Commissioned in 1999, the RER E linked Haussmann Saint-Lazare (Paris 9th) to Chelles Gournay (77) and Tournan (77).
The extension to the west to Mantes-la-Jolie (78) will improve service to the west of the Ile-de-France region by offering an alternative to the RER A, the central section of which is saturated during rush hour. It consists of redeveloping the existing line between Mantes-la-Jolie and La Défense and drilling a tunnel from La Défense to Haussmann Saint-Lazare.
In addition, the master plan for the RER E to the east approved in 2016 by Île-de-France Mobilités commits to a plan for the renewal of this line as well as line P.

Plan
