Line 4 will now run from Bellevue to Rehalp via Kreuzplatz and Balgrist – and at double the frequency during peak times, as before.
The Altstetten Nord station – Sihlquai/main station section will be served by temporary tram line 51 during the construction work at Bahnhofquai.
| Partial replacement via construction line 51 until December 2026 | Line 4 route until December 2026 |
| Altstetten Nord station – Escher-Wyss-Platz – Sihlquai/main station (from there it will continue via Schaffhauserplatz and Milchbuck towards Oerlikon and Seebach) | Bahnhofstrasse/main station – Central – Bellevue – Kreuzplatz – Balgrist – Rehalp. |
After the timetable change in December 2026, line 4 will run as usual to Altstetten Nord station. It will serve the Altstetten Nord station – Escher-Wyss-Platz – Central – Bellevue – Kreuzplatz – Rehalp route.


The Bahnhofquai/HB stop is being extensively renovated and converted to make it barrier-free. It will therefore be closed for one year from 14 December 2025.