What tunnel runs under the Hudson River and has a ventilation system innovated by Ole Knutsen Singstad?
Ole Singstad: Ole Knutsen Singstad (June 29, 1882 – December 8, 1969) was a Norwegian-American civil engineer who innovated the ventilation system for the Holland Tunnel (which subsequently became commonly used in other automotive tunnels) and advanced the use of the "Sunk-tube" method of underwater vehicular tunnel building, a system of constructing the tunnels with prefabricated sections. Holland Tunnel: The Holland Tunnel is a highway tunnel under the Hudson River between Manhattan in New York City and Jersey City, New Jersey.
Holland Tunnel