Chronology •
21 April 1908: A first section of the line was inaugurated to the north of the
Seine between Porte de Clignancourt and Châtelet. •
30 October 1909: A second section of the line was inaugurated south of the Seine between Porte d'Orléans and Raspail. •
9 January 1910: Both sections were linked by a new tunnel between Châtelet and Raspail. Line 4 was the first line crossing the Seine river underground. •
1967: The rails were converted in order to cater for rubber-tired trains. The MP 59 rolling stock replaced the steel-wheeled Sprague-Thomson stock. •
3 October 1977: The station Les Halles was rebuilt to interchange with the new RER network. •
23 May 2011: Cascading of MP 59 to MP 89CC rolling stock began. •
21 December 2012: The last MP 59 (#6021) was withdrawn after 45 years of service on Line 4. •
23 March 2013: Extension south to Mairie de Montrouge officially opened to passengers, marking the first extension of Line 4 since its inception. •
2016: Automation work begins. •
13 January 2022: Extension south to Bagneux-Lucie Aubrac officially opened to passengers. •
12 September 2022: First automatic trains (MP89, MP05 and MP14) enter service •
15 December 2023: Last day of driver operated services
Origins . Line 4, opened in 1908, was the last line of the original concession of the
Compagnie du chemin de fer métropolitain de Paris and the first to cross the
Seine underground (
Line 5—now
Line 6 at this point—crossed the river on the Passy bridge, later renamed the
Pont de Bir-Hakeim in 1906). The route was the subject of lengthy discussions that delayed the start of construction of the tunnel. It was originally planned as a straight line under the Rue du Louvre, under the Seine in line with the street, under the
Institut de France, along the Rue de Rennes and then the
Boulevard Raspail to the Porte d'Orleans. But as a result of the delay in the extension of the Rue de Rennes as part of
Haussmann's plan towards the Seine—which was never carried out—and the outcry from the academicians who refused categorically the line passing under the Institut de France, the route was eventually changed to cross further east through the
Place du Châtelet and the
Île de la Cité. The new route also has more coherence as a north–south route following the main traffic flows. A second modification of the route was also made: it was decided to make a temporary deviation via the major station of
Gare Montparnasse to avoid a further delay in opening the line, which was eagerly awaited. This was made necessary by the delay in building the new Boulevard Raspail between Rue de Rennes and Boulevard du Montparnasse. Once the Boulevard Raspail was completed, it was planned to take the shorter route and bypass the Gare Montparnasse. To the south of the
Vavin station the tunnel provides for the final route along the Boulevard Raspail. But the value in serving three major mainline stations by the line later led to the abandonment of this proposal.
A spectacular construction site In 1905 construction was started by the company of
Léon Chagnaud—a former mason from
Creuse (a
department with a tradition of supplying building workers in France)—and line 4 became the first to cross the Seine underground. The method used for crossing under the river is that of metal
caissons, twenty to forty meters in length mounted on the banks and sunken vertically in the river bed. The ends of the caissons were blocked and they were towed to their location before being ballasted with water and sunk in the riverbed. A chamber filled with pressurised air was built at the lower level of these caissons so that workers could excavate under the caissons. Each caisson gradually sank to its final position as the ground below it was removed. The northern stream of the
Seine required three caissons, the southern stream two caissons. The crossing of the Seine also involved the freezing of saturated ground between the station of
Saint-Michel and the Seine, under the line of the
Chemin de Fer de Paris à Orléans (now
RER line C) in 1908 and 1909. The installation of two refrigeration plants allowed the movement of brine cooled to −25 °C in dozens of tubes to stabilize the ground. The northern section was the first completed: it was opened on 21 April 1908 from
Porte de Clignancourt to
Châtelet. The southern section was opened 30 in October 1909 from
Porte d'Orleans to
Raspail. The two sections were connected on 9 January 1910. However, the line was closed to traffic a few days later in January 1910, when the level of the Seine broke its banks during the
