Originally proposed in 1930, the tunnel was not funded until 1933. Work was undertaken from both sides concurrently which meant that the holes on both sides needed to match. In order to withstand the high air pressure needed to keep the water from seeping in, the ‘Sandhogs’ as the workers were known had to enter the tunnel through airlocks which would gradually increase the pressure as they descended from lock to lock. Because of the Depression and the War it took nearly a decade to build the first two tubes.
Opened, Dec 22, 1937
2nd Tube Opened, Feb 1, 1945
3rd Tube Opened, May 25, 1957
Exclusive Bus Lane Opened, Dec 18, 1970
Considered a traffic breakthrough at the time, the concept went on to get implemented widely.