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Stations 46
Ridership 300,000,000 journeys per year
Opened 1977
(last extension in 1994)
Rolling stock MI 2N, MI 09
Line length 108.5 km (67.4 mi)
Track gauge 1,435 mm (4 ft 8 12 in) standard gauge
Route map
RER A.svg

Map of RER line A
Cergy – Saint-Christophe
Cergy – Préfecture
Neuville – Université
Achères – Grand Cormier
Achères – Ville
Saint Germain-en-Laye
Le Vésinet – Le Pecq
Le Vésinet – Centre
Chatou – Croissy
Nanterre – Ville
Houilles – Carrières-sur-Seine
Nanterre – Université
La Défense
Paris MétroParis Métro Line 1 TransilienTransilienTransilien Tramways in Île-de-FranceÎle-de-France tramway Line 2
Charles de Gaulle–Étoile
Paris MétroParis Métro Line 1Paris Métro Line 2Paris Métro Line 6
Paris MétroParis Métro Line 3Paris Métro Line 7Paris Métro Line 8Paris Métro Line 9 RERRER E
Châtelet–Les Halles
Paris MétroParis Métro Line 1Paris Métro Line 4Paris Métro Line 7Paris Métro Line 11Paris Métro Line 14 RERRER BRER D
Gare de Lyon
Paris MétroParis Métro Line 1Paris Métro Line 14 RERRER D TransilienTransilien SNCF
Paris MétroParis Métro Line 1Paris Métro Line 2Paris Métro Line 6Paris Métro Line 9
Val de Fontenay
Saint-Maur – Créteil
Noisy-le-Grand – Mont d'Est
Le Parc de Saint-Maur
Noisy – Champs
La Varenne – Chennevières
Sucy – Bonneuil
Val d'Europe
An MI 2N train at Charles de Gaulle – Étoile, with the SIEL information system visible.
An MS 61 train at Auber.

RER line A is one of the five lines in the RER system serving Paris, France.

The line runs from the western termini of Saint-Germain-en-Laye (A1), Cergy Le Haut (A3) and Poissy (A5) to the eastern termini of Boissy-Saint-Léger (A2) and Marne-la-Vallée – Chessy (A4).

  • Inaugurated: 12 December 1969
  • Length: 108.5 km (67.4 mi)
  • Number of stops: 46
  • Traffic (2007): 300,000,000 journeys per annum[1] (figure for both the RATP and SNCF section of the line)

Line A serves over 1,200,000 passengers per day.[2] It is formed from the connection of the Saint-Germain-en-Laye-Nanterre line in the west to the VincennesBoissy-St-Léger line in the east. Two branches were added in the west, to Poissy and the new town of Cergy-Pontoise, and in the east to the new town of Marne-la-Vallée. The two latest extensions were to Cergy-Le Haut and Disneyland Paris.

Popular success and responses[edit]

A train arriving at Auber while the previous one has not completely cleared the platform, caused by the rapid pace of SACEM.
Inside an MI 84.
MI 09 at La Defense

With more than one million passengers per workday, line A is the busiest Parisian urban rail line. Ever-increasing traffic volume and the need to ward off imminent saturation have been major factors in RATP and SNCF's planning since the inauguration of the line. At least five major capital investment decisions can be directly traced back to this issue:

  • In the early 1980s RATP contracted German conglomerate Siemens to develop a dynamic traffic control system that would remove the capacity constraints caused by conventional block traffic management. SACEM (Système d'aide à la conduite, à l'exploitation et à la maintenance) is still one of the most advanced traffic control systems and enables extremely short spacing (under 90 seconds in stations, under 2 minutes in tunnels) between trains during rush hour. Parisians have become used to the sight of a train pulling into a station as the one before it is just clearing the platform.
  • Around the same time, RATP ordered a significant number of MI79/MI84 trains to remedy premature wear and tear on MS61 stock caused by over-utilization on Line A.
  • Later in the 1980s, the need to relieve congestion on the central segment of Line A was a key factor in selecting the route of the new, fully automated Paris Métro Line 14 (also known as METEOR).
  • The same need governed the choice of the route of RER Line E in the early 1990s and is a factor in plans for that line's westward or south-westward extension.
  • A new class of double-deck trains (MI 2N series) entered service in 1998, in part a product of RATP's belief that no further infrastructure improvement (short of an extremely expensive track quadrupling of the central section) would relieve congestion on Line A. This was followed in 2011 by the MI 09 double-decker stock, aimed at replacing the aging MI 84 and MS 61 stocks.[3]


List of RER A stations[edit]

Platforms at Bry-sur-Marne.
Trains at Boissy-St.-Leger.


Lineside signal taken over by SACEM (X).


Line A provides two groups of services:

  • St Germain branch – common trunk line – Boissy branch
  • Cergy or Poissy branches – common trunk line – Marne la Vallée branch.

During off-peak hours, the Poissy – Noisy services operate every 20 minutes plus a La Défense – Noisy service every 20 minutes, and the St-Germain – Boissy and Cergy – Chessy services operate every 10 minutes.

