Ralph
Modjeski was one of the twentieth century's most accomplished bridge designers.
The Polish-born engineer is known as "America's greatest bridge builder"
for his many suspension, truss, steel arch, and bascule designs.
Early Life
Ralph
Modjeski was born Rudolph Modrezejewski on January 27, 1861 in Bochnia, a city in
southern Poland
that was then part of the Austrian Empire. His father, Gustav Sinnmayer
Modrzejewski, died in 1865. His mother, Helena Opid Modrzejewska, was a
Shakespearean actress whose autobiography describes how young Rudolph spent
hours at the piano, mastering Mozart and training to become a classical
pianist.
From Stage Manager to Engineer
In 1876,
Helena and Rudolph left Poland
along with Henryk Sienkiewicz, winner of the Nobel Prize for literature; and
Wlodzimierz Krzyzanowski, a brigadier general. The expatriates lived for a
while at a utopian community in Anaheim, California, but Helena and Rudolph eventually moved to San Francisco. Before
Helena Modrzejewska made her debut on the American stage, a director suggested
shortening the family name to Modjeski. In turn, Rudolph also changed his first
name, becoming Ralph Modjeski.
For several years, Ralph Modjeski worked as the stage
manager for his mother's troupe during tours across the United States and Europe.
He continued his music lessons as time allowed, but also developed a new
interest – engineering. Modjeski failed his first entrance examination to France's École
des Ponts et Chaussées, but applied again in 1881. Four years later, he
graduated with a degree in civil engineering. He returned to the United States
and, two years later, became an American citizen.
A Trio of Bridge Designers
Following a stint as a bridgework
inspector, Ralph Modjeski found work with George Shattuck Morrison, an American
bridge builder whose railroad spans would cross the nation's mightiest rivers.
After helping Morrison build the Union
Pacific Railroad
Bridge at Omaha,
Nebraska, Modjeski became chief draftsman and
on-site engineer for Tennessee's Memphis Bridge. Modjeski's success in the
American South then led to an opportunity in Illinois,
where he helped design the 2,800-ft long Thebes Bridge.
Although Ralph Modjeski deserves credit for the
bridge at Thebes,
he was aided by Morrison and assisted by Alfred Noble, a past president of the
American Society of Civil Engineers. Together, the bridge builders used the Warren truss and the Pratt
truss to develop standard designs for steel railroad spans. When used with
shorter spans, the Warren
truss consists of sloping members that form a series of alternating "A" and "V"
shapes between the top and bottom chords. When used with longer spans, however,
the Warren
truss also incorporates vertical members for added strength. The Pratt truss resembles
the longer version of the Warren
truss, but slants all of its diagonal members in and towards the center of the
span.
New Challenges, Improved Designs
Modjeski's truss designs were important, but his use
of rivets and K-braces were ground-breaking. During the late nineteenth century,
railroad trusses were connected with pins so that bridge builders could perform
more work in their shops and spend less time in the field. Following the
collapse of the Quebec
Bridge in 1907, however, civil
engineers were forced to re-consider their methods. The replacement structure
that Modjeski built used sturdy rivets instead of pins, and incorporated K-shaped
braces for added stability.
Ultimately, the new cantilever-style Quebec Bridge
was so impressive that Modjeski was entrusted with the design of a steel
suspension bridge over the Delaware River. Regarded
as "the first distinctly modern suspension bridge built on a grand scale," the Benjamin
Franklin Bridge (as the structure is now known) used pneumatic caissons to
secure the bridge to the bedrock beneath the river floor, and steel towers whose
flexibility permitted movement with the supporting cables. Improvements in
wire-drawing also allowed Modjeski and bridge architect Paul Cret to use only
two main cables instead of four.
America's Greatest Bridge Builder
After completing the Delaware
River Bridge in 1926,
Ralph Modjeski designed the Tacony-Palmyra
Bridge in northeastern Pennsylvania and the Mid-Hudson
Bridge in upstate New York. In partnership with Frank M. Masters,
"America's greatest bridge
builder" also designed spans over Pennsylvania's
Susquehanna River and Michigan's
St. Clair River. This latter waterway formed the boundary between the United States and Canada,
and required Modjeski to overcome considerable bureaucratic hurdles in building
the Blue Water Bridge.
For his many accomplishments, Ralph Modjeski was awarded the prestigious John
Fritz Gold Medal, an honor which some regard as America's highest award for
engineering. Modjeski was also granted honorary doctorates from several academic
institutions, and named a Knight of France's Legion of Honor. Fittingly, the
Polish-born engineer was also awarded his homeland's Grand Prix Medal at the Exposition
and Science in Poznan.
Ralph Modjeski died in Los Angeles California
on June 26, 1940
Resources:
http://en.wikipedia.org/wiki/Ralph_Modjeski
http://www.polishamericancenter.org/Modjeski.htm
http://en.structurae.de/persons/data/index.cfm?id=d000386
http://www.polishamericancenter.org/Modjeski_Tribute.html
http://en.wikipedia.org/wiki/Bochnia
http://www.polishcultureacpc.org/modjeski/RMresume.html
http://www.blairhistory.com/landmarks/blair_bridge/morison.htm
http://www.globalsecurity.org/military/library/policy/army/fm/3-34-343/gloss.htm
http://pghbridges.com/termsBrg.htm
http://www.matsuo-bridge.co.jp/english/bridges/basics/truss.shtm
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