Currently under construction, the line will provide a new orbital route through the suburbs of Paris, servicing the departments of Hauts-de-Seine, Val-de-Marne and Seine-Saint-Denis.

[4] The route for Line 15 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 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 southern section (Pont de Sèvres to Noisy–Champs) encompasses 16 stations, two maintenance depots and stretches 33 kilometres (21 mi).