single word requests - Use of peri- prefix where sub- and super- are commonly used (Or, is periterranean valid?)

While trying to construct a description of the various train networks of London, I wanted to use the word periterranean to mean "close to the ground", with reference to subterranean (under the ground) and, I suppose, superterranean (above the ground).

I am aware that superterranean would typically cover both the "on the ground" and "above the ground" cases, but I wanted a word to distinguish, say, the Docklands Light Railway (much of which runs on raised tracks) from the London Overground (much of which runs on surface tracks). Of course, both should be distinguished from the London Underground, even though 55% of the Underground is, in fact, above ground.

Extensive Google searches failed to bring up anything of relevance, so my question is this: Are there any examples of periterranean used in the context I have described, and, if not, what would be a more appropriate word?

Answer

I'm afraid that would be a bad choice. Greek peri- means "around, about", which is not what you want. Cf. perimeter, perihelion, periphery, etc. In Latin, the prefix used to indicate "near" would be ad-, which assimilates to at- before a t-. So atterranean would be properly formed and somewhat near your intended meaning.