How does Dickens use literary devices in "The Signal-Man"?

In "The Signal-Man," Dickens uses a number of literary devices to emphasise his key themes and to build suspense as the story develops. 

To illustrate this, look at how Dickens uses point of view. From the title, we might expect the story to be told from the signalman's perspective. But, in fact, the story is told from the perspective of a male visitor. Everything we learn about the signalman, we learn from this visitor's point of view. By doing this, Dickens transforms the signalman into a mysterious character, therefore building suspense as the story develops.

Similarly, Dickens uses language to heighten the signalman's sense of mystery. Imagery transforms his environment, the signal box, into a mysterious and other-worldly sort of place. This is created with words like "trench," "dungeon" and "gloomy." In this "oozier" and "wetter" place, the narrator feels as though he has left the "natural world," and this is very effective in creating a sense of mystery. 

In addition, Dickens uses foreshadowing to create suspense in the story. One of the best examples of this comes on the first page when the narrator says:

Just then there came a vague vibration in the earth and air, quickly changing into a violent pulsation, and an oncoming rush that caused me to start back, as though it had force to draw me down.

This may appear like nothing more than a description of a passing train but its position in the text suggests that something important and momentous is about to happen. As we later learn, this first meeting between the narrator and the signalman is indeed significant: it represents the beginning of the signalman's demise.