RER E is one of the five lines in the Réseau Express Régional (English: Regional Express Network), a hybrid commuter rail and rapid transit system serving Paris, France and its suburbs. The 52.3-kilometre (32.5 mi) RER E line travels between Paris and eastern suburbs, with all trains serving the stations in central Paris, before branching out towards the ends of the line. The line runs from the western terminus Haussmann–Saint-Lazare (E1) to the eastern termini Chelles–Gournay (E2) and Tournan (E4). It is operated by SNCF. Originally referred to as the Est Ouest Liaison Express or EOLE (English: East West Express Link), RER E is the newest line in the system opening in 1999, with the extension in 2003, and further extensions to the west currently under construction (in 2024 to Nanterre-La Folie, in 2026 to Mantes-la-Jolie). From Wikipedia