My understanding of the rail community is that they mostly care about trackage, not specific services. So if I rake Amtrak through Orlando, it makes sense that I clinch the SunRail commuter service on the same tracks.
But if you ride the DC Metro Blue Line out to Franconia-Springfield you don't clinch the adjacent VRE/Amtrak mileage since while parallel and in the same ROW it's not the same tracks (has to be physically separate, even, since one is FRA-regulated and the other isn't).
This is what we've been moving to implement and I generally agree with it: concurrency should be mapped and detected if it's the same tracks, even if it's two different systems. But if it's different tracks, no concurrency.
This is consistent with how we handle things for roads too, where if they physically share the same pavement they're marked concurrent even if they're different classes, but if they're only parallel (e.g. state route follows the frontage roads of an interstate), they're not.
And as far as "but we're mapping services, not tracks", I see no problem, this too is consistent: a given numbered route may follow multiple distinct named roads, but it doesn't matter because we map the route and not the roads. No one thinks that you shouldn't get credit for I-94 mileage by clinching I-80 because we're mapping I-80 and I-94, not the Borman Expressway. Nor does anyone think I-94 should be cut up into multiple routes to avoid needlessly running it concurrent with other interstates.
Likewise, fair game to get credit for Metro-North by clinching Amtrak even though we're mapping those services and not The Northeast Corridor. Whether it's a train service or a road route, what is mapped matches its extent, and if it shares space with another you get credit for both.
