on 21 april 1931, renovation of lines 7 and 10 began. line 7 was extended from "sully-morland" on the rive droite to "porte d'ivry", and the trains of line 10 ceased use of the middle section of line 7 and instead began the use of the new tracks up to "jussieu". at the same time, the station "cardinal lemoine" was opened. traffic on line 10 diminished significantly but also became more evenly distributed across its sections.