Réseau Express Régional
The Réseau Express Régional, commonly abbreviated RER, is a hybrid commuter rail and rapid transit system serving the city centre of Paris and its suburbs. It acts as a combined city centre underground rail system and suburbs-to-city-centre commuter rail, similar to the S-Bahn in Germany, Austria and Switzerland, S-train in Copenhagen, the Pendeltåg in Sweden, the Overground and Elizabeth Line in London, S Lines in Milan, plus many other commuter rail networks around the world. It is part of the network of transport services managed by Île-de-France Mobilités.
Conceived of as a métropolitain express during the mid-1930s, the scheme was revived in the 1950s and construction began in the early 1960s. The RER was not fully conceptualised until the completion of the Schéma directeur d'aménagement et d'urbanisme in 1965. The RER network, which initially comprised two lines, was formally inaugurated on 8 December 1977 in a ceremony that was attended by President Valéry Giscard d'Estaing. A second phase of construction commenced at the end of the 1970s which saw additional lines constructed along with extensions to the original two. The RER is operated partly by RATP Group, the authority that operates most of the public transport in Paris, and partly by the SNCF Voyageurs, France's national rail operator.
As of 2025, the network consists of five lines: A, B, C, D and E. The network has 257 stations and has interchanges with the Métro, tramway and commuter rail within the City of Paris and the suburbs. The lines are identified by letters to avoid confusion with the Métro lines, which are identified by numbers. The network continues to expand: RER E, which opened in 1999, is planned for westward extension toward La Défense and Mantes-la-Jolie in two phases between 2024 and 2026. The performance of the RER has made it a model for proposals to improve public transport within other cities. In November 2022, the French President Emmanuel Macron announced the creation of additional RER systems that will serve the ten largest French metropolises by 2040.
Characteristics
The RER contains 257 stations, 33 of which are within the city of Paris, and runs over of track, including underground. Each line passes through the city almost wholly underground and on tracks dedicated to the RER, but some city center tracks are shared between line D and line B. The RER is operated partly by RATP, the authority that operates most public transport in Paris, and partly by SNCF, the national rail operator. The system, which is structured in a traditional radial arrangement, operates a through-service and uses a single fare model that works seamlessly with several other public transit systems. Total traffic on the central sections of lines A and B, operated by RATP, was 452 million people in 2006; in the same year, total traffic on all Paris area commuter lines operated by SNCF was 657 million.RATP manages 65 RER stations, including all stations on Line A east of Nanterre-Préfecture and those on the branch to Saint-Germain-en-Laye. It also operates stations on Line B south of Gare du Nord. Other stations on the two lines and those on lines C, D and E are operated by SNCF. Of the RER stations operated by RATP, 9 have interchanges with Métro lines, and 9 allow transfer to SNCF's Transilien service. In comparison to the Metro, the RER provides better coverage of Paris's suburbs and typically operates at higher speeds and with greater distances between stations. Within the city center, RER services practice limited stop operations.
History
Origins
Its roots are in the 1936 Ruhlmann–Langewin plan of the Compagnie du chemin de fer métropolitain de Paris for a "métropolitain express". The company's post-war successor, RATP, revived the scheme in the 1950s, and in 1960 an interministerial committee decided to go ahead with the construction of an east–west line. Subsequently, the central part of the RER was completed between 1962 and 1977 in a large-scale civil engineering project whose chief supervisor was Siavash Teimouri. The construction of the RER was a major undertaking, being highly visible to both Parisians and visiting tourists at various sites across the city for an extended period.As its instigator, RATP was granted authority to run the new link. The embryonic RER was not properly conceived until the 1965 Schéma directeur d'aménagement et d'urbanisme, which envisioned an H-shaped network with two north–south routes. Between 1969 and 1970, RATP purchased the Vincennes and Saint-Germain lines from SNCF, as the basis for the east–west link. Only a single north–south route crossing the Left Bank has so far come to fruition, although the Métro's line 13 has been extended to perform a similar function.
The RER's first phase of construction during the 1960s and 1970s was marked by scale and expense. In 1973 alone, FRF 2 billion were committed to the project in the budget, equating to roughly €1.37 billion in 2005 terms, and closer to double that as a proportion of the region's economic output. The construction cost was controversial at the time of its construction. This initial investment, along with subsequent spending, was partly financed by the versement transport, a local tax levied on businesses that was introduced in July 1971. It has remained in effect into the twenty-first century.
