Until March, 2013; light maintenance of the MP 89CC rolling stock of Line 4 was handled within the station of Porte d'Orléans (CDT). Platform 2 of the station (in the direction of Porte de Clignancourt contains inspection pits, which allow routine light maintenance work and troubleshooting of the first level. Both Porte d'Orléans and Porte de Clignancourt also contain loop tracks where trains can be stored overnight (although many trains are stored within the main tunnels due to a lack of a sufficient garage). This protocol changed when a new garage located south of the new station Mairie de Montrouge opened. Track 3 of station Porte d'Orléans will eventually be dismantled and covered over to make way for a new access point into the station.