Cosmic irony is a sharp incongruity between our expectations of things and what actually occurs, as if the universe were mocking us.
tragic irony occurs when a character onstage is ignorant, but the audience watching knows his or her eventual fate
Same article.

In this instance it was irony that the very thing that would have saved her life was denied her. This isn't like being in a wheelchair in a flood. This is a clear and specific link between her ability to hear and the very loud of the train. The incongruity occurs in that she is "miss" deaf texas. One would assume that she might have developed other abilities over the course of her life, like an acute situational awareness. Would you not expect her to look both ways? Clearly, this did not occur, and her lack of hearing then effected her death.

It is sad. And Ironic.