This 2002 photo shows the Manhattan Bridge from the northbound FDR Drive in Manhattan. (Photos by Jim K. Georges.)
PLANNING "SUSPENSION BRIDGE NUMBER 3": The Manhattan Bridge was first planned as a traditional wire-cable suspension bridge to be used exclusively by trains. In 1892, elevated railway magnate Frederick Uhlmann proposed this span just north of the present site of the Manhattan Bridge. The bridge was planned in conjunction with another one of his proposals, the Williamsburg Bridge. While Uhlmann's railroad bridge was never constructed, the Williamsburg Bridge was approved in 1895 to handle mixed traffic.
In 1901, Gustav Lindenthal, the commissioner of the newly created New York City Department of Bridges, presented plans for the proposed Manhattan Bridge (originally called "Suspension Bridge Number 3"), which was to connect the Bowery and Canal Street in Chinatown with Flatbush Avenue in downtown Brooklyn. He selected R.S. Buck as the chief engineer of the project. While he was no relation to Leffert L. Buck, the chief engineer on the Williamsburg Bridge project, R.S. Buck worked with him as an assistant on other projects. The project, which had the support of Mayor Seth Low, got underway on October 1, 1901.
Lindenthal's first proposal called for a hybrid design that featured design elements from the Brooklyn and Williamsburg bridges. Like the Williamsburg Bridge, the proposed bridge was to have massive steel towers and deep stiffening trusses (at 55 feet, they were to be even deeper than the 40-foot truss of the Williamsburg Bridge). The towers were to be crowned by minaret-like ornaments. Like the Brooklyn Bridge, the proposed bridge was to have both vertical suspender ropes and diagonal cable stays. The influential Municipal Art Commission rejected the proposal.
Two years later, Lindenthal proposed a second design that was radically different than any previously seen in American bridge design. Instead of employing a traditional wire-cable suspension design, he designed a suspension system where the suspenders were connected to steel eyebar chains by pin connections. Instead of being woven from steel wires, the cables would consist of four chains of nickel-steel eyebars, which would be stiffened and braced. Together with the suspenders, the eyebar chains that connected the towers with the anchorages would help support the deck. The deck was different also because there would be no deep stiffening trusses as there were in the deck of the Williamsburg and Brooklyn bridges. Instead, the stiffening system - the first application of Warren stiffening trusses on a suspension bridge - was incorporated into the cables.
The revised design also featured radically different towers. Unlike the rigid, three-dimensional tower profiles of the Brooklyn and Williamsburg bridges, the Manhattan Bridge, which features four columns in each tower, was to have a two-dimensional tower profile. The less rigid design allowed for greater flexibility, expansion and contraction of both the tower and the cables, which rest on ornamental saddles atop the towers. The flexible tower design was the first such application for a suspension bridge.
Serious questions were raised about Lindenthal's revised eyebar suspension design. George W. Calles, a Canadian engineer writing in Engineering News, opined that "a chain-bridge is a very ugly thing, excusable only on the grounds of engineering expediency." More seriously, Calles raised concerns that it would not be easy to inspect and maintain the tight connections between the eyebars and the suspenders. He said that potential cracks could grow to dangerous proportions, threatening the integrity of the structure.
The battle over Lindenthal's eyebar design and a more conventional design continued through 1904. However, it may have been politics - not engineering - that eventually killed the Lindenthal design. The new mayor, George McClellan, and the Roebling Wire Works (which had an interest in building a traditional wire-cable design) had political and financial links to Tammany Hall. With a new mayor in office, Lindenthal was ousted as bridge commissioner.
Original cross-section of the roadway on the Manhattan Bridge. (Figure by Paul Phillipe Cret and Rudolphe Modjeski.)
NEW MANAGEMENT, NEW DESIGN: McClellan's new bridge commissioner, George E. Best, appointed a new chief engineer, Othniel Foster Nichols, to oversee construction of the Manhattan Bridge. Nichols selected a design based on a new theory - deflection theory - that was developed by Leon Moisseiff, a design engineer with the Bridge Department.
