Proposed here is an S-Bahn line across southern Warsaw, as part of the proposed urban-regional metro network. It is a more tentative proposal than the proposed north ring line, and much of it is on completely new alignment. It is a purely tangential line, a semicircle about 5 to 7 kilometres from the city centre.
The line would start at Warszawa Włochy Station, on line 1 to Katowice and line 3 to Berlin. Line 3 diverges from Line 1 here, using a connecting line through Ursus Północny to Warszawa_Gołąbki station on the original Berlin line.
Following an existing curve, the new line would then join rail line 8, from Warszawa Zachodnia Station toward Radom. At Aleje Jerozolimskie station there would be interchange with the light-rail line WKD
Near Warszawa Rakowiec station, the new alignment would begin, descending into tunnel. That could be east or west of the crossing with Aleja Żwirki i Wigury (the main road to the airport), some demolition is inevitable here. There would be a station here, an interchange with a possible north-south urban-regional line.
East of Żwirki i Wigury, the tunnel would follow ul. Woronicza. At Wierzbno metro station, the new line would connect with Metro Line 1. It would then cross Ulica Puławska and Park Arkadia, toward the road junction (DK7 / DW724) at Czerniaków. From there it would follow, probably on surface, the Trasa Siekierkowska, a section of the planned ring road ( Obwodnica Etapowa Warszawy, OEW). It would cross the Vistula next to the Siekierkowski Bridge.
The line could terminate in a tunnel section at Warszawa Gocławek station, but it would be more logical to extend it, parallel to the planned OEW road, to Rembertów station. This last section is an alternative to the proposed south tangent metro. From Rembertów, trains could use the existing link line 449 to Zielonka on Line 21.