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.
Cross-Harbour Tunnel The Cross-Harbour Tunnel (abbreviated "CHT" or "XHT") is the first tunnel in Hong Kong built underwater. It consists of two steel road tunnels each with two lanes constructed using the single shell immersed tube method.