The one word which will probably make it much more clear is "cutting" - this is a noun (not the gerund of the verb 'cut').

It means a man-made valley cut into high land, through which a road or railway travels.



As the train passed, there was a glare of light above the cutting.
Also there was a driving tumult of smoke above the cutting.

When a steam engine came past at night, the cutting would fill with smoke, and this would be lit up by the train's lights - and would glow.