Sakanashi Tunnel
The Sakanashi Tunnel (Sakanashi Tonneru) is a tunnel on the border of Akita Prefecture and Aomori Prefecture on the Tōhoku Expressway. The tunnel crosses Sakanashi Pass of the northern Ōu Mountain Range. Its 4.27-kilometer-long (2.65 mi) northbound tunnel is the longest tunnel on the Tōhoku Expressway. Its completion in 1986 was one of the final pieces of the 679.5 km (422.2 mi) Tōhoku Expressway from Tokyo to Aomori.
Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).