Nakayama Tunnel
The 56th longest tunnel in the world
Nakayama Tunnel (Nakayama tonneru) is a tunnel on JR East-Joetsu Shinkansen line in Japan that runs from Jomo Kogen, Takasaki city to Onoko, Shibukawa city, in Gunma prefecture with approximate length of 14.857 km. It was completed and opened in 1982.
Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).