isObstructingNow

True when at least one vehicle is being held up by this one at this instant.

The name says now because that is the whole of what it means, and the difference matters. A vehicle becomes blocked only when it tries to enter the next zone and is refused, so at the moment a vehicle stops, nobody has tried yet and the answer is no. Twenty minutes later three carts are queued behind it and the answer is yes. Both answers are correct.

So a policy that asks this as its first line never tows. Measured on the chapter's shop: over sixteen breakdowns, asking at the instant the vehicle stopped found an obstruction not once, on a layout where leaving it in the aisle cost the healthy cart 77% of its time blocked. Nothing errors; the model simply behaves as though towing were not configured.

A realistic policy never meets this, because it cannot decide anything until somebody has been told, been free, and walked to the vehicle -- and by then the queue is real. Ask this one after time has passed. To decide before any has, ask isOnAThroughRoute, which is a fact about the layout and is true the instant the vehicle stops.