Severomuysky Tunnel

node · earth · Severomuysky Range, Buryatia

At 15.3 km, the longest railway tunnel in Russia, carrying the Baikal–Amur Mainline under the Severomuysky Range in Buryatia. Driving it took roughly twenty-six years of intermittent work through faulted, water-bearing and partly frozen rock, and until it opened, BAM trains took a steep temporary bypass over the range that limited train weight and speed for the whole line. It is a clean demonstration of the ruling-gradient principle in reverse: the cost of the tunnel was justified entirely by what the bypass grade did to every train that used it.