Originally Posted by sarflonlad
These are the words of a man who has never traveled on LU!
It reaches way in to the 40s+ in temperature during the summer months on LU. The humidity is also insanely high!
I travelled LU several times. But keep in mind how old the tube is. Building standards were different back then. Also the tube has many very small and narrow tunnels and small stairways which limits airflow. Most modern systems are not a/ced (I'm talking about the stations not the trains), yet are built so there is a constant exchange of air, either naturally (through the architecture) or artifcially.
edit: If I'm correct most LU trains are not a/ced. And that's where heat is usually the biggest problem.