THIS is what a 'S' curve should look like. :) The lines lead to the primary subject and take the viewer thru the image. Hooray!
As for the image, I like the way the trees are forming a natural frame/tunnel for the train to come thru. Keeps the viewers focused and in a natural place as well (train is close to the upper ROT point).
Would be a tad stronger if the train was sharply focused instead of the tracks, but nonetheless I still like it overall. Good luck in the challenge.
I've tried to figure out what bothers me about this one. The angle is good, the track s shape is interesting. The smoke is nice ( although I'd like to see more of it ). I think the problem for me is that the photo seems slightly blurred. To me the photo should either be tack sharp or shot with a slow shutter speed to show motion in the train. This photo seems to be somewhere in between and just doesn't have impact in my opinion.