Qamchiq Tunnel
The 35th longest tunnel in the world
The Kamchiq Tunnel (Uzbek: Qamchiq tonneli) is a 19.2 kilometres (11.9 mi) long railway tunnel in Uzbekistan, which makes it the longest tunnel in Central Asia and in ex-USSR, and the longest broad gauge railway tunnel in the world (not counting metros).
Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).