The first impression you get from this film shot in the tunnels of the New York subway over 100 years ago is an overwhelming sense of claustrophobia. The walls of the tunnels through which the trains travel are only inches wider than the carriages in some places, and anybody with a fear of confined spaces would no doubt be discouraged from going anywhere near the underground if they watched this.
As Snow Leopard has noted, it must have taken no small amount of resourcefulness on the part of Billy Bitzer to make this film. The lighting from the train that runs alongside the subject train casts an eerie glow that adds to the faintly unsettling atmosphere. The trains don't seem to travel very fast - although they might have been travelling slower than normal so that Bitzer could catch the action without too much jerking or vibration.