What tunnel runs under the Hudson River and has a ventilation system innovated by Ole Knutsen Singstad?
Holland Tunnel The Holland Tunnel is a highway tunnel under the Hudson River between Manhattan in New York City and Jersey City, New Jersey. Its two tubes carry eastbound and westbound Interstate 78. In New Jersey, it is also designated NJ 139. An integral conduit within the New York Metropolitan Area, it opened in 1927 as the first of two vehicular tunnels under the river, the other being the Lincoln Tunnel. Both are operated by the Port Authority of New York and New Jersey.
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.