Operations are very complex during peak periods, with an average of one train every 2 minutes (30 trains / hour) on the common trunk line in the busier direction (east to west in the morning, west to east in the evening), and one train every 2 min 30 sec in the other direction (24 trains / hour). The Marne la Vallée branch has the most intensive service.

Names of services[edit]

RER trains display a "nom de mission" or "name of service", not the name of the destination station. These are invented names designating (and distinguishing) individual services ("runs"), and are accompanied by a two-digit number, for example ZARA59 or DJIB72.

The first letter corresponds to the destination (gare d'arrivée):

Letter To Examples of names of services
D Noisy-le-Grand - Mont d'Est DYNO, DJIN, DOMI
N Boissy-St-Léger NELY, NAGA
Q Marne-la-Vallée – Chessy QUDO, QIKY, QBIK, QAHA
R La Varenne-Chennevières RHIN, RUDI
U Cergy – Le Haut UPAL, UDON, UXOL
W (empty train) WQWZ
X Le Vésinet – Le Pecq XUTI, XOUD
Y Rueil-Malmaison YCAR, YVAN
Z Saint-Germain-en-Laye ZARA, ZEUS, ZINC

The second letter corresponds to the stations served and the origin station: a letter can have different meanings, depending on the destination. For instance, second letter "E" indicates:

The third and fourth letters are used to form a pronounceable name, changed when the service number (odd 01-99 eastward, even 02-98 westward) reaches the maximum. For example, successive trains to Boissy-St-Léger are called NEGE96, NEGE98, then NELY02, NELY04, etc. Each service is uniquely identifiable, as there cannot be two "NEGE" services with the same number in the same day.

Services with the same first two letters serve the same stations, e.g. ZEBU, ZEUS and ZEMA (to Saint-Germain-en-Laye), or NEGE, NELY and NEMO (to Boissy-Saint-Léger). The letters ZZ generally indicate that the established service pattern was changed for an unspecified reason, generally a technical problem which disrupted operations.

Morning Peak[edit]

Every 10 minutes:

  • Boissy – Le Vésinet-Le Pecq, all stations except Nanterre-Ville.
  • La Varenne – St-Germain, all stations except Chatou-Croissy and Le Vésinet-Centre.
  • Marne-la-Vallée – Chessy – Cergy-le-Haut, all stations except Lognes, Noisiel, Bry-sur-Marne, Houilles and Maisons-Laffitte.
  • Marne-la-Vallée – Chessy – Poissy, all stations except Val d'Europe, Bussy-St-Georges, Lognes, Noisy-Champs and Sartrouville.
  • Torcy – Rueil-Malmaison, all stations except Bry, Neuilly-Plaisance and Nanterre-Préfecture.
  • Cergy – Torcy, all stations except Maisons-Laffitte, Houilles, Noisiel and Lognes.
  • Poissy – Chessy, all stations except Neuilly-Plaisance and Bry.
  • St-Germain – Boissy, all stations except Le Vésinet-Centre and Chatou-Croissy.
  • Le Vésinet-Le Pecq – La Varenne, all stations except Nanterre-Préfecture, Vincennes and Fontenay.

Evening Peak[edit]

Every 10 minutes:

  • Cergy – Noisy-le-Grand, all stations except Maisons-Laffitte and Houilles.
  • Poissy – Chessy, all stations except Sartrouville, Bry, Noisiel and Lognes.
  • St-Germain – Boissy, all stations except Nanterre-Ville and Nanterre-Préfecture.
  • Le Vésinet-Le Pecq – La Varenne, all stations except Vésinet-Centre and Chatou-Croissy.
  • La Défense – Torcy, all stations except Neuilly-Plaisance and Bry.
  • Chessy – Poissy, all stations except Bry and Neuilly-Plaisance.
  • Boissy – Le Vésinet-Le Pecq, all stations.
  • Noisy – Cergy-le-Haut, all stations except Houilles and Maisons-Laffitte.
  • La Varenne – St-Germain, all stations except Fontenay, Vincennes, Nanterre-Préfecture, Chatou-Croissy and Le Vésinet-Centre.

Off Peak[edit]

In both directions every 10 minutes:

  • St-Germain-en-Laye – Boissy-St-Léger.
  • Cergy-le-Haut – Marne la Vallée-Chessy.

In both directions every 20 minutes:

  • Poissy – Noisy-le-Grand - Mont d'Est.
  • La Défense – Noisy-le-Grand - Mont d'Est.

Off-peak, a train is scheduled every 3 minutes 20 seconds between La Défense and Vincennes in both directions.

See also[edit]


  1. ^ RATP. "Schéma directeur du RER A" (PDF) (in French). Archived from the original (PDF) on 1 March 2013. Retrieved 4 July 2012. 
  2. ^ (in French) RER A – "10 secondes de retard, 15.000 voyageurs affectés !" Archived 12 October 2009 at the Wayback Machine.
  3. ^ "MI 09 tout neuf" [MI 09 Brand New] (in French). France: MetroPole. 5 December 2011. Archived from the original on 16 January 2012. 

External links[edit]

  • Media related to RER A at Wikimedia Commons