"1969-12-08Z"^^ . "American civil engineer" . "1882-06-29Z"^^ . . "Ole Singstad"@en . . . "Singstad, Ole"@en . . . . "Ole Knutsen Singstad (June 29, 1882 \u2013 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.By 1950, Singstad had designed and overseen the construction of more underwater tunnels than all other engineers combined."@en . . "Ole Knutsen Singstad"@en . . "1882Z"^^ . . . "1969Z"^^ . .