RER A

RER A
RER A train at the underground La Défense station
Overview
Termini	Saint-Germain-en-Laye (A1), Cergy-le-Haut (A3), Poissy (A5) Boissy-Saint-Léger (A2), Marne-la-Vallée–Chessy (A4)
Connecting lines
Stations	46
Service
Type	Rapid transit/commuter rail
System	Réseau Express Régional
Operator(s)	RATP/SNCF
Rolling stock	MI 2N, MI 09
Ridership	300 million journeys per year
History
Opened	8 December 1977 (last extension in 1994)
Technical
Line length	108.5 km (67.4 mi)
Track gauge	1,435 mm (4 ft 8+1⁄2 in) standard gauge
Electrification	Overhead line:     25 kV 50 Hz AC     1,500 V DC
Route map Show geographically accurate map Legend  A3  Cergy-le-Haut   Cergy–Saint-Christophe   Cergy–Préfecture   l'Oise Neuville–Université   Conflans-Fin-d'Oise      Poissy  A5  l'Oise Achères–Grand-Cormier Achères-Ville     Saint-Germain-en-Laye  A1  Maisons-Laffitte   la Seine Le Vésinet–Le Pecq Sartrouville   Le Vésinet–Centre Chatou–Croissy Houilles Carrières-sur-Seine    la Seine Rueil-Malmaison Nanterre-Ville ↑ 25 kV AC ↓ 1.5 kV DC   Nanterre-Université   Nanterre-Préfecture          La Défense la Seine     Charles de Gaulle–Étoile           Auber          Châtelet–Les Halles        Gare de Lyon      Nation Vincennes Fontenay-sous-Bois Val de Fontenay   Nogent-sur-Marne Neuilly-Plaisance Joinville-le-Pont la Marne  Tvm    Saint-Maur–Créteil Bry-sur-Marne Le Parc de Saint-Maur Noisy-le-Grand – Mont d'Est Champigny Noisy–Champs    La Varenne–Chennevières Noisiel la Marne Lognes Sucy–Bonneuil Torcy Boissy-Saint-Léger  A2  Bussy-Saint-Georges Val d'Europe  A4  Marne-la-Vallée–Chessy all stations are accessible, except Achères–Grand-Cormier This diagram: view talk edit Show diagram map

RER A is one of the five lines in the Réseau Express Régional (English: Regional Express Network), a hybrid commuter rail and rapid transit system serving the city and suburbs of Paris, France. The 108.5-kilometre (67.4 mi) line crosses the region from east to west, with all trains serving a group of stations in central Paris, before branching out towards the ends of the line.

The initial portion of the line was built in stages between December 1969 and December 1977 by connecting two existing suburban commuter rail lines with a new tunnel under Paris: the line between Vincennes and Boissy-Saint-Léger in the east (which formerly terminated at the now-closed Gare de la Bastille), and the line between Saint-Germain-en-Laye and Nanterre in the west (which formerly used a surface alignment to the Gare Saint-Lazare that is still in use as Transilien L). The viaduct between Vincennes and the former Gare de la Bastille terminus was redeveloped into the Promenade plantée elevated park in 1993.^[1]

Since its opening, three additional branches have been added: one in the east serving Marne-la-Vallée and Disneyland Paris, and two to the west serving Poissy and Cergy.

The RER A has had a significant social impact on Paris and the surrounding region by speeding up trips across central Paris (by making far fewer stops than the Paris Métro) and by bringing far-flung suburbs within easy reach of the city centre. The line has far exceeded all traffic expectations, currently serving over 1.2 million passengers per day, on about 300 million journeys per year. It is one of the busiest rapid transit lines in Europe.