This is an additional line for the proposed urban-regional metro network. It would be a semicircular line, using the existing line 20, from Warszawa Zachodnia station, through Warszawa Gdańska station, to Rembertów on line 2.
The S-Bahn line would start at Warszawa Zachodnia, possibly at the existing Warszawa Wola station. The existing line would be 4-tracked, to provide sufficient capacity for other services. There are stations at Warszawa Kasprzaka and Warszawa Koło (interchange with the future metro line 2). One or two new stations are possible, on the section to Warszawa Gdańska. After that station, the line crosses the river Vistula (Wisła), to Warszawa Zoo station. From there, trains would run over the upgraded link line to the Rembertów line, with a new station at Aleja Solidarności.
At its western end, the line could be connected to line 8, north of Warszawa Służewiec station, by a tunnel. In that case, the most logical option is a service to Warsaw Airport, over a short new line. Two possible alignments for that line are shown.
This proposed S-Bahn line connects well with services through Rembertów, and the proposed north-south right bank S-Bahn line. but not with the line to Zielonka, or to Warszawa Wschodnia station. An alternative is to build a light metro from Warszawa Zachodnia, alongside line 20, which would then turn south into Warszawa Wschodnia, alongside an existing curve. This option would allow more intermediate stations. The rail line itself would then have only one station, at Warszawa Gdańska, for regional and long-distance services.