President Coolidge stretched forth his arm to touch the golden lever of the presidential telegraphic instrument. He pressed, and a current of electricity flowed to Manhattan and directly across the Hudson river to Jersey City. At each place, in sight of thousands of crowding spectators, the current caused a pair of great U. S. flags slowly to separate. The Holland Vehicular Tunnel officially became open for inspection.
The spectators propelled themselves as speedily as possible into its white tiled maw. Seven hours later, at one minute after midnight, the motor vehicles for which the tunnel was built began to pass through from the New York and the New Jersey sides. In the second motor car to pay its toll fee*was Mrs. Clifford Milburn Holland, whose husband died as chief engineer of the tunnel. With her was Mrs. Milton H. Freeman, whose husband also died as chief engineer.
The Tunnel. The Holland Vehicular Tunnel consists of two tubes made of cast iron rings 29 ft. 6 in. in external diameter and lined with concrete. Other statistics:
Length† ....................................................9.250 ft.
Distance between portals ...................... 8,463 ft.
Length under river ...................... 5,480 ft.
Number of roadways ........................................ 2
Roadway width ..........................................20ft
Headroom ..........................................13½ft
Hourly vehicle capacity ..................................... 3,800
Maximum daily capacity ................................... 46,000
Yearly capacity .................................................. 15,000,000
Excavation ................................................... 500,000 cu. yd.
Cost .................................................................... $48,400,000
The Holland Tunnel's greatest problem was not its construction, but its ventilation—how to avoid the poisonous carbon monoxide gas exhausted from motor trucks and cars. Ventilation experiments at Yale, the University of Illinois and the U. S. Bureau of Mines showed that more than four parts of the gas in 10,000 of air was dangerous. 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. Fire hazard is prevented by watchmen stationed every few score feet; and there are tunnel fire engines at each entrance.
The Builder. The states of New York and New Jersey named the tunnel after Clifford Milburn Holland. In 1906, when he was 23, he left Harvard with both A. B. and B. S. degrees. At once he went to Manhattan, saying: "I am going into tunnel work and I am going to put a lot more into it than I'll ever be paid for." In his early 30's he was building simultaneously four street railway tunnels under the East River, between Manhattan and Brooklyn.