Roebling’s Wire Rope Modernized The D & H Canal


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John A. RoeblingJohn Augustus Roebling celebrated two milestones in June of 1849, his 43rd birthday and the beginning of construction of the Neversink Aqueduct on the Delaware & Hudson Canal. It was the third of the four aqueducts he would design and build for the canal company, and followed the completion of the Delaware and Lackawaxen Aqueducts the previous year.

Roebling (his given name was actually Johann August) was born in Muhlhausen, in Prussia, on June 12, 1806, the youngest son of Christoph Polycarpa Roebling and Fredericke Dorothea Mueller Roebling. He grew up in a world of private tutors, learned the music of Bach and the poetry of Goethe, and according to some sources, built a model of a suspension bridge when he was nine years old that bore a striking resemblance to what would be his most famous work, the Brooklyn Bridge. He gained admission to the prestigious engineering program at the Royal Polytechnic Institute in Berlin, where he studied languages and philosophy as well as architecture, bridge construction and hydraulics. He graduated in 1826, and went to work for the state, as was the requirement at that time, serving three years building roads in Westphalia.

Roebling wanted to build bridges, big bridges, and there was little work of that kind in his native land, so he and his brother, along with a parcel of friends and acquaintances, emigrated to America in 1831. They purchased a large tract of land, and established the community of Saxonburg, near Pittsburgh, Pennsylvania where inexplicably, Roebling, the aspiring bridge builder, began to farm.

Tilling the fields did not satisfy his ambitions for long, and as he witnessed the concerted western expansion of the country over the next few years, he grew increasingly restless, finally returning to engineering in 1837, the same year his wife gave birth to their first child, a son they named Washington Augustus.

Before long, John A. Roebling had begun manufacturing wire rope for use in the suspension bridges he proposed to build. Since America was in the midst of a massive construction phase focusing mainly on canals, it was perhaps inevitable that his first chance to move his designs from paper to stone and concrete and wire came on one of those waterways. In 1844, he won a contract to replace a wooden canal aqueduct across the Allegheny River with his suspended trough design. This first wire rope suspension bridge in America encompassed seven spans of 163 feet each.

NeversinkrivermapRoebling had completed a few other projects by the time the directors of the D&H Canal contacted him in 1846 to ask for a proposal to build two aqueducts at the point along the 108 mile long waterway where it crossed from Pennsylvania into New York. Roebling was no stranger to the canal company, nor was his wire rope an unknown commodity. Two years earlier, the canal had begun purchasing the woven wire to replace the fiber ropes on the planes of the gravity railroad.

Still, there was some discussion required before they decided to award the aqueduct contract to Roebling instead of opting for wooden aqueducts, which would have been considerably cheaper in initial cost.

“At its meeting on December 28, 1846 the board appointed a committee to review the two aqueduct proposals,” writes Larry Lowenthal in his 1997 history of the D&H, From the Coal Fields to the Hudson, “On the next day, (John) Wurts wrote to (Russel) Lord telling him to be ready for a trip to Pittsburgh to examine a suspension aqueduct Roebling had built for the Pennsylvania Canal. A week later, the committee presented a report tentatively favoring the suspension bridge. It compared a wooden aqueduct on stone piers, which was expected to last 36 years, versus the wire supported aqueduct, which was assumed a life expectancy of 60 years. With interest compounded, the wire was calculated to save over $55,000 in its 60 year duration– ‘provided the estimate of time that each will last is correct, that the wire is imperishable, never to be replaced, which the Committee must confess they have much doubt of.’”

Both the Delaware Aqueduct and the Lackawaxen Aqueducts were completed in time for the 1849 shipping season, and the canal company commissioned Roebling to construct two more structures, one over the Neversink River at Cuddebackville and one at High Falls, in Ulster County. Both were finished in time for the 1850 canal season.

The members of the canal company’s building committee were not the only men who doubted the practicality and strength of the Roebling wire rope. Much of the public at large was dubious, as well, and they turned up in large numbers at the opening of the Delaware Aqueduct, probably hoping– or at least expecting– to see it collapse as the first boat crossed.

“There was some apprehension in the crowds on hand when the first boat went across as to whether the bridge would stay up or not,” wrote Manville B. Wakefield in “Coal Boats to Tidewater.” “After all, reasoned the expectant spectators, the water by itself weighed a great deal, let alone a loaded boat too. Great cheers went up when the boat arrived safely on the New York side.”

Although the Lackawaxen, Neversink, and High Falls aqueducts are long gone now, the Delaware Aqueduct has survived to this day, known to most now simply as the Roebling Bridge, and restored and maintained by the National Park Service.

Photo Caption: Above, John A. Roebling; map below courtesy Wikimedia.

2 thoughts on “Roebling’s Wire Rope Modernized The D & H Canal

  1. ray phillips

    A fascinating account of a brilliant and persevering person. Thank you for that.
    W. Roebling brought the wire technology to the Bear Mountain Bridge, innovating on-site weaving of his dad’s rope.

    Reply
  2. Bob Ulrich

    When building his much more famous Brooklyn Bridge, he contracted out for the required “wire rope”, the needed cable. It was only after getting underway, tests uncovered that the supplier was a crook, and had sold him understrength cabling. Rather that start from scratch, he was able to calculate how much stronger the remaining cabe would need to be in order to meet the necessary specifications. The bridge stands today, over 100 years later, and well longer than the much newer Tappan Zee bridge which is being totally restored, as a testament to a genius engineer and his design.

    Reply

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