|
Today,
a lesson in shameless grandeur and simplicity. The University of Houston's
College of Engineering presents this series about the machines that make
our civilization run, and the people whose ingenuity created them.
We call the confluence of the Harlem and
the East Rivers in New York City Hell's Gate. Dramatic, I suppose, but why
not! A bridge opened over Hell's Gate in 1917. It's an arch of iron
girders. The arch thickens at each end. It thins toward the center. You
get a feeling of buoyancy looking at it.
Othmar Ammann, who designed the bridge,
caught Hell for it. This, says writer Christopher Bonanos, was an age of
ornament, gravity, solidity, and dignity. Ammann's design was imperfect in
some ways. But its simplicity, lightness, and freedom signaled a new era
in design.
Ammann had finished an engineering degree
in Switzerland in 1902 and had come here soon after. Now -- in 1930 -- he
was hard at work on two really grand bridges that're sure to carry his
name far into the 21st century.
One was the Bayonne Bridge -- an expanded
version of his Hell's Gate triumph. It's a huge graceful arch of open
structural steel. The other was the longest suspension bridge up to that
time. It's the George Washington Bridge with its 3500-foot span.
The George Washington Bridge also has open
structural steel towers. At first they were to've been faced with stone,
but the Depression required cost cutbacks. Had Ammann meant all along for
that great steel span to stand naked at the north portal of New York City?
He never would say.
Whatever Ammann's intentions, the outspoken
modern architect Le Corbusier called it the most beautiful bridge in the
world. Meanwhile, Ammann kept tying New York to land. He built the
Bronx-Whitestone Bridge. He built the Throgs Neck Bridge.
When Ammann died at 86 he'd just finished
his last masterpiece. For the second time he'd given us the world's
longest suspension span. The Verrazano Narrows Bridge is a plain study in
grace, with a 4300-foot central span.
He created a radical new deck design for
the Verrazano Bridge to keep it from galloping in the wind. The deck thins
toward its edges to guide wind around it. Ammann's work was meticulous.
The towers are an inch and a half wider at the top to keep gravity's force
dead-vertical -- despite Earth's curvature.
So this remarkable 19th-century engineer
left his stamp on bridge-building down through the 20th century. He helped
shape a new attitude toward design. Ammann was born ten years before the
Eiffel tower was built. And he showed us the steel at the heart of design.
Writer Bonanos says that he expressed structure without shame. It is that
shameless joy in naked function that touches us. It is the simple grandeur
of open steel against the sky.
John Lienhard
The massive beauty and advanced technology
of the Hell Gate Bridge (more properly the New York Connecting Railroad
Bridge) contrast sharply with nineteenth-century descriptions of the
channel that it spans. Named for the dangerous rocks and perilous waters
at the confluence of the East and the Harlem Rivers, Hell Gate is
surrounded by Manhattan, Queens, and three islands: Wards, Randalls, and
Roosevelt (formerly called Blackwell's, then Welfare). Philip Hone (1780
-1851), writing of an 1844 visit there, described "the delightful
scene: the clumps of fine old trees clothed in the gorgeous foliage of
autumn, the lawn still bright and green, the mild, refreshing breeze, the
rapid waters of Hell Gate covered with sailing vessels and steamboats -all
combined to present a picture of consummate beauty."
The construction of the Pennsylvania
Railroad tunnel under the Hudson River and into Pennsylvania Station
replaced the time-consuming and expensive water route for New York -bound
passengers and freight from New Jersey and points south. Hell Gate Bridge
-from the Sunnyside Yards in Queens across the Hell Gate to Wards Island,
then across the Little Hell Gate to Randalls Island, and then over the
Bronx Kill to the Bronx -was built to complete the linkage of the New
York, New England, and Long Island rail lines with the Hudson River
crossing. Together, tunnel and bridge created a direct route over the
Bronx Kill to the Bronx.
The longest, heaviest, strongest steel arch
bridge in the world at that time and the only four-track long-span
railroad bridge ever built, Hell Gate Bridge marks the apogee of American
railroad power and prosperity. Government regulation, poor management, and
a proliferation of alternative methods of transportation -private cars,
trucks, buses, and airplanes -eventually undercut the railroad's primacy.
Engineer Gustave Lindenthal (1850 -1935)
and architect Henry Hornbostel (1867 -1961) had previously been
responsible for the redesign of both the Manhattan and Queensboro Bridges.
Lindenthal, who served in 1902 -1903 as Commissioner of Bridges, firmly
believed that a bridge could be both technologically sound and
aesthetically pleasing. Despite his accomplishments and success,
Lindenthal probably had no formal training in his chosen profession but
apparently possessed "the extraordinary intelligence, energy, and
self-discipline that enabled him to teach himself mathematics, engineering
theory, metallurgy, hydraulics, estimating, management, and everything
else a successful bridge designer had to know."
