RER A

RER A
Overview
Stations	46
Ridership	300,000,000 journeys per year
Operation
Opened	1977 (last extension in 1994)
Rolling stock	MS 61, MI 84, MI 2N, MI 09
Technical
Line length	108.5 km (67.4 mi)
Route map Geographically accurate path of the RER A

RER A
Legend
A3  Cergy – Le Haut Cergy – Saint-Christophe Cergy – Préfecture  A5  Neuville – Université Poissy Conflans – Fin d'Oise Achères – Grand Cormier Achères – Ville  A1  Saint-Germain-en-Laye Le Vésinet – Le Pecq Maisons-Laffitte Le Vésinet – Centre Chatou – Croissy Sartrouville Rueil-Malmaison Nanterre – Ville Houilles – Carrières-sur-Seine Nanterre – Université Nanterre-Préfecture La Défense 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 Bry-sur-Marne Saint-Maur – Créteil Noisy-le-Grand – Mont d'Est Le Parc de Saint-Maur Noisy – Champs Champigny Noisiel La Varenne – Chennevières Lognes Sucy – Bonneuil Torcy Boissy-Saint-Léger Bussy-Saint-Georges  A2  Val d'Europe Marne-la-Vallée – Chessy  A4

An MI 2N at Charles de Gaulle – Étoile. You can see the SIEL information system.

An MS 61 at Auber.

The RER A is one of the five lines in the RER rapid transit system serving Paris, France.

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

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

Line A is one of the world's busiest lines with over 1,200,000 passenger/day. Line A is formed from the connection across Paris of the Saint-Germain-en-Laye-Nanterre line in the west to the Vincennes – Boissy-St-Léger line in the east. Two branches were added in the West, to Poissy and the new town of Cergy-Pontoise, and another in the East, to the new town of Marne-la-Vallée. The two latest extensions of the line were to Cergy-Le Haut and Disneyland Paris.

Popular success and responses

A train arriving in the station Auber while the previous one hasn't 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, RER A is the busiest of all Parisian RER and metro lines. 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 A. 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. This system, called SACEM (Système d'aide à la conduite, à l'exploitation et à la maintenance), remains today one of the world's 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 had to order a significant number of additional MI79/MI84 trains to remedy premature wear and tear on its existing MS61 rolling stock caused by over-utilization of 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 Line 14 (also known as METEOR) of the Métro.

• The same need governed the choice of the route of RER Line E in the early 1990s and is a factor in current plans for that line's westward or south-westward extension.

• An entirely new class of double-decker 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) would relieve congestion on Line A. This is followed later in 2011 by the MI 09 double-decker stock (which is aimed at replacing the aging MI 84 and MS 61 stocks).

One simple (if partial) solution to the congestion problem that has never been implemented is a change in the seating configuration inside the trains themselves. The RER is unusual among high-capacity urban train networks in its attachment to "transversal" (front and back facing) seating. A change to "longitudinal" (sideways window-lining) seating typically reduces the number of seats by 10% but increases standing room by 30%. The result is increased capacity and a less cramped ride for those without seats.

Chronology

• 14 December 1969: The Paris subway operator, the RATP, buys the "ligne de Vincennes" from the SNCF which connected Bastille with Boissy-Saint-Léger in the east. A new 2.5-km tunnel is built between Vincennes and Nation, which replaces Bastille as the terminus. Total length of segment: 17.5 km.
• 21 February 1970: The RATP buys the "ligne de St-Germain" from the SNCF which connected St-Lazare train station with Saint-Germain-en-Laye in the west. A new tunnel is opened between La Défense and the Place de l'Étoile, which replaces St-Lazare as the terminus. Shuttle ("navette") service is operated La Défense – Étoile, 4 km.
• 23 November 1971: Tunnel opened Étoile – Auber, 2 km. Shuttle service extended to operate La Défense – Auber.
• 1 October 1972: Tunnel opened La Défense – Nanterre-Université, 2 km. Shuttle service extended on the "ligne de St-Germain" (La Défense – Saint-Germain-en-Laye, 13 km) to operate Saint-Germain – Auber.
• October 1973: New underground station, Nanterre-Préfecture, opened between La Défense and Nanterre-Université.
• 9 December 1977: Both lines are connected with a new 6-km tunnel giving birth to the RER A line, Saint-Germain – Boissy-Saint-Léger, 42.5 km total. Two new stations were inaugurated: Châtelet-les Halles and Gare de Lyon. A new branch, "ligne nouvelle de Marne-la-Vallée," 8.5 km, was opened in the east from Vincennes to Noisy-le-Grand.
• 19 December 1980: The "ligne nouvelle de Marne-la-Vallée" was extended from Noisy-le-Grand to Torcy, 9 km.
• 29 May 1988: New service, "Interconnexion Ouest," Cergy-St-Christophe – Marne-la-Vallée (Torcy), 47 km total. Included new branch in the west from Nanterre-Préfecture to Cergy-St-Christophe, 15.5 km.
• May 1990: Another branch was created in the west from Maisons-Laffitte to Poissy, 8.5 km.
• 1 April 1992: The Marne-la-Vallée line was extended from Torcy to Marne-la-Vallée-Chessy, 11 km, in order to create a direct link from the centre of Paris to Disneyland Paris.
• 29 August 1994: Extension opened Cergy-St-Christophe – Cergy-Le Haut, 2.5 km. New station, Neuville-Université, opened. Located between Conflans-Fin-d'Oise and Cergy-Préfecture.
• 10 June 2001: New station, Val-d'Europe, opened. Located between Bussy-St-Georges and Marne-la-Vallée-Chessy.