First phase
During the first phase of construction, the Vincennes and Saint-Germain lines became the ends of the east-west Line A, the central section of which was opened station by station between 1969 and 1977. On its completion, Line A was joined by the initial southern section of the north-south Line B. Both Lines A and B were intentionally designed to converge with as many of the existing commuter lines as possible as to maximise its usefulness to existing travelers. During this first phase, six new stations were built, three of which are entirely underground.Construction was inaugurated by Robert Buron, then Minister for Public Works, at the Pont de Neuilly on 6 July 1961, four years before the publication of the official network blueprint. The rapid expansion of the La Défense business district in the west made the western section of the first line a priority. Nation, the first new station, was opened on 12 December 1969 and became for the next 8 years the new western terminus of the Vincennes line. The section from Étoile to was opened a few weeks later. It was later extended eastward to the newly built on 23 November 1971, and westward to Saint-Germain-en-Laye on 1 October 1972. The latter extension was achieved by a connection to the existing Saint-Germain-en-Laye line, the oldest railway line into Paris, at Nanterre.
The RER network was inaugurated on 8 December 1977 with the joining of the eastern -Boissy segment and the western – segment at. The inauguration was attended by President Valery Giscard D'Estaing. The southern Ligne de Sceaux was simultaneously extended from Luxembourg to meet Line A at Châtelet – Les Halles, becoming the new Line B. The system of line letters was introduced to the public on this occasion, though it had been used internally by RATP and SNCF for some time.
Second phase
A second phase of construction commenced at the end of the 1970s, which was carried out at a slower pace than the first phase. SNCF gained the authorisation to operate its own routes, which became lines C, D and E. Extensive sections of suburban tracks were added to the network, but only four new stations were built.During 1979, Line C was added, although it almost entirely comprised existing SNCF lines. The main civil engineering works performed involved the construction of a connecting link between Invalides and Musée d'Orsay. In 1981, Line B was extended through to Gare du Nord via a new deep tunnel from Châtelet – Les Halles. It was later extended further northward. By 1992, a total of 233 miles of track was operational, while a further 94 miles were under construction.
During 1995, Line D was completed; its primary feature was a purpose-built deep tunnel between Châtelet – Les Halles and Gare de Lyon. No new building work was necessary at Châtelet – Les Halles, as additional platforms for Line D had been built at the time of the station's construction 20 years earlier. In 1999, Line E was added to the network, connecting the north-east with Gare Saint-Lazare by means of a new deep tunnel from Gare de l'Est.
Maps
Rolling stock
The predominance of suburban SNCF track on the RER network explains why RER trains use overhead line power and run on the left, like SNCF trains, contrary to the Métro where trains use third rail power and run on the right. RER trains run by the two different operators share the same track infrastructure, a practice called interconnection. On the RER, interconnection required the development of specific trains capable of operating under both 1.5 kV direct current on the RATP network and 25 kV / 50 Hz alternating current on the SNCF network. The MS 61 series can be used only on the 1.5 kV DC network.The RER's tunnels have unusually large cross-sections. This is due to a 1961 decision to build them according to a loading gauge standard created by the Union Internationale des Chemins de Fer, with space for overhead catenary power supply to trains. Single-track tunnels measure across and double-track tunnels up to, meaning a cross-sectional area of up to, larger than that of the stations on many comparable underground rail networks.
The first RER rolling stock in fact predated the formation of the RER by 40 years, with the Z 23000 stock used on the ligne de Sceaux from 1937 until 27 February 1987. In 1965 the Z 5300 train was introduced, followed by the MS 61 in 1967, MI 79 in 1980,Z 5600 In 1982, MI 84 and Z 8800 in 1985, Z 20500 in 1988, MI 2N in 1996, Z 20900 in 2001, Z 50000 in 2009,MI 09 on 5 December 2011 and Regio 2N in 2012. In 2017, it was announced that an consortium comprising Alstom and Bombardier Transportation had been selected to supply 255 X’Trapolis Cityduplex double-deck electric multiple units to replace aging rolling stock on both lines D and E under a €3.75 billion arrangement. In April 2023, 60 additional Cityduplexs were ordered to increase service frequency.
Many services are performed by double-decker train sets, usually operating in double formations.