The Robert F. Kennedy Bridge (RFK Bridge; or more commonly referred to by locals by its name prior to 2008, the Triborough Bridge, or Triboro) is a complex of bridges and elevated expressway viaducts in New York City. The bridges link the boroughs of Manhattan, Queens, and the Bronx. The viaducts cross Randalls and Wards Islands, previously two islands and now joined by landfill.
The RFK Bridge, a toll bridge, carries Interstate 278 (I-278) as well as the unsigned highway New York State Route 900G. It connects with the FDR Drive and the Harlem River Drive in Manhattan, the Bruckner Expressway (I-278) and the Major Deegan Expressway (Interstate 87) in the Bronx, and the Grand Central Parkway (I-278) and Astoria Boulevard in Queens. The three primary bridges of the RFK Bridge complex are: The vertical-lift bridge over the Harlem River, the largest in the world, connecting Manhattan Island to Randalls Island (all within Manhattan) The truss bridge over Bronx Kill, connecting Randalls Island to the Bronx The suspension bridge over Hell Gate (a strait of the East River), connecting Wards Island to Astoria in Queens
These three bridges are connected by an elevated highway viaduct across Randalls and Wards Islands and of support roads. The viaduct includes a smaller span across the former site of Little Hell Gate, which separated Randalls and Wards Islands.See:
Also part of the complex is a grade-separated T-interchange on Randalls Island, which sorted out traffic in a way that ensured that drivers paid a toll at only one bank of tollbooths. The tollbooths have since been removed, and all tolls are collected electronically at the approaches to each bridge.
The bridge complex was designed by Allston Dana with the collaboration of Othmar Ammann and architect Aymar Embury II,Shanor, Rebecca Read. "Robert F. Kennedy Memorial Bridge [Triborough Bridge]" in and has been called "not a bridge so much as a traffic machine, the largest ever built". The American Society of Civil Engineers designated the Triborough Bridge Project as a National Historic Civil Engineering Landmark in 1986. The bridge, named for former New York senator Robert F. Kennedy, is owned and operated by MTA Bridges and Tunnels (formally the Triborough Bridge and Tunnel Authority, or TBTA), an affiliate of the Metropolitan Transportation Authority.
Description The RFK Bridge is made of four segments. The three primary spans traverse the East River to Queens; the Harlem River to Manhattan; and Bronx Kill to the Bronx, while the fourth is a T-shaped approach viaduct that leads to an interchange plaza between the three primary spans on Randalls Island. The Queens arm of the viaduct formerly crossed Little Hell Gate, a creek located between Randalls Island to the north and Wards Island to the south. Excluding elevated ramps, the segments are a total of long, with a span between the Bronx and Queens, and a span between Manhattan and the interchange plaza. In total, the bridge contains of roadway, including elevated ramps.
The bridge was primarily designed by chief engineer Allston Dana and architect Aymar Embury II. Wharton Green served as the Public Works Administration (PWA)'s resident engineer for the project.
East River suspension bridge (I-278)
The East River span, a suspension bridge across the Hell Gate of the East River, connects Queens with Wards Island. It carries eight lanes of Interstate 278, four in each direction, as well as a sidewalk on the northeastern side. The span connects to Grand Central Parkway, and indirectly to the Brooklyn–Queens Expressway (I-278), in Astoria, Queens. Originally it connected to the intersection of 25th Avenue and 31st Street; the former was later renamed Hoyt Avenue. The suspension span was designed by chief engineer Othmar Ammann. The span was originally designed to be double-decked, with eight lanes on each deck. When the construction of the Triborough Bridge was paused in 1932 due to lack of funding, the suspension span was downsized to a single deck. There are Warren trusses on each side of the span, which stiffen the deck.
The center span between the two suspension towers is long, and the side spans between the suspension towers and the anchorages are each long. The total length of the bridge is , and the deck is wide. The columns under the Wards Island approach roadway were originally placed atop 400,000 steel ball bearings, allowing the roadway to move sideways by up to in either direction.
At mean high water, the towers are tall, and there is of clearance under the middle of the main span. The suspension towers were originally designed by Arthur I. Perry. Each tower was supposed to have two ornate arches at the top, similar to the Brooklyn Bridge, and was to have been supported by four legs: two on the outside and two in the center. A 1932 article described that each tower would be made of 5,000 tons of material, including 3,680 tons of steel. The final design of the suspension towers, by Ammann, consists of comparatively simple cross bracing supported by two legs. The tops of each tower contain cast iron saddles in the Art Deco style, over which the bridge's main cables run. These are topped by decorative lanterns with red aircraft warning lights.
The span is supported by two main cables, which suspend the deck and are held up by the suspension towers. Each cable is in diameter and contains of individual wires. Each main cable is composed of 37 strands of 248 wires, for a total of 9,176 wires in each cable. The wires are fastened together by "strand shoes", placed at regular intervals. At the Wards Island and Astoria ends of the suspension span, there are two anchorages that hold the main cables. The anchorages contain a combined 133,500 tons of concrete. There are also bents atop each anchorage, which conceal the ends of each main cable.
