* The two paths the characters can take: The story centers around a crucial decision the couple must make: whether or not to have an abortion. The two lines of rails can symbolize the two possible paths their lives could take, one leading to a future with the child and the other to a life without it.
* The diverging perspectives of the man and woman: The man clearly wants the woman to have the abortion, while the woman is hesitant and uncertain. The rails could represent their opposing viewpoints and desires, emphasizing the communication breakdown and the lack of shared understanding between them.
* The inevitability of choice: No matter which direction the train travels, it will still move forward. This could symbolize the inevitable nature of their decision, regardless of their feelings or opinions.
* The feeling of being trapped: The rails represent a confined space, much like the couple's relationship feels. They are both trapped in a situation they don't want to be in, with limited options and choices.
* The journey towards an uncertain future: The train journey itself is a metaphor for their life together. It's heading towards an unknown destination, full of potential challenges and unknowns, mirroring the uncertainty surrounding their decision and their future as a couple.
It's important to note that the story is open to interpretation and these are just a few possible meanings. The beauty of Ernest Hemingway's writing lies in its ambiguity, allowing readers to draw their own conclusions and find personal meaning in the story.