The Signal-Man

Early in the story, the narrator refers to the train tunnel at the entrance to which the signalman works as "this great dungeon." In this metaphor, the narrator compares the empty, abyss-like tunnel to a fortified subterranean prison cell in order to convey the tunnel's nefarious qualities.

As the narrator listens to the signalman discuss his brushes with the specter, he "resist[s] the slow touch of a frozen finger tracing out [his] spine." In this metaphor, the narrator emphasizes the cold creeping sensation running down his back by describing it metaphorically as a frozen finger literally touching his skin.

The red light that hangs at the tunnel's entrance is both a literal signal of danger and a symbol for impending death. Whenever the signalman's telegraph bell rings without moving, he leaves his box and looks at the red danger light, because the specter always appears near the light. The danger of which the specter warns is always ambiguous to the signalman, but the specter's appearance near the light always presages death, ultimately predicting the signalman's own.