David Johnson <trainman@ozemail.com.au> wrote in message 38E73719.FCF702BA@ozemail.com.au">news:38E73719.FCF702BA@ozemail.com.au... > I think the system calculates the estimated arrival time from the > train's position on the track circuits. That sounds more logical. Hence the reason why the countdown to arrival occasionally "bounces" back and forth between minutes.