If you have ever approached a large intersection in a sizable city, but the traffic lights are all blinking red, this would be a System is out of control situation. All vehicles must stop at the intersection barrier lines (crosswalk), then proceed when it is safe. When the System is in control, the intersection's right-of-way is being controlled by the lights, and the vehicles are flowing through the intersection in one direction while the vehicles in the crossing direction are waiting their turn... the system controls the flow.