A screen shot of the work in progress.

A screen shot of the layers.

The track was selected, copy and pasted on a new layer and then warped into a curve to fit the train direction.
The train was selected from the photo and then a mask was added to clean up the edges. It was placed on top of the tracks.
Clock face was selected from the challenge copy and enlarged to fit around the train.
Another copy was reduced to fit the front of the train.
A copy of merged layers was blurred with a radial blur on zoom mode and blended on soft light mode to give a hint of movement to the background. Train was masked out and the mask was applied to the layer.
Clouds were added to the sky.
Colour was added to change the grass colour to more of a brown shade
I cut a hole from the bricks from the original challenge photo and cloned bricks over the original clock face.
Added a drop shadow to the brick wall.
Added smoke coming from train with cloud brushes and some flying rocks with rock brushes.
Copied a merged image onto a new layer and added an emboss effect on overlay mode to enhance the textures.
Used different blend modes for different layers, mostly multiply, overlay and soft light.
Merged the end result and then adjusted levels, colours and contrast.

The steps may not be in the correct order but it is a general idea of what I did in between having visitors and doing other things for the day.