worst flood of the century. On the morning of 24 January 1910, a significant inflow of water at the Seine crossing interrupted services between Châtelet and Vavin, although services were restored later in the day. But the inflow increased and services were again halted in the afternoon. On 26 January Châtelet station and the crossing under the river was completely flooded and slowly rose in the tunnel. On the night of 27 and 28 January, flooding reached
Réaumur – Sébastopol and eventually
Gare de l'Est: The line at its minimum was reduced to operating between Clignancourt and Gare du Nord and between Vavin and Porte d'Orleans. The fall in the level of flooding during February allowed a gradual resumption of operations, but full service was not restored to 6 April after repair of extensive damage caused to the infrastructure. During the politically turbulent 1930s, Line 4 had its own drama: on 27 July 1934, a package left in a carriage was carried into the office of its chief supervisor, located on the platform of Montparnasse. The package exploded, killing the chief supervisor and another officer and wounding four passengers. The assassins were never found. During World War II the most violent bombing Paris suffered was on the night of 20 and 21 April 1944 when the rail freight yard of la Chapelle and the main truck workshop at Rue Championnet were hit. The roof of the
Simplon station was hit by a bomb and it collapsed on the tracks and platforms. After repairs the line was brought back into service a few days later. File:Malcuit - Métropolitain de Paris - Souterrain construit sur caisson à air comprimé.JPG|Postcard explaining the construction of the crossing under the
Seine by the use of pressurised sunken
caissons File:Paris - Les travaux du Metropolitain - Foncage d un caisson.jpg|Sinking of a caisson in the narrow (southern) stream of the
Seine in 1906 File:Paris - Les travaux du Metropolitain - Foncage du caisson central.jpg|Sinking of the central caisson in the northern stream of the Seine File:Paris - Les travaux du Metropolitain place Saint-Michel.jpg|Sinking of the
Saint-Michel station File:Paris - Travaux du Metropolitain - Les fermes de la place Saint-Michel.jpg|Work sites in the Place Saint-Michel and Boulevard Saint-Andre before the sinking
The rubber tyre metro and the deviation of the line rubber-tyred trains. The RATP was satisfied by experimentation with
rubber tyres on
Line 11 beginning in 1956. It therefore decided to equip lines 1 and 4 for rubber-tyre operations, which can increase line capacity by providing better acceleration and decelerations as a result of a much superior grip. In the early 1960s these two lines were the two busiest on the network, with loads of 140% of capacity during the evening peak. However, as this change alone was insufficient to overcome this saturation, the length of stations was lengthened from , allowing the lengthening of train from five to six carriages. This work was carried out very quickly and, as early as October 1965, trains of six carriages traversed the line. On 3 October 1966, the first train composed of
MP 59 electric multiple units operated on the line. The Line 4 trains were identical to those on Line 1, being composed of four motors and two trailers per train. The line's MP 59 fleet included 556 carriages: 376 powered carriages and 180 trailers. On 17 July 1967, the last steel-wheeled train left the line to strengthen the service of others with a hundred cars built before 1914 scrapped. In February 1971, line 4 was the second network after line 11 to be equipped with semi-automatic operation, with a system known as
Grecque ("Greek"). This allowed trains to run automatically once started by the driver and stop at the next station. Since its opening the only change of the route of the line took place in early October 1977 with the deviation of the line with the relocation of the station at
Les Halles. During the excavation of the enormous
Les Halles complex the station of Les Halles was relocated about ten metres further east to allow a shorter connection to
Châtelet – Les Halles RER station. For this, three hundred and thirty meters of tunnel were built to join the old route. The changeover took place on three consecutive nights from 10 PM on Friday, 30 September 1977 to the beginning of services on Monday, 3 October. On the first night, the new track 2 was connected, on the second night, the new track 1 was built and on the last night it was connected. On 6 August 2005 at 4:42 pm, a fire on a train at Simplon due to the malfunction of a
circuit breaker caused the evacuation of two MP 59 trains with 19 people mildly affected. The fire was extinguished by fire fighters at around 6:00 pm.
