Leon  Salomon Moisseiff (1872-1943)

Although blamed for the wind-driven collapse of the Tacoma Narrows Bridge in 1940, he remains respected for showing how to make long-span bridges more graceful. In 1909, as designer of the Manhattan Bridge, Moisseiff introduced "deflection theory" from Europe. Latvian-born, he became the world's foremost authority on suspension-bridge engineering and consulted on most major long-span bridges in the U.S. He stiffened the two-lane, 2,800-ft-long Tacoma Narrows Bridge, the world's most slender for its length and width, with a mere 8-ft-deep plate girder rather than a truss. He died three years after the disaster, but was still so esteemed that the American Society of Civil Engineers established the Moisseiff Award fund.

Leon Moisseiff, the designer of the bridge, said, "I'm completely at a loss to explain the collapse," which is true, considering he did not anticipate the need to calculate for aerodynamic forces on the bridge design. Even the FWA reported after the collapse that the bridge construction was the most suitable for its uses, economics, and location. Therefore, the engineers cannot be placed totally at fault; their understanding was incomplete. After the collapse of the bridge, engineers realized that there is a need to fully understand all the forces acting on their design. They also learned in hindsight the dangers of exceeding a design paradigm. The Tacoma Narrows Bridge was the most flexible bridge of its time, exceeding previous bridge's designs in terms of the ratios between length, depth, and width. Whether or not they knew it at the time, the designers were taking a risk by trying something completely new. In this case, they failed, but in their failure, they probably contributed more to engineering science than they would have had they succeeded.


Leon S. Moisseiff  was awarded the Egleston Medal Award in 1939, The highest award of the Columbia Engineering School Alumni Association.

The Egleston Medal is awarded to a living alumnus/a of SEAS in recognition of distinguished engineering achievement. The award is given for a notable application of an engineering principle; the development of an industry, process, technique, or material; or the furtherance of a specific branch of the profession. It was established in 1939 to honor the memory of Thomas Egleston, founder in 1864 of the Columbia College of Mines, from which developed Columbia University School of Engineering and Applied Science.



Othmar Herman Ammann

b. March 26, 1879, Schaffhausen, Switz.

d. Sept. 22, 1965, Rye, N.Y., U.S.

engineer and designer of numerous long suspension bridges, including the Verrazano-Narrows Bridge over New York harbour (see photograph), at its completion (1965) the longest single span in the world.

In 1904 Ammann immigrated to the United States, where he helped design railroad bridges. Joining the Pennsylvania Steel Company the following year, he worked on the Queensboro Bridge, New York City. During his term (1912-23) as chief assistant to the noted bridge engineer Gustav Lindenthal, he helped design and build the Hell Gate (steel arch) Bridge, New York City, and the Ohio River Bridge, Sciotoville, Ohio.

In 1923 Ammann set up his own engineering firm in New York City, and the following year the Port of New York Authority agreed to finance his proposed bridge across the Hudson River between New Jersey and upper Manhattan. When finished in 1931, the George Washington Bridge was the longest in the world, almost double the length of the previous record holder.

Ammann was chief engineer of the Port of New York Authority from 1930 to 1937 and director of engineering from 1937 to 1939. As chief engineer, he was in charge of building the Bayonne Bridge over the Kill van Kull, N.J., the Outerbridge Crossing and Goethals Bridge across Arthur Kill, and the Lincoln Tunnel under the Hudson River. As director of engineering, he directed the building of the Bronx-Whitestone Bridge and the Triborough Bridge, New York City. He also sat on the Board of Engineers in charge of San Francisco's Golden Gate Bridge, which opened in 1937.

In 1939 Ammann returned to private practice, designing bridges and highways in New Jersey and New York. He served on the three-man board that investigated the Tacoma Narrows Bridge aerodynamic failure in 1941. In partnership with Charles S. Whitney from 1946, Ammann designed the Throgs Neck Bridge, New York City, the Dulles International Airport, outside Washington, D.C., and three buildings for New York City's Lincoln Center for the Performing Arts.

After investigating the 1940 collapse of the too slender Tacoma Narrows Bridge, Ammann made a major contribution to graceful, suspension bridge design. As chief engineer of the Port of New York Authority, he developed a tubular stiffening framework, devised for the slender, then-record-span 4,260-ft Verrazano Narrows Bridge that opened in 1965. Decades earlier, he set an example that encouraged others to permit greater flexibility of stiffening girders. While doubling the record for the length of any previous bridge, Ammann designed the 3,500-ft George Washington Bridge without stiffening trusses. Opened in 1931, it was stiffened up with a second roadway in 1962.





