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.
Lopper II Rail Tunnel The Lopper II Rail Tunnel is a railway tunnel in the canton of Nidwalden in central Switzerland. It forms part of the Zentralbahn Luzern–Stans–Engelberg line, which links Lucerne with Engelberg, between Hergiswil station and Stansstad station. It is 1743 m in length, and carries metre gauge () track electrified at 11 kV AC 16 2/3 Hz using overhead catenary. The tunnel runs under the Lopper, a shoulder of Mount Pilatus which extends into Lake Lucerne, and immediately on leaving the tunnel the line crosses a bridge over the Alpnachersee arm of Lake Lucerne before entering Stansstad station.