Smoker

The engineers of the Holland vehicular tunnel, connecting Manhattan & New Jersey (TIME, Aug. 30), held a "smoker" last week. They exploded smoke bombs in the cavern they had built, far under the Hudson River, to produce a volume of fumes equivalent to that which would be caused if an automobile burned up on its way through one of the two tubes. Object: to test the ventilating system, upon which the whole success of the tubes depended. Result: complete success. The fumes did not spread more than 50 feet; were swept out of the tunnel in less than two minutes. . . . The problem of ventilating 9,250-foot tubes was more complicated than it would appear. Blowing fresh air in at one end and sucking it out at the other was pronounced impossible. It would take too long to clear the foul end in the event of a conflagration, and the percentage of carbon monoxide at the foul end would endanger life even under normal tunnel conditions. The late Clifford M. Holland won a mighty memorial by devising a system of four stations, operating 84 huge fans, to send currents of fresh air into the base of the tubes, on each side, through chutes running the length of the tubes with two-inch vents at close intervals. Outlet vents in the ceiling of the tubes draw the bad air out perpendicularly.