Great Engineers & Scientists Blog

Great Engineers & Scientists

In 1676, Sir Isaac Newton wrote "If I have seen further it is by standing on ye shoulders of Giants." In this blog, we take Newton's words to heart, and recognize the many great engineers and scientists upon whose shoulders we stand.

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Ralph Modjeski: America’s Greatest Bridge Builder

Posted October 11, 2007 10:00 AM by Steve Melito

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 reconsider 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



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Re: Ralph Modjeski: America’s Greatest Bridge Builder

10/12/2007 1:00 AM

Isambard Kingdom Brunel, the man that invented the "living-bra!"

"Perplexity is the beginning of dementia" - Professor Coriolus
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Re: Ralph Modjeski: America’s Greatest Bridge Builder

10/12/2007 2:04 PM

Is Brunel "Britain's Greatest Bridge Builder" then?

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