beginning at the western terminus of line 10, the first train that leaves the station "porte d'auteuil" heads towards the terminus of "gare d'austerlitz". at this time, passengers may ride on the turn-around track, which is closed to passengers for the rest of the day. siel, "système d'information en ligne", gives passengers on the platforms the time-to-arrival of the next two trains, and has been operational since 1 july 2008.