Why do a Tzen between the "La Treille" station in Viry-Chatillon and the Corbeil-Essonnes RER station?

To meet the travel needs of the territory in the most appropriate way while supporting its development, a Tzen link will be created between Viry-Chatillon, Grigny, Ris-Orangis, Évry-Courcouronnes and Corbeil-Essonnes. The implementation of the Tzen 4 on a shorter line than the current line 402 follows various studies identifying the section between the "La Treille" station in Viry-Chatillon and the Corbeil-Essonnes RER station as central. A ridership survey conducted in 2010 confirms the importance of this link: 82% of the trips on line 402 are made between the stations "La Treille" and "Lycée Robert Doisneau". On the other hand, the Épinay-sur-Orge / La Treille and Tarterêts / Le Coudray-Montceaux sections have a much lower attendance.
The Tzen 4 will therefore replace line 402 between the "La Treille" station in Viry-Chatillon and the Corbeil-Essonnes RER station.