detailing ideas needed

I haven't seen your map (yet) but depending on how sparse you want it building wise, add perhaps another 2 rows of tracks, with or without traincars, and a building behind those meant to look like a place where things would be shipped to/from using that train system.

This is just my opinion :3

If it was me, i would just put the train tracks higher, like in badwater, so i wouldnt have to think about it
Else, you could make some more tracks (and trains) parallel to the current track, and make some kind of big house / trainstation, maybe as an extension to the current wall in the back.
You could also make a high cliff all around the area and use the tunnel from lumberyard at the end of the tracks.

theyre just ideas, its up to you to decide what to do with the area

2 words.

Giant.

Sandvich.

You can always open up the valve maps in hammer and see how valve did it.

Put a big fence on the other side of the track and just have open land on the far side.
Doesn't need anything too fancy, you want the players attetion in the playable areas

I hope everything is legible!

edit: Whoops, didn't notice the image extended past the area I was looking at. It's taller than I thought! Big oversight! Well, my opinions still apply, but with taller walls. The building with the doors is fine for height, but the area with the satellite needs a taller wall, as do the new walls + building I recommended you add be taller.

Anyways, the general idea is to make any *textural* changes over prop additions, as props do not necessarily help a map's aesthetic. In fact, it oftentimes just adds clutter, the "junkyard effect," where a map looks like a hillbilly's front yard with trash strewn everywhere across it. Not to mention the problems involving FPS that can occur with too many props... So overall, try to opt for making textures more complex as well as adding any vertical/horizontal geographical lines to walls via func_details. A good example is in pl_badwater, the stretch after the first cap the cart passes by. The wall on the right is a very simplistic wall, but superb texturing + some detailing geometry on the building to add vertical lines really make it look good, but not so good that it distracts from the game or looks out of place/more like a piece of art.

You know what? Overall, for detailing, I'd recommend you take a look at badlands, badwater, and dustbowl (stage 3). All 3 share the idea you're looking for: a dusty, industrial environment. Badwater is especially good to look at regardless of type and theme of map due to the fantastic texturing on the map. It looks so good with so few props!

Also, looking at the image again, the concrete area the tracks are on, try to make that more clean and separate from the dirt around it and raise the concrete surface in relation to the dirt a few units. Not too many (4 units sounds about right). Of course, you'll need to add clips to make walking between the surfaces nice and smooth!