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.
Johanneshovsbron Johanneshovsbron (Swedish: "The Johanneshov Bridge") is a 756 metres long and 17,9 metres wide road bridge in central Stockholm, Sweden. Overpassing two older bridges, Skansbron and Skanstullsbron, and one newer bridge, Fredriksdalsbron, it connects Södermalm and the tunnel passing under it, Söderledstunneln, to Johanneshov, the district immediately south of the historical city centre, and national road 73, leading out of the city.