RER B is one of the five lines in the Réseau Express Régional, a hybrid suburban commuter/rapid transit system serving Paris, France and its suburbs. The RER B line crosses the Paris region from north to south, with all trains serving a group of stations in central Paris, before branching out towards the ends of the line. The line runs from the northern termini Aéroport Charles de Gaulle and Mitry-Claye to the southern termini Robinson and Saint-Rémy-lès-Chevreuse.
The southern part of the line is operated by the RATP, and the northern part by the SNCF. Trains are owned by either company. Until December 2009, drivers changed at Gare du Nord; RATP and SNCF drivers now operate their trains along the full length of the line. Trains moving from one network to the other at this station is known as the Interconnexion. Technical difficulties of the Interconnexion include the shared tunnel with RER D between Châtelet – Les Halles and Gare du Nord, and the fact that while the SNCF part in the northern suburbs use 25 kV AC, the RATP part uses 1500 V DC, forcing the use of dual-voltage trains.
Chronology
Line B was the product of the connection in 1977 of the Ligne de Sceaux terminus, Luxembourg, with the Gare du Nord via Châtelet – Les Halles. In 1988 St-Michel – Notre-Dame station between Luxembourg and Châtelet – Les Halles was opened to provide connection with RER C and Métro Line 10 at Cluny – La Sorbonne, a station which had been closed since the beginning of World War II and was entirely renovated for the occasion.
9 December 1977: The "ligne de Sceaux" is extended to Châtelet-les Halles,, and becomes the RER B.
10 December 1981: The line is extended from Châtelet-les Halles to Gare du Nord, . RATP trains to Robinson and Saint-Rémy-lès-Chevreuse make end-to-end connections with SNCF trains to Aulnay-sous-Bois, Paris-Charles de Gaulle Airport and Mitry,, but without through working due to a difference in electrical system.
17 February 1988: The station St-Michel – Notre-Dame is inaugurated between Luxembourg and Châtelet in order to offer a quick connection with metro line 10 and the RER C.
28 January 1998: "La Plaine – Voyageurs" station is moved by a few hundred meters and renamed "La Plaine – Stade de France" in order to reflect the name of the Stade de France for the 1998 FIFA World Cup held in Paris.
RER B is operated by 117 sets of the MI 79 series and 31 sets of the MI 84 series. These are to be replaced from 2025. Past fleet include the MS 61, which operated on the line from 29 June 1967 to 28 February 1983, and the :fr:Z 23000|Class Z 23000, which operated from 16 November 1937 to 27 February 1987.
