To whom it may concern,
is RER C under maintenance during Aug. 1-7?
Can I take the line to Chateau de Versailles on Aug. 4?
Paris Train C (RER C) construction for Aug 1 - 7, 2017 only affects the branch between Gare d'Austerlitz and St. Martin d'Etampes. The branch of Paris Train C towards Versailles is on a different branch and is unaffected by the construction works.
See the Paris Train C map for more details on which branch of the RER C line you will be taking.