Monday, January 14, 2013

The High Bridge and Tower in New York City

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On January 11, 2013, Mayor Michael Bloomberg broke ground for the $61 Million redevelopment project on the High Bridge,  New York's oldest bridge spanning the Harlem River onto Manhattan island.  The project is expected to be completed in the summer of 2014.  The High Bridge was part of the Croton Aquaduct System which I wrote about a few days ago.

The High Bridge is now a steel arch bridge, with a height of almost 140 feet over the Harlem River. The eastern end is located in The Bronx, and the western end is located at Highbridge Park, in a section of Manhattan island called Washington Heights.
Although High Bridge has been closed to all traffic since the 1970s, it remains the oldest surviving bridge in New York City although, in fact, most of the current bridge dates from only 1928.

Interior staircase of the High Bridge Water Tower
Originally designed as a stone arch bridge, the High Bridge had the appearance of a Roman aqueduct. Construction on the bridge was started in 1837, and completed in 1848 as part of the Croton Aqueduct, which carried water from the Croton River to supply the  city of New York some 10 miles to the south.  High Bridge has a length of well over 2,000 feet. It was designed by the aqueduct's engineering team, led by John B. Jervis

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High Bridge with Original Pillars (as seen in 1890) viewed from the Bronx toward Manhattan.
The High Bridge Tower can be made out in the distance near the terminus point of the bridge.
The Croton Aqueduct had to cross the Harlem River at some point, and the method was a major design decision. A tunnel under the river was considered, but tunneling technology was in its infancy at the time, and the uncertainty of pursuing this option led to its rejection. Don't forget the problems with building the casons for the Brooklyn Bridge decades later further south on the East River.   A low High Bridge  would have been simpler, faster, and cheaper to construct. When concerns were raised to the New York Legislature that a low bridge would obstruct passage along the Harlem River to the Hudson River, a high bridge was ultimately chosen.
In 1928, in order to improve navigation in the Harlem River, all of the masonry arches of the central part of the bridge that spanned the river were demolished and replaced with a single steel arch of about 450 feet. Of the masonry arches of the original 1848 bridge, only one survives on the Manhattan side, while ten survive on the Bronx side.
Officials were thinking of closing the bridge in the mid 1960s due to disrepair, then in 1970 a pedestrian threw a rock from the bridge onto a tour boat, and the bridge was closed.  On January 11, 2013 the mayor's office announced the bridge would reopen for pedestrian traffic by 2014. 

Three Harlem River bridges: High Bridge (showing the steel arch that replaced the original masonry spans), nearest; Alexander Hamilton Bridge (part of I-95); and the Washington Bridge, farthest. Washington Heights is left and the Bronx on right)

From the Bronx
The High Bridge was part of the first reliable and plentiful water supply system in New York City. As the City was devastated by cholera (1832) and the Great Fire in 1835, the inadequacy of the water system of wells-and-cisterns became apparent. Numerous corrective measures were examined. In the final analysis only the Croton River, located in northern Westchester County was found to be sufficient in quantity and quality to serve the needs of the City. The delivery system was begun in 1837, and was completed in 1848.
The Old Croton Aqueduct was the first of its kind ever constructed in the United States. The innovative system used a gravity feed, dropping 13 inches  per mile and running 41 miles into New York City through an enclosed masonry structure crossing ridges, valleys, and rivers. University Avenue in The Bronx was later built over the southernmost mainland portion of the aqueduct, leading to the bridge. The High Bridge soars 138 feet above the 620-foot wide Harlem River, with a total length of 1,450 feet. The bridge was designed with a pedestrian walkway atop the Aqueduct and was not used for vehicular traffic. Though the carrying capacity was enlarged in 1861-62 with a larger tube, the bridge, obsolete due to opening of the New Croton Aqueduct, ceased to carry water in 1917. In the 1920s the bridge's masonry arches were declared a hazard to ship navigation by the United States Army Corps of Engineers, and the City considered demolishing the entire structure. Local organizations called to preserve the historic bridge, and in 1927 five of the original arches across the river were replaced by a single steel span, the remaining arches were retained.

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