[1] A westward extension was progressively put into service, first to Pereire on 23 May 1910 and later to Porte de Champerret on 15 February 1911.

[2] On 14 June 1901 the Council of Paris announced its wish for a study regarding the construction of a network to complement the first lines; the goal was to leave no point in the city more than 400 metres (0.25 mi) away from a métro station.

It was constructed under the avenue Gambetta to Porte Lilas, where a turnaround loop was installed under the city walls.

As a result, the tunnel was built in a layer of gypsum, very deep underground; stations were contained in a reinforced vault, with elevators linking the platforms to the surface.

This variant measured 10.85 metres (35 ft 7 in) in length and consisted of one train powered by two motors.

[4] The shuttle ceased operation on 3 September 1939 as part of the World War II service cutbacks.

As the passenger traffic to Bagnolet was expected to be much greater than that to Porte des Lilas, the construction of a fork was ruled out.

To accommodate these changes, Gambetta, which at the time consisted of only two half-stations[clarification needed], underwent major alteration.

The line follows the avenue Gambetta in a north-easterly direction, following a nearly straight route to pass through the two deep stations of Pelleport and Saint-Fargeau, before reaching its terminus at Porte des Lilas.

The line ends with a turnaround loop, with one of the two tracks allowing for trains to be transferred to the voie navette.

[10] The architect Charles Plumet was charged with designing the outside entrances to the Pelleport, Saint-Fargeau, and Porte des Lilas stations.

A shuttle operated along these tracks until it was closed shortly before the start of World War II.

Repairs and regular maintenance (e.g. of batteries, electrical wiring, and paint) are carried out at the depot at Choisy, along with the rest of the Paris rail network.

Opened in 1931, it is situated in the 13th arrondissement, close to the boulevard périphérique and accessible via a branch off line 7.

[6] Between 1972 and July 1981, the Sprague-Thomson variant was used, but this was then replaced with MF 67trains of only three cars (because of the low passenger volumes), which still run on the line today.

Station agents are responsible for selling tickets, ensuring that passengers have not entered the métro illegally (i.e. preventing fare evasion), managing the stations, and ensuring the proper installation of instructional signs and other fixtures according to service needs.

Fares and subscription prices are regulated by the government and in fact their revenues do not cover the entire operating costs of the network.

The organisation defines the general conditions of operation including the duration and frequency of services.

The operational budget is guaranteed by an annual subsidy provided to the general transportation network of the region; this subsidy is funded by a tax (the versement transport (VT), which is imposed on all companies in the region that employ more than nine people, as well as other public funds.