The example I can always give you is the London Underground.<br>The indicator says 3 mins - and stays that way for 5mins. Why ?<br>This is because the train IS 3 mins away but it is not moving.<br>And during those 5 mins the train remains stationary but LED board still accurately reports the next train is 3 mins away from the station.<br>The board is accurate but it is not telling you what you think it is telling you.