I went thru those tunnels in 1954 and 1958 as a kid on vacation. They had the old low-pressure sodium lights that made your skin look purple-green. Fun.
Marin County on the north end of the Golden Gate Bridge has an old military tunnel that carries traffic between Sausalito and the GG Natl. seashore park. One way traffic alternates in each direction each 5-10 minutes. Open to bicycles. The cars go in and you sprint for the other end after them. Dark and damp. If you are slow cars now going the other way have just enough room to pass you. E-maail if you ae in the area.