John A. Roebling

b. Muhlhausen, Thuringia 1806
d. New York 1869

Creator of the Suspension Bridge

Roebling Online History Archive


In 1831, Roebling came to America. He purchased 25 acres of land in the Dutch country of Pennsylvania and became a farmer. After a few years of farming, he decided to look for engineering work with the hopes of one day building a suspension bridge. He found work employing his drafting and engineering skils for various canal and companies. In 1844, Roebling won a commision to replace an aqueduct over the Alleghency River. During 1846-47, he completed the Monagahela River wire suspension bridge. In the following year, he completed a suspension bridge over the Lackawaxen River. It took Roebling many years to perfect his wire rope and the design for the construction of suspension bridges. John Roebling designed and started building the Brooklyn Bridge. He died of lock jaw when his foot became infected after being crushed by a ferry boat before he could finish the bridge. The bridge was completed by his son, Washington Roebling. In his years in America, Roebling became famous for his wire rope.

John Augustus Roebling





As a father and son, John and Washington Roebling were the foremost American engineers of suspension bridge construction in the nineteenth century. John Roebling was born in Muhlhausen, Thuringia in 1806. While in school he developed an interest in both metaphysics and in bridge building. He graduated with a degree in civil engineering from the Royal Polytechnic Institute of Berlin in 1826.

In 1831 Roebling and his brother immigrated to Pennsylvania to farm. When this venture failed, Roebling accepted the position of Pennsylvania state engineer. In this position, he surveyed and supervised the construction of canals, locks, and dams.

In 1841 Roebling invented the twisted wire-rope cable, an invention which foreshadowed the use of wire cable supports for the decks of suspension bridges. Six years later he established a factory in New Jersey for the manufacture of this cable. Because the cable could support long spans and extremely heavy loads, Roebling quickly gained a reputation as a quality bridge engineer.

John Roebling completed dozens of major works and designed the largest bridge span of his lifetime. A prolific writer, bridge builder and theorist, Roebling's chief published work was Long and Short Span Railway Bridges.

Roebling died in New York in 1869 of injuries sustained on the site of a bridge construction.

Adolf K Placzek. Macmillan Encyclopedia of Architects. Vol. 1. London: The Free Press, 1982. ISBN 0-02-925000-5. NA40.M25


Colonel Washington A. Roebling


Washington Augustus Roebling, 1870


b. May 26, 1837, Saxonburg, Pa., U.S.
d. July 21, 1926, Trenton, N.J

U.S. civil engineer under whose direction the Brooklyn Bridge, New York City, was completed in 1883; the bridge was designed by Roebling with his father, John Augustus.

After graduating from Rensselaer Polytechnic Institute, Troy, N.Y. (1857), he joined his father in the work of building suspension bridges. The Civil War, however, intervened, and he served in the Union Army, rising to the rank of colonel by war's end, after which he returned to the construction business. His father put him in charge of the construction of the enormous masonry towers that supported the cables of the Cincinnati-Covington Bridge (1865-67) and then sent him to Europe to study new methods for the sinking of the foundations on which the granite towers of the Brooklyn Bridge were to stand.

On his father's death in 1869 he was asked to serve as chief engineer on the Brooklyn Bridge and immediately began work on the foundations for the two towers. The use of pneumatic caissons (watertight chambers) was still in a somewhat experimental stage, and what happened to men working in compressed air at the bottom of the caisson was not yet fully understood. Though every precaution was taken there were more than a hundred cases of decompression sickness (the "bends") when men were brought up too rapidly. There were also the usual difficulties of fires and breakdowns, as well as so-called blow-outs that shot mud and water into the air. Like his father, Colonel Roebling felt he had to inspect every detail of the work. One day he remained 12 consecutive hours in the compressed-air chamber, finally being carried out unconscious. In those days there was little understanding of the amount of time needed for slow decompression. The nitrogen bubbles in the bloodstream could paralyze a man for life. His health was permanently affected, and, though he lived to be almost 89, the Brooklyn Bridge was his last major undertaking. The bridge, opened in 1883, took 13 years to complete.