This 1956 photo shows the massive inclined ramp, known as the Helix, that carries traffic to and from the Lincoln Tunnel on the New Jersey side of the Hudson River.
The related cover described the construction of the third tunnel tube, which required widening of the Helix and other changes to the approach roads. The Helix is designed to carry traffic 160 feet up from the tunnel mouth as it makes a 270° turn over King’s Bluff Ledge, known as the Palisades, and feeds it onto the New Jersey Turnpike.
The Helix is a complex structure, beginning as a concrete roadway on earth fill, changing to a heavy steel truss bridge, then to a curved trestle resting on circular piers, then to three large bridge trusses, then to a trestle resting on tall concrete legs until it meets the Palisades rock.
Construction of the 8,216-foot-long third pipe required the excavation of more than 500,000 m3 of soil and rock; use of 3,000 tons of steel in five extended bridges and viaducts; placement of 77,000 cubic meters of concrete and a maximum workforce of 700.
The combined annual traffic of the two existing tubes, completed in 1937 and 1945, had reached 21 million by 1955, prompting the owner, the Port Authority of New York and New Jersey, to build the third tube.
Currently the tunnel’s annual traffic volume is 43 million, making it the world’s largest vehicle tunnel.