PROVIDING
A MUCH-NEEDED RAILROAD CONNECTION: In 1892, Oliver
W. Barnes, an engineer associated with Pennsylvania Railroad president
Alexander J. Cassatt and bridge designer Gustav Lindenthal, conceived
plans for the Hell Gate Bridge. Cassatt saw the Hell Gate project -
originally called the "East River Arch Bridge" - as an
opportunity to bring rail traffic from Pennsylvania Railroad routes in New
Jersey and points west through New York City to New England. The project
was to also tie into the Long Island Rail Road routes, in which the
Pennsylvania Railroad had a controlling interest. Meanwhile, Lindenthal
saw the Hell Gate project as his chance to construct his Hudson River
Bridge, a suspension bridge with a 2,800-foot-long main span that would
have been the longest in the world. That same year, the New York
Connecting Railroad was incorporated to help realize this plan.
In 1904, Lindenthal, who oversaw the opening of the Williamsburg Bridge
and the construction of the ongoing Manhattan Bridge and Queensboro Bridge
projects, was chosen as consulting engineer and bridge architect by the
Pennsylvania Railroad, which had just acquired the New York Connecting
Railroad. Under these auspices, Lindenthal was engaged in a project to
connect the tracks of the Pennsylvania Railroad in New Jersey, the Long
Island Rail Road in Queens, and the New York, New Haven and Hartford
Railroad in the Bronx. Although the project allowed Lindenthal to design
the Hell Gate span, it would not include his long-sought goal: a great
suspension bridge across the Hudson River. Instead, the Pennsylvania
Railroad decided to use exclusive tunnels for rail traffic across the
Hudson and East rivers.
DECIDING UPON A DESIGN:
The entire project, a 3.2-mile-long railroad bridge from Astoria, Queens
to the South Bronx, was comprised of the following sections:
Highlighting this project was the
Hell Gate span crossing the Hell Gate (roughly translated as
"beautiful strait" in Dutch), a portion of the East River with
treacherous currents separating Queens from Ward's Island, an island
that was used for a large state mental hospital. The steel-arch span,
which measures 1,017 feet, six inches long, was the longest span of its
type in the world when it opened. The four concrete towers that serve as
portals to the arch bridge are 250 feet high.
An inverted bowstring truss
bridge over Little Hell Gate connects Ward's Island with Randall's
Island, the former site of a correctional facility. This section
comprises of four 300-foot-long spans with reverse arches, each
separated by arched concrete piers. The four concrete towers that serve
as portals to the bowstring truss bridge are 155 feet high. (The Little
Hell Gate has since been completely filled in by parkland.)
A 350-foot-long fixed truss span
crosses the Bronx Kills. This section was originally planned as a
bascule bridge with 175-foot leaves. (Much of the Bronx Kills was filled
in subsequent years by parkland.)
The viaduct sections are
supported by arched concrete supports. From end to end, the bridge
measures 16,900 feet long.
Prior to the selection of the current design, three competing designs for
a bridge with an 850-foot main span over the Hell Gate were considered: a
stiffened suspension bridge with eyebar chains, a three-span continuous
truss bridge, and a three-span cantilever bridge. None of these
alternatives were selected, not only because of the concerns posed by the
dynamic loading of heavy railroad trains, but also because of the tight
curve that was necessary to avoid the state hospital buildings on Ward's
Island.
The approved design provided the high clearance required for navigation
across the Hell Gate, but did not require the long, straight approaches of
the other alternatives. Although its foundations would be more costly, the
steel arch design was cost-competitive because it required less steel than
the other alternatives.
CONSTRUCTING THE HELL
GATE COMPLEX: Lindenthal employed a staff of 95
engineers to calculate how the weight of the trains would be borne by
various parts of the bridge, how individual steel members would be made
and joined, how much masonry would be required, and how the different
functions of bridge construction (for example, the location of bridge
abutments vis-à-vis the alignment of the steelwork) would be coordinated.
With other engineers performing the calculations, Lindenthal concentrated
on the aesthetics of the bridge.
Lindenthal also appointed Othmar Ammann, who would later achieve fame in
building twentieth-century suspension bridges such as the George
Washington and Verrazano-Narrows bridges, as assistant chief engineer.
Ammann explained the significance that his mentor placed on the visual
appearance of his bridge:
Mr. Lindenthal conceived the bridge
as a monumental portal for the steamers that enter New York Harbor from
Long Island Sound. He also realized that this bridge, forming a
conspicuous object that can be seen from both shores of the river and from
almost every elevated point of the city, and will be observed daily by
thousands of passengers, should be an impressive structure. The arch,
flanked by massive masonry towers, was most favorably adapted to that
purpose.
A great bridge in a great city, although primarily utilitarian in its
purpose, should nevertheless be a work of art to which science lends its
aid. An elaborate stress sheet, worked out on a purely economic and
scientific basis, does not make a great bridge. It is only with a broad
sense for beauty and harmony, coupled with wide experience in the
scientific and technical field, that a monumental bridge can be created.
