Fable
The ferry dock hung a status board on every boat
The river mouth ferry was simple at first. When a boat arrived, it was loaded; when full, it departed; when it reached the other shore, it was unloaded. The old boatman knew from experience what to do next. Later, cargo included refrigerated containers, dangerous goods, urgent items and packages awaiting inspection. Boats also had maintenance, refueling, tide waiting and rechecking situations. Dispatching by shouting began to go wrong frequently. The manager first hung a large wooden sign at the dock: everyone, please follow the rules. But everyone understood the rules differently; some boats departed before inspection was complete, and some boats that could clearly leave kept waiting for approval.
The second approach was to have all exceptions ask the steward. As a result, the steward was surrounded, the fleet formed a long queue, and even the simplest loading and unloading had to wait for a verbal permit.
A young shipwright listed every possible position a ship could be in: awaiting loading, loading, awaiting inspection, awaiting approval, ready to sail, sailing, arrived at port, exception, closed. Each position allowed only a few possible next steps.
He also specified transition conditions: only after passing inspection could something move from pending inspection to seaworthy; a rejected approval must return to pending loading; a storm warning would move in-transit to exception handling.
With status tags, the boatman no longer had to guess whose orders to follow now. The whole setup could also record why a boat was stuck, who triggered the transition, and whether it could be retried or rolled back.
The ferry crossing eventually stabilized, not because the boatmen suddenly became more cautious, but because the complex process was broken into finite states and clear transitions, confining the chaos within inspectable boundaries.
When the status board was first hung, the old boatman complained it was rigid. It was not until a dangerous goods ship was stopped at pending approval for lacking a review stamp that everyone realized the wooden board was not adding trouble, but blocking habitual actions at key points on everyone's behalf.
Later, in every incident review, the manager no longer asked "what was who thinking," but rather where the boat was at the time, which transitions were allowed, and who triggered the next step. Arguments at the ferry decreased because every step had clear boundaries. Finite positions and finite transitions let everyone know what they could do—and when they had to stop.