Access - shooting range

I have a forest track with yellow/black signs saying (in danish):

Shooting range
No admittance
when the sphere is hoisted

The sphere being the signal that there are people shooting there. The rest of the time, it’s allowed to go that way (if it wasn’t allowed at all, the sign would stop after “no admittance”).

How should I tag this track?

I don’t know the answer to this, but some years ago I wandered through the Prattigau when the cantonal shooting festival was taking place. I very rapidly learnt why shooting ranges are marked on Swiss Topo maps. So this question should be of fairly general interest. See http://wiki.openstreetmap.org/wiki/Tag:sport%3Dshooting. The notion of some kind of barrier node at the point of the notices seems sensible. An access tag with a value like “conditional” on the way would be another (non-exclusive) possibility.