This is the inside of a M1 train, as seen between Sesto San Giovanni (FS) and Sesto Ronḍ. The M1 and M2 trains are practically identical, except that the M1 uses third rail for its passenger service but can use overhead wires for shunting as necessary.
There is still the occasional braking compressor noise in this series, and it can get quite hot even in a tunnel.
Copyright 2004 by Josh Hanz (josh_hanz@hotmail.com)