lincoln tunnel construction

Lincoln tunnel construction: Sandhogs were built during the Great Depression. They had to go through rigorous physical testing to ensure that their hearts and lungs could withstand the lengthy compression and decompression chamber cycles necessary to construct a tunnel 10 stories deep. This was a deep-diving compression cycle that allowed Sandhogs only to work for half an hour each morning and half an hour at night.

The tunnel’s 31-foot outer lining was made up of hundreds of iron rings, each one weighing 21 tonnes. The tunnel was co-owned and funded by New Jersey and New York. One crew worked on the Jersey side, and another crew moved toward them from New York. This feat of engineering skill is remarkable in terms of alignment and depth.

Workers used a hydraulic shield ring to push the silt from the bore’s head in 36-inch increments. Then, they assembled and bolted the next inner ring in place. The two tunnel segments finally connected within a quarter inch. This was the moment when the first knock-through took place on August 3, 1935.

Engineers tried many ventilation systems before settling on one that consisted of 32 buildings. 15 of these buildings would draw in the fresh air, while 17 would blow out the dirty air.

On December 22, 1937, the world’s first mechanically-ventilated underwater tunnel would open to the world. In 1945, a second north tube was completed. This was delayed by material shortages during wartime. A third south tube was then opened in 1957.

Built at the cost of $240 million dollars, or roughly $4.5 billion in today’s currency, the one-and-a-half-mile-long tunnel network sees an average of 113,000 vehicles pass through its undersea network each and every day, making the Lincoln Tunnel one of the busiest passages in the world.