Deflection theory stated that the following three opposing forces act on the deck and suspension cables:
one downward force caused by the load of the roadway one force in one part of the cable, pulling up and to the left one force in the other part of the cable, pulling up and to the right
According to deflection theory, suspension bridges are stronger than they at first were considered, because the curve of in the cables makes them more efficient in carrying loads than stiffer types of bridges, allowing bridges to require less material.
Rudolph Modjeski, who worked as chief engineer on a wide variety of bridges across the country, cooperated with Nichols and Moisseiff to oversee construction of the Manhattan Bridge. This oversight came to the fore in wake of the 1907 collapse of the Quebec Bridge.
The two-dimensional towers were among the few surviving features from the Lindenthal's second design. However, the 322-foot-tall towers support four main wire-spun cables, each measuring 3,224 feet long, in a more traditional suspension design. The 21¼-inch-diameter main cables were the largest suspension cables employed in bridge design at the time. Together, the four cables support two decks: the lower deck originally carrying four vehicular lanes (two lanes in each direction), flanked by subway tracks on each side, and the upper deck originally carrying streetcar lines situated above the subway tracks. The upper and lower decks are carried within a 26-foot-deep stiffening truss, half the depth of the Lindenthal design.
Other Lindenthal design touches were maintained at the approaches to the bridge. Carrere and Hastings, the architect team who designed the New York Public Library lent their talents to Lindenthal for their design of the anchorages and Manhattan approach. The two granite-encased anchorages contain arches, buttresses and other architectural embellishments. A Baroque arch modeled after Porte St. Denis, a gateway to Paris, frames the Manhattan entrance to the bridge.
Even as construction progressed under Nichols, Modjeski and Moisseiff, Lindenthal maintained his grudge against McClellan and Tammany Hall. He criticized that bridges constructed under Tammany administrations were characterized by long delays, blown budgets and political corruption. Eager to portray himself as a reformer, and to prove Lindenthal's charges wrong, McClellan rushed work on the Manhattan Bridge. The four main cables were spun over the East River in a record four months time during 1908.
On December 31, 1909, in what he earlier promised to be his last act in office, McClellan formally opened the $31 million Manhattan Bridge. When the bridge opened, the four trolley tracks, four subway tracks and pedestrian walkway had not yet been completed because a new city administration had removed mass transit from the control of the bridge commissioner. In his final technical report, Modjeski gave the new span "a clean bill of health."
This 1933 photo shows the Manhattan Bridge, looking south along South Street in lower Manhattan toward the Financial District. (Photo by Library of Congress, Prints and Photographs Division, Gottscho-Schleisner Collection, LC-G612-19733.)
"One of the problems with extending rehabilitation work on a bridge this old is that deterioration accelerates. You end up spending extra time and money doing emergency repairs on things you plan to replace anyway." - Herbert Rothman, Weidlinger Associates
SUBWAY TRAFFIC TAKES ITS TOLL: As applied on the Manhattan Bridge, deflection theory allowed for economies of material, cost and time. However, the theory did not take into account the problem of the subway trains on the outer parts of the lower deck. Over the years, heavy subway traffic caused considerable twisting of the deck. Maximum torsion occurs when subway trains start to cross opposite sides of the bridge at the same time. At that moment, one side of the roadway dips four feet to the north side, while the other side of the roadway dips four feet to the south side, creating a total roadway deflection of up to eight feet.
During the 1940's, the two decks of the Manhattan Bridge were reconfigured to carry seven lanes of vehicular traffic and four subway tracks. Three additional vehicular lanes were created on the center lower level, where four trolley lines previously ran.
