M4 (Warsaw)

The M4 line is the planned fourth line of the Warsaw Metro. It will have a length of approximately 26 km and will consist of 23 stations, linking Wilanów with Tarchomin. It will also include a new metro depot, STP Polfa.

The line will be an important element of the metro network and the overall transport system in Warsaw. According to initial findings, it is expected to be used by up to 30,000 people per hour. It will connect the districts of Białołęka, Bielany, Żoliborz, Śródmieście, Wola, Ochota, Włochy, Mokotów, and Wilanów, as well as enable interchange to M1, M2, M3, and M5 metro lines and the main public transport lines: trams, buses, and railways.

Upon its completion, M4 is planned to be the longest line in the Warsaw Metro system.

History
The line was initially announced in February 2023 by the mayor of Warsaw, Rafał Trzaskowski, in the city's plan to construct five metro lines by 2050.

On March 14, 2024, Warsaw City Council allocated 56 million PLN for pre-design works for the M4 line. On March 19, a tender for the works was issued. The pre-design works are expected to be finished by 2027.

Construction of the M4 line is expected to take place at the same time as the M3 line, starting somewhere in the 2030s.

Stations
The initial station plan for the line was shared on the Warsaw Metro website: