While even the smallest subway stations are well lit structures built to impress just a few steps into the tunnels the subway becomes a dark and terrifying place. The tubes leading into either direction of the line are built closely together. And the small niches connecting them are usually the only places well lit. That is, if the single glow orb these niches contain is not broken. Besides this glow orb these niches contain another important bit of equipment, A rather grand switch box controlling not only power for the rails in either direction but also the signal lamps which are the only other illumination in the tunnels.
The walkways to either side of the tracks are narrow and whenever a train passes people venturing into the tunnels would be well advised to take shelter in one of the niches connecting the tunnels. Even in there the soft breeze continuously blowing through the tunnels will tear at the clothes of the unwary with hurricane strength as a train rushes past.