Besides which, is it even legal for active crossings to have no crossing gates? And are there any other known instances of yield signs at active crossings?
Easily over half the crossings in my general area don't have gates. They've upgraded signals at many crossings, but rarely do they add gates.
This active crossing: https://maps.app.goo.gl/TR4FPQJnjpBcCBiB9 , doesn't have gates, signals, or a stop/yield sign.
Is this crossing active in name only or is it actually used regularly?
If it was "active in name only", it'd most likely be filed as "no train traffic" with the FRA, as the
since ripped NS AG Branch in Gadsden, AL, was.
My guess is that the line, even if it doesn't have any customers directly on it, still sees the occasional storage or transloading move, which a lot of shortlines across the US do to make money. My local shortline, the Huntsville & Madison County Railroad, is one-such example, as they no longer have any customers directly on either of their lines, but here in Huntsville you can still semi-regularly catch them running twice a day a few days every week (sometimes more) to pull stored/transloaded cars in or out from the south end of their line. Of course, if the line is used for car storage, said storage moves might not even be once a week. They could easily be once a month, or a handful of times a year (at best).
That being said, looking at the crossings in question, the rails around the crossing seem rather dull in the street view images and the tracks on the edges of the crossing grade are very much rusty, so, if there is any service, it's rather infrequent.