Tom Scott - Keeping the world's longest railroad tunnel safe, 10102022

Gotthard Base Tunnel is the longest & deepest rail tunnel in the world, 57km through the Alps. It's called a "base tunnel" because it's at the base of the mountain. At its deepest point, there are more than 2km of rock above. The earth in there is hot. Without ventilation, the air temperature will be more than 40°C Due to two devastating fires in road tunnels under these mountains, the Swiss authorities want to make sure that nothing like that ever happens again. How they do that is fascinating