In October 1920, General George R. Dyer, the chairman of the New York Tunnel Commission, published a report in which he wrote that Singstad had devised a feasible ventilation system for the Hudson River Tunnel. Working with Yale University, the University of Illinois, and the United States Bureau of Mines, Singstad built a test tunnel in the bureau's experimental mine at Bruceton, Pennsylvania, measuring over long, where cars were lined up with engines running. Volunteer students were supervised as they breathed the exhaust in order to confirm air flows and tolerable carbon monoxide levels by simulating different traffic conditions, including backups. The University of Illinois, which had hired the only professors of ventilation in the United States, built an experimental ventilation duct at its Urbana campus to test air flows. In October 1921, Singstad concluded that a conventional, longitudinal ventilation system would have to be pressurized to an air flow rate of along the tunnel. On the other hand, the tunnel could be adequately ventilated transversely if the compartment carrying the tube's roadway was placed in between two plenums. A lower plenum below the roadway floor could supply fresh air, and an upper plenum above the ceiling could exhaust fumes at regular intervals.
In October 1920, General George R. Dyer, the chairman of the New York Tunnel Commission, published a report in which he wrote that Singstad had devised a feasible ventilation system for the Hudson River Tunnel. Working with Yale University, the University of Illinois and the United States Bureau of Mines, Singstad built a test tunnel in the bureau's experimenta,l mine at Bruceton, Pennsylvania, measuring over long, where cars were lined up with engines running. Volunteer students were supervised as they breathed the exhaust in order to confirm air flows and tolerable carbon monoxide levels by simulating different traffic conditions, including backups. The University of Illinois, which had hired the only professors of ventilation in the United States, built an experimental ventilation duct at its Urbana campus to test air flows. In October 1921, Singstad concluded that a conventional, longitudinal ventilation system would have to be pressurized to an air flow rate of along the tunnel. On the other hand the tunnel could be adequately ventilated transversely if the compartment carrying the tube's roadway was placed in between two plenums. A lower plenum below the roadway floor could ,supply fresh air, and an upper plenum above the ceiling could exhaust fumes at regular intervals.