|PDH Online Course Description||PDH Units/
Learning Units (Hours)
It’s one of the greatest bridges - in a city known for great bridges - and the masterpiece of a legendary bridge engineer. Intended to be the “Eastern Entrance” to New York City (via the treacherous Hell Gate Strait), the Hell Gate Arch Bridge is one of three spans (Hell Gate, Little Hell Gate and Bronx Kill) comprising the “East River Bridge Division” of the New York Connecting Railroad. Conceived by Alexander J. Cassatt, President of the Pennsylvania Railroad (PaRR), it would be the means by which the “Pennsy” would gain access to America’s great metropolis. The grand scheme called for a pair of tunnels under the Hudson River whereby electric trains would serve a great “Pennsylvania Station” on Manhattan’s West Side. Acquired by the PaRR in 1900, the Long Island Railroad would be integrated into the PaRR system via a pair of tunnels under the East River, also accessing Penn Station. Another pair of tunnels under the East River would serve passenger trains from New England and points north while freight trains would traverse Queens and Brooklyn to a Bay Ridge (Brooklyn) Terminal and, by train ferry, connect to the PaRR’s Greenville Terminal, in New Jersey.
The key to it all was the successful spanning of Hell Gate Strait. The man selected by Cassatt was an Austrian immigrant whose first job in America was as a mason, working on the 1876 Centennial Exhibition in Philadelphia. His technical prowess soon led him to a career that, by the turn-of-the-century, recognized Gustav Lindenthal as America’s premier bridge engineer. Considering several bridge types, Lindenthal recognized that a monumental arch would be most appropriate. So impressed was Dr. J.J.C. Bradfield upon observing the Hell Gate Arch under construction, he decided an arch would be more appropriate than the cantilever he was planning for spanning Sydney Harbor. Lindenthal, who had served as NYC’s first Bridge Commissioner, assembled a dedicated and capable team of assistants. A young Swiss named Othmar H. Ammann, would serve as his First Assistant. They had met during the construction of the Queensboro Bridge, while Lindenthal was NYC Bridge Commissioner. The two men’s destinies would, thereafter, be intertwined. Another engineering staff member was David B. Steinman, who would go on to become one of the great bridge engineers of the 20th century, along with Ammann. It was Steinman who oversaw the historic “True Stress” measurements of the Hell Gate Arch.
The design thoroughly considered and perfected, construction began in 1912 and was completed in 1917. Because the Hell Gate Strait was/is an important navigable waterway, navigation could not be hindered in any way. Thus, back-stay trusses would restrain each half of the arch from rotating on its pair of hinges as a pair of creeper cranes constructed the arch-truss (while ascending the upper chord/s). Upon closing of the arch (in October 1915), the arch became self-supporting and the suspenders and road deck could be installed (as the creeper crane/s descended each arch-half). The result was a four-track configuration that could handle the heaviest trains while traveling at full speed. To Astoria, Queens (on the Long Island side), the image of the bridge has become symbolic of the neighborhood itself. The natural stepping stone both Randalls and Wards Island provided in connecting Long Island to the Bronx would be used once again, this time for a vehicle bridge. The Triborough Bridge (now known as the Robert F. Kennedy Bridge) would parallel the Hell Gate Bridges and Viaducts with an additional connection to Manhattan via a complex “Flying Junction” and the Harlem River Lift Bridge. Completed in 1936, Gustav Lindenthal’s fears that his greatest work would be marred by “a suspension bridge of cheap pole and washline architecture,” in close proximity, went unrealized.
This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.
NY PE & PLS: You must choose courses that are technical in nature or related to matters of laws and ethics contributing to the health and welfare of the public. NY Board does not accept courses related to office management, risk management, leadership, marketing, accounting, financial planning, real estate, and basic CAD. Specific course topics that are on the borderline and are not acceptable by the NY Board have been noted under the course description on our website.
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