TODAY IN HISTORY

Roebling and the Brooklyn Bridge

On June 12, 1806, John A. Roebling, civil engineer and designer of bridges, was born in Mühlhausen, Prussia. The Brooklyn Bridge, Roebling’s last and greatest achievement, spans New York’s East River to connect Manhattan with Brooklyn. When completed in 1883, the bridge, with its massive stone towers and a main span of 1,595.5 feet between them, was by far the longest suspension bridge in the world. Today, the Brooklyn Bridge is hailed as a key feature of New

York’s City’s urban landscape, standing as a monument to progress and ingenuity as well as symbolizing New York’s ongoing cultural vitality.

John A. Roebling came to design suspension bridges through his earlier work on canals. Trained as an engineer at Berlin’s Royal Polytechnic Institute, Roebling emigrated to the United States in 1831, helping to settle the farming community of Saxonburg in western Pennsylvania. He was soon employed to work on the extensive canal system then being built for travel across the state. One element of that system was a series of inclined planes used to haul barges along railway tracks over steep terrain. Troubled by their reliance on dangerously breakable hemp rope, in about 1839, Roebling turned his efforts toward the manufacture of strong but flexible wire rope as an alternative. Roebling’s invention soon was being used by the Allegheny Portage Railroad; he received a patent for his “new and Improved Mode of Manufacturing Wire Ropes” in 1842.

Roebling quickly found additional uses for his invention. His first wire cable suspension bridge (1844-45) was a wooden aqueduct that carried Pennsylvania’s main east-west canal above and across the Allegheny River into downtown Pittsburgh. He received additional patents in 1846 and 1847. Roebling’s Delaware Aqueduct (184748) followed closely on his earlier design and is the oldest surviving suspension bridge in America. In pursuing these projects, Roebling developed a viable method of spinning the heavy wrought iron wire cables on site, as well as a simple and secure way to anchor them — both of which made the construction of long suspension bridges feasible.

Roebling moved his family to Trenton, New Jersey, in

1848, where he established a business manufacturing twisted wire cable for a wide variety of engineering applications. (This successful business continued as the

John A. Roebling’s Sons Company through the mid-20th century.) Bridges that Roebling designed, such as the Niagara River Gorge Bridge (1855) and Pittsburgh’s Sixth Street Bridge (1859) were admired for their technical innovation as well as their expressive design.

His Cincinnati & Covington Suspension Bridge (1856-67), which was itself the longest suspension bridge of its time, served in part as a prototype for his monumental East River project.

New Yorkers had long desired a bridge directly linking Manhattan and Brooklyn, which were by 1860 the country’s first and third largest cities, respectively. Roebling’s first plan for an East River bridge, developed in the 1850s, was nearly as ambitious as the one that was eventually built. In late 1866, a private Brooklynbased venture called The New York Bridge Company was founded (with the infamous

Boss Tweed as a trustee). Roebling — whose Cincinnati bridge had just opened to great acclaim — was soon hired as chief engineer.

Roebling planned his Manhattan and Brooklyn Bridge (its most official name at the time) to be made with newly available steel wire, which allowed it to be stronger, larger, and longer then any bridge yet built. The two-tier design offered cable car transportation as well as roadways for vehicles and an elevated pedestrian promenade. The project soon met with full approval, receiving New

York state funding as well as Congressional authorization by 1869.

In July 1869, soon after construction of the Brooklyn Bridge began, John Roebling died from tetanus contracted when his foot was crushed in an accident on site. Almost immediately, Roebling’s 32-year-old son and partner, Washington A. Roebling, was named chief engineer in his place. Other mishaps, including an explosion, a fire, contractor fraud, and Washington Roebling’s own illness, hampered timely completion of the project.

Pressurized pneumatic caissons, eventually sunk to a depth of 44.5 feet on the Brooklyn side and 78.5 feet on the Manhattan side, provided dry underwater space for workers to dig the bridge’s foundations down to solid rock. Alas, working in the caissons often brought on “the bends” — a serious medical condition caused by moving too quickly out of a high-pressure atmosphere. Washington Roebling himself was among the many workers permanently impaired (or in some cases killed) by this little-understood “caisson disease,” now known to be decompression sickness. As a result of his disability, after 1872, Washington Roebling’s wife, Emily, became actively involved in supervising construction — carrying messages and instructions back and forth between the bed-ridden chief engineer and his staff.

In 1876, with the bridge towers completed to their final height of 277 feet above water, construction of the four great cables that suspend the bridge’s roadway began. The longest and heaviest cables that had ever been made (containing over 14,000 miles of wire weighing almost 3,500 tons) were created using the same method that John A. Roebling had patented some 30 years before. Because of the scale of the operation, just making the cables took 18 months. When it came time to finally build the bridge’s deck, steel-manufacturing technology had improved so much that it was possible to use steel instead of iron, further strengthening the bridge. With the deck floor in place, the bridge’s supporting trusses were assembled and the visually stunning diagonal stays that stabilized the cable system were installed.

The Brooklyn Bridge opened to citywide celebration on

May 24, 1883. Over the next hundred years, the bridge became part of the romance of New York City. Poets and artists have long found the bridge a worthy subject and the Brooklyn Bridge continues to serve as the backdrop in countless photographs and films.

On September 11, 2001, the Brooklyn Bridge took on a different form of symbolism. In the wake of the attacks on the World Trade Center, thousands of pedestrians used the bridge to escape Lower Manhattan on foot.