Extension to Montrouge and the MP 89 Until 2013, Line 4 was one of a few lines (the others being semicircular lines 2 and 6, as well as the then new Line 14) that had never been extended beyond the "gates" of Paris. During the 1920s, a preliminary extension towards la Vache-Noire was planned but never carried out. Since that time, no other extension plan was brought up. In 2008, nearly a century after its opening, construction of a one-station extension towards began. The new station officially opened to passengers on 23 March 2013, allowing one to travel from Montrouge to Clignancourt in 30 minutes. Mairie de Montrouge is a traditional two-tracked station. In addition to the Montrouge extension, in 2011 there has been a much needed refreshing in rolling stock for Line 4, as the MP 59 trainsets were reaching the end of their useful lives. The automation of Line 1 and purchasing of new automated rolling stock (the
MP 05) allowed the RATP to replace the MP 59 with the
MP 89CC rolling stock from
Line 1. Testing of the MP 89 during overnight hours took place in 2010, with the first train (#01) to be transferred to Line 4 in April, 2011 and enter service on 23 May 2011. A second train (#44) entered service on 10 September 2011. The first MP 59 train that was retired was #6049, which was pulled from service in April, 2011. As the MP 05 rolling stock began to debut on Line 1, the pace of transferring the MP 89CC stock from Line 1 to Line 4 increased to roughly 3 trains per month. Since January 2012, the RATP kept this rate of transfer (increasing the rate to 4 trains during November and December) despite only being able to remove 2 MP 59 trainsets from service each month. During the course of 2011, the following trains were transferred from Line 1 to Line 4: #s 14, 20, 29, 30, 31, 34, 38, and 40. Train #s 03 through 25, 27 through 42, 43, 44, 48, 49, 51, and 52 were transferred during the course of 2012. #45 was transferred on 3 January 2013, marking the 47th train to be moved to Line 4. Between February and March 2013, #s 02, 46, 47, and 50 were transferred. The final MP 89CC train was #26. The last MP 59 train to be pulled from service was #6021, which was withdrawn on 21 December 2012. Though many MP 59 trains operated on Line 4 for roughly 45 years, those trains that were brought over from Line 1 during the late 1990s have circulated throughout the Metro for about 50 years.
Extension to Bagneux Following the opening of Mairie de Montrouge, plans were already in the works to further extend Line 4 another 1.8km southward. This extension consists of two stations: at the border between Montrouge and Bagneux (in Montrouge) and . Construction began in 2014, and service opened on 13 January 2022.
Automation of the line Following the implementation of full automation of
line 1, completed at the end of 2012, automation of line 4 was studied. Pierre Mongin, Chairman and CEO of
RATP, confirmed that automation would go ahead on 2 April 2013. He announced that it could be implemented from 2017 when the automatic
MP 89 and
MP 05 trains from line 14 could be transferred to line 4; line 14 would then receive the new 8-car MP 14 trains, to cope with the increase in passenger numbers expected from its extension as part of the Grand Paris project. The improvement in regularity and safety brought by automation would be increased, as on line 1, with the installation of
platform screen doors built by
Faiveley Transport, manufacturer of platform screen doors for line 14. Given the positive results of the full automation of line 1, on 10 July 2013, the STIF (now IDFM) authorised the launch of technical studies in 2013. The automation of line 4, which was estimated to cost €256 million, would be financed with €100 million from the STIF and the remainder by the RATP, the project owner. It was announced that work would start in 2014 and be completed by 2022. The financing agreement was adopted by the STIF in June 2014. Work finally began in 2016. The installation of the platform doors and the first tests of the system began in the second quarter of 2018. At that time, it was expected that the first driverless trains would be running in 2020 and the completion of automation was planned for 2022. The project was two years behind schedule: at the end of 2021, the first automatic trains were expected to run in the summer of 2022, with full automation completed by the end of 2023. The new centralised control station was put into service on 3 May 2020. The first four automatic trains began operating on 12 September 2022. Other automatic sets were added gradually to make the line fully automatic. Operation has been possible with only automatic trains since 15 December 2023. The automation of the line was inaugurated a month later on 19 January 2024.
Traffic Line 4 was once the busiest line in the Paris network, until Line 1 overtook it in 1997. From 1992 to 2004, traffic increased by 3.7%, which only places the line in ninth place in terms of growth on the network (excluding Line 14). This low growth is explained, for Line 4 itself or for the metro network as a whole, in part by significant declines in ridership when the
RER B at
Saint-Michel–Notre-Dame came into service in 1988, the
RER D in 1995 and the
RER E in 1999. The busiest stations served by the line are, in descending order (in annual traffic, all lines included): Gare du Nord (36.49 million passengers), Montparnasse - Bienvenüe (29.46 million), Gare de l'Est (15.66 million), Châtelet (12.84 million), Les Halles (12.63 million), Barbès - Rochechouart (9.14 million), Strasbourg - Saint-Denis (8.76 million). In 1998, daily traffic reached 463,974 passengers on average each working day, 361,313 on Saturdays and 209,955 on Sundays. In 2003, annual traffic reached 137,939,350 passengers, with a daily traffic of 458,148 passengers on average each working day, 374,501 on Saturdays and 241,681 on Sundays. In 2009, annual traffic was 172 million passengers, an increase of 24.5% in six years. Traffic on a normal working day reached 674,000 passengers in 2010, 676,000 in 2011 and 740,000 in 2012. ==Planned Northern Extension towards Saint-Ouen==