Fortunately, the Hell Gate Bridge was evolved under such conditions, and
therefore may be said to be one of the finest creations of engineering art
of great size that this century has produced.
By 1905, two competing steel arch designs were evaluated for the Hell Gate
span. The first design, a "crescent arch" where the upper and
lower chords of the arch meet at the anchorages of the bridge, copied the
design of Alexandre-Gustave Eiffel's Garabit Viaduct in France. This
design was assailed because it appeared weak in comparison to the great
height at the center of the arch. Another design, a flatter "spandrel
arch," had the lower chord begin at the bottom of the anchorages,
while the upper chord began at the top of the anchorages. The latter
design, which was inspired by similarly designed bridges over the Rhine
River in Germany, appeared more rigid, and was ultimately chosen for the
Hell Gate Bridge.
The Hell Gate Bridge used more steel than the Manhattan and Queensboro
bridges combined. The chords were made of a recently developed material -
carbon steel - that gave greater strength for its weight. The heaviest
bottom chord sections weighed 185 tons. All of this steel was necessary to
handle the heavy rail traffic of the day: the bridge was capable of
carrying 60 locomotives at a single time.
Lindenthal also played a role in the design of the tower piers, the
caissons for which had to be sunk to a depth of 90 feet to reach solid
rock. He adopted the initial tower design submitted in 1906 by consulting
architect Henry Hornbostel, but with modifications. The original design
left a gap of 15 feet between the beginning of the steel arch and the
masonry towers. Fearing that the public assumed that the towers support
the bridge, Lindenthal added girders between the upper chord of the arch
and the towers so that they would appear connected. The girders did not
have any engineering significance, but they added to the architectural
beauty of the bridge.
Construction of the Hell Gate project began in 1912, two years after the
first trains traveled under the Hudson River tunnels to Pennsylvania
Station in Manhattan. With construction well underway by 1914, another
change was made, this time to the viaducts leading to the Hell Gate span.
The original 1907 plan called for steel girders and steel piers to be
used, since Lindenthal believed that locally soft ground conditions, and
the underground network of sewers and utility lines would not support an
all-concrete viaduct. Concerns that inmates at the state institutions on
Ward's and Randall's islands would climb the steel piers for their escape
forced Lindenthal to use concrete for the viaduct piers instead. The steel
girders would be kept, but to deaden of sound of passing trains, the rails
would be embedded by 14 inches of broken-stone ballast, encased in
concrete.
Toward the end of 1915, the two trajectories of the steel arches from the
Astoria and Ward's Island anchorages met high above the Hell Gate. The
arch bridge, the two smaller bridges and the viaduct were completed in
September 1916. By 1917, the first Pennsylvania Railroad train - the
Federal Express service between Washington and Boston - went over the Hell
Gate Bridge, completing the first uninterrupted rail service between the
two cities.
When it opened in 1916, the Hell
Gate Bridge was the longest steel-arch bridge in the world. It held that
title until the Bayonne Bridge opened in 1931.
DOUBLE-DECKING THE HELL GATE?
In the 1920's, when the City of New York proposed the Triborough Bridge to
connect Manhattan, Queens and the Bronx, Lindenthal, who did not want to
spoil the view of his Hell Gate Bridge, devised an alternative design.
Instead of constructing what he called a "suspension bridge of cheap
pole and washline architecture," Lindenthal suggested adding a second
deck to his Hell Gate railroad bridge to carry five lanes of automobile
traffic. The alternative plan also called for two spurs: one to East 102nd
Street to provide direct access to Central Park, and another at East 116th
Street. While he did not immediately call for a spur at East 125th Street
- he believed that the area was already too congested - one was planned
for construction at a later date.
THE HELL GATE BRIDGE TODAY:
The Hell Gate Bridge, which today has the 17th longest main steel arch
span in the world, continues to play a central role in rail transportation
in the Northeast. Only three of the four tracks are used on the bridge.
The two south tracks carry Amtrak Northeast Corridor trains, while the
north inner track carries CSX and Norfolk Southern (the owners of the
former Conrail routes) freight trains. The north outer track is no longer
in operation.
In the late 1980's and early 1990's, Senator Daniel Patrick Moynihan, who
spent his childhood near the bridge in Astoria, lobbied to have the Hell
Gate Bridge refurbished. While the nearby Triborough Bridge was constantly
being maintained and repainted, the Hell Gate Bridge had not been painted
since it opened in 1916, except by the skillful hands of graffiti artists.
Since the bridge was deemed structurally sound by Amtrak president W.
Graham Claytor, Jr., he saw little need for spending money for
"cosmetic purposes." Buttressed by a 1991 article in The New
Yorker on what Moynihan called "a great engineering
miracle," Congress appropriated $55 million to repair and refurbish
the Hell Gate Bridge. A unique color was even selected for the bridge
paint: "Hell Gate Red." The refurbishing project was completed
in the 1996.
 |