Even at this early date, the bridge showed signs of strain. The stringers of the upper roadways had to be replaced, and the bracing failed frequently despite numerous additions. Slipping and chafing also occurred where the suspender cables met the main cables and the stiffening trusses. Famed bridge designer David Steinman argued that the best way to save the bridge was to remove the subways and build a separate tunnel for them.
THE LONG ROAD OF RECONSTRUCTION: In 1978, engineers inspecting the Manhattan Bridge found cracking and corrosion. Further investigation determined that the cracking originated from one-sided trainloads on the outboard structures. Even the passage of a single train caused microscopic cracks to develop, and over the course of decades, larger cracks developed. To make matters worse, corrosion was found in the eyebars anchoring one of the four suspension cables, forcing an emergency closure of the bridge.
After briefly considering plans to build a replacement bridge, the New York City Department of Transportation (NYCDOT) decided to rebuild the existing Manhattan Bridge in 1982. Work on the bridge was to be carried out under three separate contracts, the first two for stiffening the side and main spans, followed by a third one for the installation of prefabricated panels on the lower roadway.
The fate of the Manhattan Bridge is linked to that of the other East River bridges - the Queensboro, Williamsburg, and Brooklyn Bridge - and shares funds with the other bridges as mandated in the multi-billion dollar Federal Bridge Replacement Act. Repair schedules among the four bridges are therefore linked, meaning that each bridge depends on the others to provide sufficient traffic lanes over the East River.
The long-term reconstruction project also included an overhaul of the outboard structures that carry the four subway tracks. The westbound tracks were closed between 1985 and 1988, while the eastbound tracks were closed between 1988 and 2004.
The following timeline shows the Manhattan Bridge reconstruction schedule:
The first contract, a $40 million reconstruction of the side spans, was awarded originally to American Bridge Company. After the American Bridge Company decided to diversify away from bridge contracting work, another contractor resumed work. When the new contractor took over, some of the substandard steel had to be replaced before work resumed. In 1992, the second phase of the reconstruction project began on the suspended side spans. This contract was awarded at $97 million.
The next phase of reconstruction, a $350 million project to stiffen the main span, add new expansion joints, and reconstruct the upper roadways, began in 1995. To remedy the twisting of the superstructure caused by passing trains, the contractors installed end frames to the bridge. Theses frames couple the Warren stiffening trusses to the towers. This work, which was overseen by Weidlinger Associates, incorporated a revised design that complies with new seismic codes in New York City. This phase, which required the suspension of subway service and periodic closure of the upper roadways, was completed in 2004. Upon completion of this phase, full subway service for 220,000 riders was restored on the four tracks that carry the B, D, and Q lines.
The next phase entailed the reconstruction of pedestrian and bicycle paths. The NYCDOT opened the path on the southern side of the bridge in 2001, and a second path on the northern side of the bridge in 2004. Pedestrians have use of the southern path, while cyclists have use of the northern path.
In October 2006, construction crews closed the three-lane lower roadway to remove and replace the deck. This final phase of the project is scheduled for completion in October 2007.
Upon full completion of the $646 million reconstruction project, the bridge will carry approximately 150,000 vehicles per day (AADT).
The long-delayed reconstruction drew criticism from the New York City Council. Kathryn Freed, chairwoman of the Contracts Committee in the City Council, plans to hold hearings to look into all construction contracts, and plans to subpoena NYCDOT officials. The hearings come after Nada Chakravartti, the chief engineer on the Manhattan Bridge project, was charged in March 2001 with soliciting a bribe from a contractor after a period of investigation by the Manhattan district attorney's office.
HOV RESTRICTIONS POST-9/11: For about one week after the September 11, 2001 terrorist attack on the World Trade Center, the Manhattan Bridge was closed to all traffic except emergency vehicles. When the bridge reopened, the New York City Department of Transportation (NYCDOT) imposed new HOV restrictions as part of larger-scale efforts to reduce congestion in Manhattan below 63rd Street. The Manhattan-bound HOV restriction applied during the morning rush until November 2003.
