obstructed

The vehicles standing still right now because this one is in their way.

Asked of the vehicle rather than computed here, because being in the way is a fact about a substrate: a guide path answers it from what this vehicle holds and who is waiting for it, and a substrate where vehicles do not share space answers "nobody" -- which is the honest reading of a free path rather than a gap, since a model that asserts vehicles do not get in each other's way has asserted exactly this.

Read it again after time passes -- it is a live query, not a snapshot taken when the vehicle stopped.