Final answer:
The atmospheric pressure pushing a person towards a moving train is due to the Bernoulli effect caused by the pressure gradient created by the train's motion.
Step-by-step explanation:
When a rapidly moving commuter train passes by, the air around the train is pushed outwards by the pressure gradient created by the train's motion. This reduces the atmospheric pressure close to the tracks, creating a region of lower pressure. As a result, the higher atmospheric pressure on the other side of the person pushes them towards the train. This phenomenon, known as the Bernoulli effect, explains why it is dangerous to stand close to railroad tracks when a rapidly moving train passes.