List of RER A stations

Cergy-le-Haut.

Platforms at Bry-sur-Marne.

Trains at Boissy-St.-Leger.

• A1
  • Saint-Germain-en-Laye
  • Le Vésinet – Le Pecq
  • Le Vésinet – Centre
  • Chatou – Croissy
  • Rueil-Malmaison
  • Nanterre – Ville
  • Nanterre – Université
• A3, A5
  • A3
    • Cergy – Le Haut
    • Cergy – Saint-Christophe
    • Cergy – Préfecture
    • Neuville – Université
    • Conflans – Fin d'Oise
    • Achères – Ville
  • A5
    • Poissy
    • Achères – Grand Cormier
  • Maisons-Laffitte
  • Sartrouville
  • Houilles – Carrières-sur-Seine
• Nanterre – Préfecture
• La Défense
• Charles de Gaulle – Étoile
• Auber
• Châtelet – Les Halles
• Gare de Lyon
• Nation
• Vincennes
• A2
  • Fontenay-sous-Bois
  • Nogent-sur-Marne
  • Joinville-le-Pont
  • Saint-Maur – Créteil
  • Le Parc de Saint-Maur
  • Champigny
  • La Varenne – Chennevières
  • Sucy – Bonneuil
  • Boissy-Saint-Léger
• A4
  • Val de Fontenay
  • Neuilly-Plaisance
  • Bry-sur-Marne
  • Noisy-le-Grand – Mont d'Est
  • Noisy – Champs
  • Noisiel
  • Lognes
  • Torcy
  • Bussy-Saint-Georges
  • Val d'Europe
  • Marne-la-Vallée – Chessy

Operation

Lineside signal taken over by SACEM (X).

Branches

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-St-Leger and Cergy – Chessy service operates every 10 minutes.

Operations are very complex during peak periods, with an average of one train every 2 minutes (theoretically 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

RER trains do not display the name of the destination station, but instead display a "nom de mission" or "name of service." These are, literally, names used to designate (and distinguish) individual services ("runs"), and are accompanied by a two-digit number, for example ZARA59 or DJIB72.

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

Letter	Station name	Examples of names of services
B	La Défense	BYLL, BORA, BTON
D	Noisy-le-Grand -Mont d'Est	DYNO, DJIN, DOMI
N	Boissy-St-Léger	NELY, NAGA
O	Torcy	OKEY, ORKA, OFRE
Q	Marne-la-Vallée – Chessy	QUDO, QIKY, QBIK, QAHA
R	La Varenne-Chennevières	RHIN, RUDI
T	Poissy	TERI, TJAC, TIKY
U	Cergy – Le Haut	UPAL, UDON, UXOL
W	(empty train)
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 original station. These can be different depending on the destination station. For instance, should the first letter be "Z" or "N", the second letter "E" indicates that the train calls at all stations (omnibus), on the route Saint-Germain-in-Laye – Boissy-St-Léger (services NELY or ZEUS). However, should the first letter be "Q", the letter "E" indicates that the train goes from Poissy to Marne-la-Vallée – Chessy, and does not stop at Neuilly-Plaisance and Bry-sur-Marne (service QENO).

The third and fourth letters are used to form a pronounceable name. These letters are changed when the service number (from 01 to 99 eastward, from 02 to 98 westward) reaches the maximum. For example, some successive trains going to Boissy-St-Léger are respectively called NEGE96, NEGE98, then NELY02, NELY04, etc. This makes each service uniquely identifiable, as there cannot be two services "NEGE" with the same number in the same day. Therefore, services with the first two letters identical serve the same stations, e.g. ZEBU, ZEUS and ZEMA (local trains with destination Saint-Germain-en-Laye), or NEGE, NELY and NEMO (local trains with destination 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 Periods

Each of these services operates 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 stops except Bry, Neuilly-Plaisance and Nanterre-Préfecture.
• Cergy – Torcy, all stops except Maisons-Laffitte, Houilles, Noisiel and Lognes.
• Poissy – Chessy, all stops except Neuilly-Plaisance and Bry.
• St-Germain – Boissy, all stops except Le Vésinet-Centre and Chatou-Croissy.
• Le Vésinet-Le Pecq – La Varenne, all stops except Nanterre-Préfecture, Vincennes and Fontenay.

Evening Peak Periods

Each of these services operates every 10 minutes:

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

Off-Peak Hours

Each of these services operates in both directions every 20 minutes:

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

Each of these services operates in both directions every 10 minutes:

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

During the off-peak operation, a train is scheduled every 200 seconds (3 minutes 20 seconds) between La Défense and Vincennes in both directions.

See also

• List of stations of the Paris Métro
• List of stations of the Paris RER

External links

• RATP official website (in French)
• RATP official website (in English)
• Interactive map covers the Paris metro map, the Paris bus map, and the RER map in the Ile-de-France region (from RATP's website)