Line 15's route bears a strong resemblance to the
Arc Express proposal initially presented by
RATP in 2006. It was subsequently incorporated as the "Red Line" within the Grand Paris public transportation network project, introduced by then-President
Nicolas Sarkozy in 2009. The line received its current designation in 2013 when Prime Minister
Jean-Marc Ayrault announced the "New Grand Paris" project. The initial 2013 government plan announced groundbreaking for the southern section in early 2015, groundbreaking for the western and eastern segments in 2020, opening of the southern section in 2024 (later revised to 2025, then to summer 2026, then to late 2026, now to April 2027 (later revised to 2031
Construction Line 15 will be constructed in two phases : • The line's southern section, connecting
Pont de Sèvres and
Noisy–Champs, is scheduled to open in April 2027. • The complete line, encompassing western (Pont de Sèvres to ) and eastern sections (Saint-Denis–Pleyel to ), is projected for completion and inauguration in 2031.
Line 15 South The southern section (Pont de Sèvres to Noisy–Champs) encompasses 16 stations, two maintenance depots and stretches . The construction of this section has encountered delays, missing the targeted opening before the
2024 Summer Olympics. This section of the line is estimated to have cost around . A significant engineering milestone was the completion of the
Villejuif–Gustave Roussy station. While the station's upper levels began serving the Line 14 extension in 2024, its Line 15 platforms are located at a depth of -48.8 meters (level -9). It is the second-deepest station on the network, surpassed only by
Saint-Maur–Créteil, and was designed as a vertical 'open cylinder' to allow natural light to reach the lower mezzanine levels.
Line 15 East and West under construction The northern section comprises two segments: west ( to ) and east (Saint-Denis–Pleyel to ). Upon completion, now scheduled for 2031, these sections will connect with the southern section to form the complete orbital route. The eastern section's initial cost estimate of €3.77 billion has been revised upwards to €5.65 billion (). While major construction contracts for the line itself haven't been awarded yet, preparatory work is underway at Saint-Denis–Pleyel and Champigny Centre stations, which are being built for other lines but will include platforms for Line 15. == Rolling stock ==