Symbolism, Imagery, Allegory
Strip Tease
The very first thing we see in Girl on the Train—seriously, we're talking about the very first line of the book—is "a pile of clothing on the side of the train tracks" (1.1), specifically a dirty t-shirt and one shoe. Since this is the first visual in a book that turns out to be a mystery, these clothes must be an important clue, right? Not so fast.
This pile of clothes is one of many moments of misdirection in this book. It also illustrates Rachel's overactive imagination, though. She tries to imagine how the clothes got there, and she thinks about how getting hit by a train can knock a person's clothes clean off. "It's not that unusual, death by train" (1.19), she says. And when she does, we find ourselves making a mental note that we might have some foreshadowing on our hands.
Alas, we do not. No one is hit by a train in this book, so all that's actually happened is a bit more misdirection. And this, of course, happens throughout the book until the very end. The pile of clothes, then, and the ensuing comment about "death by train" set the stage for a whole lot of other pieces of information that could be significant… but aren't.
However, a different pile of clothes later on (who keeps stripping near the train?) gets Rachel thinking. She sees a dark blue dress, and thinks, "It seems to me that I've seen that dress before, I've seen someone wearing it. I can't remember when" (25.36). She eventually remembers Megan getting into Tom's car that night. Although this dress probably isn't hers, it at least serves a purpose in jogging her memory. Kind of like how the opening pile of clothes reminds us once we finish reading that this book majorly messes with us along the way.