TOLLS WON'T COME TO THE MANHATTAN BRIDGE: In 2002, Mayor Michael Bloomberg sought to either transfer ownership or sell the Manhattan Bridge to MTA Bridges and Tunnels. According to one estimate, the Manhattan Bridge and the other toll-free East River Bridge under NYCDOT would bring in approximately $800 million in annual toll revenue. The tolls would most likely be collected electronically since there is limited space to construct new toll plazas, and congestion (peak-hour) tolls would likely be implemented. The transfer or sale would have required the approval of the City Council and the State Legislature. However, Governor George Pataki killed this plan.
THE MANHATTAN BRIDGE AND THE INTERSTATE SYSTEM: The Manhattan Bridge carried NY 27 shields from the 1930's until 1972. Today, the bridge carries no numerical route designation.
In 1958, the Manhattan Bridge was planned to have been part of Interstate 478. The early incarnation of I-478, whose designation was originally I-178 until it was determined that the spur actually connected two Interstate highways, was to link the unbuilt Lower Manhattan Expressway (I-78) with the Brooklyn-Queens Expressway (I-278). The Lower Manhattan Expressway proposal was killed in 1971, shifting the I-478 designation to Westway, another Manhattan highway proposal that eventually was killed.
LEFT: This 1996 photo shows the Manhattan Bridge looking toward Manhattan. On its roadway, the bridge carries seven lanes of traffic and four subway tracks between lower Manhattan and Brooklyn. RIGHT: From this 1996 photo atop the Manhattan Bridge, one can see the decorative spheres of the bridge towers and the lower Manhattan skyline. (Photos by Dave Frieder, www.davefrieder.com.)
To maintain the structural integrity of the Manhattan Bridge, the subway tracks should be removed. New subway tunnels should be constructed alongside the existing IND subway tunnel between Rutgers Street in Manhattan and Jay Street in Brooklyn.
Type of bridge: Construction started: Opened to traffic: Length of main span: Length of side spans: Length, anchorage to anchorage: Total length of bridge and approaches: Number of decks: Number of traffic lanes: Number of subway tracks: Height of towers above mean high water: Clearance at center above mean high water: Number of cables: Diameter of each of four cables: Length of each of four cables: Structural material: Tower material: Deck material: Cost of original structure:
SOURCES: Joint Study of Arterial Facilities, The Port of New York Authority and the Triborough Bridge and Tunnel Authority (1955); The Bridges of New York by Sharon Reier, Quadrant Press (1977); "Free Bridges Taking a Toll" by Molly Gordy, Newsday (5/06/1988); Great American Bridges and Dams by Donald C. Jackson, Preservation Press-John Wiley and Sons (1988); "Manhattan Bridge Shut for Repairs" by Molly Gordy, Newsday (2/01/1989); Engineers of Dreams by Henry Petroski, Vintage Books-Random House (1995); "The Manhattan Bridge Story," Weidlinger Associates (1996); "A Guide to Civil Engineering Projects in and Around New York City," American Society of Civil Engineers (1997); Bridges by Judith Dupre, Black Dog And Leventhal Publishers (1997); "Engineer Tracks Bridges' Twists and Turns" by Robin Finn, The New York Times (12/15/2000); "Bridge Fix from Hell" by J.K. Dineen, New York Daily News (4/25/2001); "Mayor Weighs Plan To Turn Over Bridges to Transit Authority" by Jennifer Steinhauer, The New York Times (10/22/2002); "Subway Bridge Where the Rust Is Finally History," New York Daily News (2/22/2004); New York City Department of Transportation; Transportation Alternatives; Hank Eisenstein; Dave Frieder; Ralph Herman; Christof Spieler; Stephen Summers; Kevin Walsh.
NY 27 and I-478 shields by Ralph Herman. Lightposts by Jeff Saltzman. HOV sign by C.C. Slater.