast Concrete Grandstand—​First in Twin City
Area,” Construction Bulletin, Jan. 17, 1957, 33;
Northwest Architect, Nov.–Dec. 1956, 42 (PCI ad).
Bloomington High School was renamed Abraham Lincoln Senior High School in 1965 when
Bloomington Kennedy High School opened. Lincoln was closed in 1982 but the stadium, on the
west side of the athletic field, continued in use
for the Bloomington schools.
27. For Zenith, see “Form Concrete Products
Firm,” Construction Bulletin, July 1, 1954, 78;
Northwest Architect, Jan.–Feb., 1955, 29 (ad). A
Zenith representative attended (with Norbert
Soukup and others) a 1954 course at the University of Minnesota; “To Hold Short Course on
Quality Concrete,” Construction Bulletin, Dec. 30,
1954, 3. For the history of Gage Brothers and
their early years in prestressed concrete, see
www.gagebrothers.com.
28. “The History of Spancrete,” PCI
Historical-​Technical Series, Jan.–Feb. 2005,
17–18, viewed online. For the machine at Spancrete Midwest, see “Spancrete: Strength in Numbers,” Concrete Products, Sept. 1988, n.p. Harry
Edwards, “The Innovators of Prestressed Concrete in Florida,” Reflections, pt. 3, p. 98 (footnote) attributes the first use of hollow-​core slab
in the U.S. to Nagy and Spancrete.
29. “Paul W. Radichel,” obituary, Lake Region
Times, Oct. 28, 2009; “New Spancrete Plant Operates in Osseo” and Spancrete Midwest ad,
Northwest Architect, July–Aug. 1961, 78–79, and 7,
respectively; “Registrants,” Concrete Conference,
iii–vi.
30. Northwest Architect, July–Aug., 1951, 27
(ad); PCI Manual for the Design of Hollow Core
Slabs, 2nd ed. (Chicago: Precast/Prestressed
Concrete Institute, 1998), 1-​1–1-​3; Molin history,
www.molin.com.
31. Letters between Frank Balcerzak and
A. E. LaBonte, Jan. 27–30, 1957, Correspondence
File for Bridge 9053, MnDOT; “Frank Balcerzak,”
in Val Bjornson, History of Minnesota (West Palm
Beach, FL: Lewis Historical Publishing Company,
1969), 4: 598–99.
32. Balcerzak and LaBonte letters; Northwest
Architect, Sept.–Oct. 1962, 10 (ad); “About Us:
History,” wellsconcrete.com/about-​us/history/.
33. For the development of early prestressed
structural members and shapes, see Edwards,
“Innovators of Prestressed Concrete in Florida,”
89–99. Although discussed in a Florida context,
the early development of several basic components applies universally.
34. Zollman, “End of the ‘Beginnings,’” 354;
Billington, “Historical Perspective on Prestressed Concrete,” 14, 29.
The photos on p. 165 (top two) and 169 (bottom)
are courtesy Robert Frame III; p. 171, courtesy
Wells Concrete, Maple Grove. All others, including the magazine images and p. 159 (Metropolitan Airports Commission audio-​visual files, State
Archives) are in MNHS collections.
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