S21 (ZVV)
The S21 is a regional railway service of the Zürich S-Bahn of the Zürcher Verkehrsverbund. The service operates at peak hours between and over the Wettingen–Effretikon railway, supplementing the regular service, which continues west to. The S21 designation was previously used for service from Zürich to over the Thalwil–Arth-Goldau railway; this is now provided by the.Route
The service operates on weekdays during peak hours; there are a total of eight trains in each direction per day. Inbound trains in the morning and outbound trains in the evening bypass. Trains stop at the following stations:
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