In the first photo we have a oil derrick that is on the side of a track junction. Is it in the best location. NO but the oil derrick could have been there first.
The ground cover is not seen much but can be seen between the track and the embankment. You should use something close to the color of natural are you are modeling. Then add some foliage and some rocks.
Now the track ballast has been replace at some point from a basalt to pink lady.
As you can see at the bas of the embankment there are rocks that have fallen down the hill. Although the rock do not match the color if the embankment the rock may not be from the local area but from some train passing by.
So you should not always use the rock that match’s the local color in your scene.
Now you should always consider add some other colors to the scene like the brown that was paint on the embankment. Nature is messy and we surprise your with the weird color combos that are found in the same small area.