Public restrooms in Russia in general are terrible, dirty, inoperative and often have no toilet paper or use recycled newspaper even in public buildings and unrenovated offices. This is true in trains & public places.
TYPHint: Carry a couple of small packs of tissues (Kleenex) or even better a half-roll in your handbag or briefcase. Western toilet paper is now available in most supermarkets. Restrooms can be identified by the following signs: WC, or "Òóàëåò (Tualet)". Men by "Ì" and women by "Æ". Paid restrooms should be cleaner and have at least the basic amenities.