The story plays with the idea of the supernatural. The apparitions that the signalman sees could be a product of his overworked and stressed mind, or they could be real ghosts. Dickens uses this ambiguity to great effect, keeping the reader in suspense. For example, the way the figure always appears before a tragic event on the railway line is very spooky.
The use of foreshadowing in 'The Signalman: A Ghost Story' is masterful. The repeated warnings from the apparition and the signalman's growing dread all lead up to the final tragic event. It also explores themes of fate and the inability to escape a pre - determined course of events. The gloomy and often claustrophobic descriptions of the signalman's workplace add to the overall sense of doom in the story.