Berlin: S-Bahn S15 on the way, soon.
Above: Berlin S-Bahn S15 icon, from Wikimedia, by users F84 (original) and Minoa (rework).
For me, living memories of countless times in Berlin since 2002 include public transport with her U-Bahn and S-Bahn trains and routes. Like many, I never want that S-Bahn three-tone door-closing signal to go away, but that only comes with the older Baureihe 481-482 vehicles used for the trains, which will go away with the requirement to comply with European Union regulations.
On my first visit in 2002, I immediately asked: why isn’t there a U-Bahn connection or an S-Bahn connection with the shiny Berlin central train station? The U5 finally answered the first question in 2020, whereas the S-Bahn connection is coming up in 2026. The S-Bahn line provisionally labelled S15 is part of the larger long-term S21 project to connect the north and south parts of the S-Bahn Ring with the central station, and helping to alleviate traffic along the existing north-south S1-S2 route. In late-2025, news came out with a scheduled opening: on 28 March 2026, the S15 will open for public service between Gesundbrunnen and Hauptbahnhof via Wedding, although I’m unsure why the latest map update doesn’t mark S15 service between Westhafen and Hauptbahnhof; see below.
Announcement items in German: RBB24 — Entwicklungsstadt.
In this coming summer of 2026, I’m looking forward to seeing how this works out.