on the arrival of a train in the station

I have read that because we read from left to right, the “natural” movement in a scene is from left to right. So, if it is something important, like the introduction of a major character or the arrival of a train, there is a tendency to observe this left-to-right movement. Right-to-left movement is said to be slightly disturbing, perhaps reserved for villains. For example, in the movie Shane (1953), the title character arrives from the left at the beginning of the movie, and moves toward the right when he leaves at the end. On the other hand, Wilson, the villain, enters from the right. But there are so many exceptions to this principle that I have my doubts as to how much it is observed.

As for trains in particular, the train in Once Upon a Time in the West (1968) enters from the left. So does the train in Bad Day at Black Rock (1955), which is almost a Western. The first time we see the train in Unforgiven (1992), it moves from left to right. But like you, I have seen plenty of trains moving from right to left, so despite what I have read, I don’t place much weight on this as a signifier.