Well, those webs that I get on the layout are the same as the ones in the rest of the house, and there are spiders on them.
Often times cobwebs get stuck in spider webs to. after all, cobwebs are dust.
I don't mind spiders in the house, but it does "bug" me when I get cobwebs in the layout room. I don't know if they're the ones responsible for the webs, but the ones that I see most often on the layout are very small (about a quarter of the size of the head of a pin, and are orangey-red. The other common ones here are just house spiders (like house cats, only nicer, 'cause they don't shed),fairly small, pale-coloured ones.
I don't recognize your small orange ones (they might be unique to your part of North America), but it seems those other "house spiders" are pretty much universal. I don't really see them coming down by my layout though.
Then again, your layout is massivesign1 That big Gern industry's silos look like a good spot for a web.
I will say though, that the webs on your loading dock look from the photos to be just cobwebs from dust though. Even house spiders have a structure to their webs, even though they can look totally random. Its possible your RS3 crashed through a web, but i have to say it also has that cob web appearance, althought it is harder to see.
In this photo, you can see a classic cob web. this is all dust. its all small hairs and chains of static dust that holds together in what looks to be a cob web.

regardless of causation, alittle dusting will probably help remove most cobwebs from the layout.
My favourites are the black and white jumping spiders - I don't think that they even build webs, but they're very aggressive. If you have a good complement of spiders, chances are that you at least don't have too many centipedes, as centipedes will kill spiders. I'll take the spiders any day.:-D
Wayne
Yeah, the jumping spiders are my favorite to. they aren't as threatening as wolf spiders, and they seem more interesting anyway. They do "bungie jump" though, and so anytime they do leap they do leave some silk behind, but its nothing.