Monday 21st November 1927
Time magazine put the week-old Holland Tunnel on its cover. The tunnel, which runs under the Hudson River between New York City and Jersey City, New Jersey, had opened to traffic the week before, at the stroke of midnight on November 13. Time presented all of the tunnel’s vital statistics: its total length (9,250 feet, the “longest of its kind in the world”), length under the river (5,480 feet), hourly vehicle capacity (3,800), and cost ($48.4 million). It also explained the most significant thing about the tunnel: its sophisticated ventilation system. Until its engineers could figure out a way to keep carbon monoxide out of the air, building an underground road for cars and trucks had been a foolishly dangerous idea. As Time explained: “To prevent disaster absolutely Chief Engineer Holland installed 84 ventilating fans in four 10 story buildings, two on each side of the Hudson. Part of them blow fresh air into the tunnel floor through vents, others suck vitiated air through ducts in the tunnel ceiling. Thus they change the tunnel air completely 42 times an hour and but 56 of the fans are needed to do so.” The other 28 were reserved for emergency use. It took—and still takes—about 90 seconds to replace all of the air in the tunnel with fresh air.