Harlem River lift bridge (NY 900G)
The Harlem River span is a lift bridge that connects Manhattan with Randalls Island, designed by chief engineer Allston Dana. It carries six lanes of New York State Route 900G (NY 900G), an unsigned reference route, as well as two sidewalks, one on each side. The span connects to FDR Drive and Harlem River Drive, as well as the intersection of Second Avenue and East 125th Street, in East Harlem, Manhattan. At the time of its completion, the Harlem River lift bridge had the largest deck of any lift bridge in the world, with a surface area of . To lighten the deck, it was made of asphalt paved onto steel girders, rather than of concrete.
The movable span is long and wide. The side spans between the movable span and the approach viaducts are each long. The total length of the bridge is . The towers are above mean high water. Each of the lift towers is supported by two clusters of four columns, which supports the bridge deck. A curved truss at the top of each pair of column clusters forms an arch directly underneath the deck.
The lift span is above mean high water in the "closed" position, but can be raised to . The movable section is suspended by a total of 96 wire ropes, which are wrapped around pulleys with diameters. These pulleys, in turn, are powered by four motors that can operate at .
Exit list NY 900G is officially maintained as a north–south route, despite its largely east-west progression.
Bronx Kill crossing (I-278)
The Bronx Kill span is a truss bridge that connects the Bronx with Randalls Island. It carries eight lanes of I-278, as well as two sidewalks, one on each side. The span connects to Major Deegan Expressway (I-87) and the Bruckner Expressway (I-278) in Mott Haven, Bronx. It originally connected to the intersection of East 134th Street and Cypress Avenue, a site now occupied by the interchange between I-87 and I-278. The truss span was designed by consulting engineers Ash-Howard-Needles and Tammen.
The Bronx Kill span contains three main truss crossings, which are fixed spans because the Bronx Kill is not used by regular boat traffic. The main truss span across the Bronx Kill is long, while the approaches are a combined . The total length of the bridge is . The truss span is above mean high water.
Interchange plaza and approach viaducts
The three spans of the RFK Bridge intersect at a grade-separated T-interchange on Randalls Island. The span to Manhattan intersects perpendicularly with the I-278 viaduct between the Bronx and Queens spans. Although I-278 is signed as a west-east highway, the orientation of I-278 on the bridge is closer to a north-south alignment, with the southbound roadway carrying westbound traffic, and the northbound roadway carrying eastbound traffic. Two circular ramps carry traffic to and from eastbound I-278 and the RFK lift bridge to Manhattan. Randalls and Wards Islands are accessed via exits and entrances to and from westbound I-278; to and from the westbound lift bridge viaduct; to eastbound I-278; and from the eastbound lift bridge viaduct. Eastbound traffic on I-278 accesses the island by first exiting onto the lift bridge viaduct.
The interchange plaza originally contained two tollbooths: one for traffic traveling to and from Manhattan, and one for traffic traveling on I-278 between the Bronx and Queens. The tollbooths were arranged so vehicles only paid one toll upon entering Randalls and Wards Islands, and there was no charge to exit the island. The elevated toll plazas had a surface area of about and were supported by 1,700 columns, all hidden behind a concrete retaining wall. In 2017, the MTA started collecting all tolls electronically at the approaches to each bridge, and the tollbooths were removed from the toll plazas on the RFK Bridge and all other MTA Bridges and Tunnels crossings.
The Robert Moses Administration Building, a two-story Art Deco structure designed by Embury, served as the headquarters of the TBTA (now the MTA's Bridges and Tunnels division). The building was next to the Manhattan span's plaza, to which it was connected. In 1969, the Manhattan span's toll plaza was moved west and the I-278 toll plaza was moved south, and both toll plazas were expanded more than threefold. This required the destruction of the building's original towers. A room was built in 1966 to store Moses's models and blueprints of planned roads and crossings, but they were moved to the MTA's headquarters at 2 Broadway in the 1980s. The building was renamed after Moses in 1989.
The interchange plaza connects with the over-water spans via a three-legged concrete viaduct that has a total length of more than . The segments of the viaduct rest atop steel girders, which in turn are placed perpendicularly between concrete piers spaced apart. Each pier is supported by a set of three octagonal columns. The viaduct is mostly eight lanes wide, except at the former locations of the toll plazas, where it widens. The viaduct once traversed Little Hell Gate, a small creek that formerly separated Randalls Island to the north and Wards Island to the south; the waterway has since been filled in. The viaduct rose above the mean high water of Little Hell Gate.
Development Planning
Initial plans Edward A. Byrne, chief engineer of the New York City Department of Plant and Structures, first announced plans for connecting Manhattan, Queens and the Bronx in 1916. The next year, the Harlem Boards of Trade and Commerce and the Harlem Luncheon Association announced their support for such a bridge, which was proposed to cost $10 million. The "Tri-Borough Bridge", as it was called, would connect 125th Street in Manhattan, St. Ann's Avenue in the Bronx, and an as-yet-undetermined location in Queens. It would parallel the Hell Gate Bridge, a railroad bridge connecting Queens and the Bronx via Randalls and Wards Islands. Plans for the Tri-Borough Bridge were bolstered by the 1919 closure of a ferry between Yorkville in Manhattan and Astoria in Queens.