Faldage wrote The train was shown as traveling from the right side to the left side of the picture.

Presuming you mean right-to-left as I look at the picture :
East.


Surely, you need to know what time of day it is, so that you can note where the shadows fall. Or else look at the picture of the tree and see on which side the moss grows.


In any case, unless it is a moving picture, you do not have any idea whether the train is travelling forwards or backwards, which is a significant factor in solving this particular urgent problem.