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Location: New York, New York, and Jersey City, New Jersey, USA
Completion Date: 1927
Cost: $48 million
Length: 8,558 feet (north tube), 8,371 feet (south tube)
Materials: Steel, concrete
Engineer(s): Clifford Holland
By the early 1920's, ferries across the Hudson River, the only mode of travel between New York City and New Jersey, strained to handle more than 20,000 vehicles a day. Fed up with the traffic congestion to and from the city, New York City officials decided to build an automobile tunnel under the Hudson River -- one that would double the daily traffic load across the river. The biggest challenge was ventilation. Without some way of eliminating all the poisonous carbon monoxide from the automobiles in the tunnel, most drivers would pass out before reaching the other side!
Engineer Clifford Holland came up with a brilliantly simple solution: big fans. Inside four massive ventilation buildings on both ends of the tunnel are 84 powerful electric fans that draw fresh air into the tunnel and blow dirty air out. Each fan is 80 feet in diameter. That's almost as tall as a 10-story building!
Unfortunately, fans this big can also be quite dangerous. In 1949, a chemical truck loaded with 80 drums of carbon disulfide exploded in the tunnel, injuring 69 people and causing $600,000 in damage to the structure. The ventilation buildings actually fanned the flames of the fire. As a result, strict standards were established in tunnels throughout the world for the transportation of chemicals and explosives.Here's how this tunnel stacks up against some of the longest tunnels in the world.
(total length, in feet)