Route

The Sihltal line shares a common terminus with the Uetliberg line, utilising a dedicated underground island platform (Zürich HB SZU) at Zürich Hauptbahnhof station. There is no rail connection to the rest of the station, but the platform is served by the same complex of pedestrian subways and subterranean shopping malls that link the station's other platforms.^[2]

From Hauptbahnhof to Zürich Giesshübel station the two lines share a common twin-track line, initially in tunnel, partly running along and under the Sihl river. The current Selnau station is located in this under-river tunnel section.^[2]

The two lines diverge at Giesshübel station, which is only served by trains on the Sihltal line. Also located here is a junction with the freight only branch to Zürich Wiedikon station on the Swiss Federal Railways' Lake Zürich left bank line. The next stop on the line is Zürich Saalsporthalle-Sihlcity station, which is adjacent to the large Sihlcity shopping mall, with direct access to the platforms from the mall. Further suburban stations follow at Zürich Brunau, Zürich Manegg and Zürich Leimbach.^[2]

Leaving the city of Zürich behind, the line closely follows the river Sihl, serving the stations of Sood-Oberleimbach, Adliswil and Sihlau in the municipality of Adliswil. At Adliswil, a short walk provides an interchange to the Adliswil-Felsenegg cable car, which rises to the summit of Felsenegg.

Beyond Adliswil, the stations of Wildpark-Höfli, Langnau-Gattikon and Sihlwald are served, although many trains terminate at Langnau-Gattikon. Beyond Sihlwald, the line continues to a junction with the Swiss Federal Railways' Thalwil–Arth-Goldau railway at Sihlbrugg station, although this section of line does not carry a regular passenger service.^[2]

Services

• S4 Zürich HB – Adliswil – Langnau-Gattikon ( – Sihlwald )
  Hourly trains operate between Langnau-Gattikon and Sihlwald.

The passenger services on the line now forms part of the Zürich S-Bahn, branded as the S4. Trains usually run every 20 minutes outside peak periods, and every 10 minutes during peak periods. Most trains terminate at Langnau-Gattikon station, with only one train per hour continuing to Sihlwald station. Standard Zürcher Verkehrsverbund (ZVV) zonal fare tariffs apply to the line.^[3][13]

The night service (SN4) of the S4 line, operating on weekends after midnight, runs between Zürich Hauptbahnhof and Langnau-Gattikon.

The Zürcher Museums-Bahn (ZMB) operates occasional heritage railway services over the Sihltal line. On the last Sunday of every month from April to October, a steam service is operated from Zürich Wiedikon station to Sihlbrugg station. The ZMB preserves a selection of former Sihltal line rolling stock, including two early steam locomotives, and a railcar and a locomotive built for the original electrification.^[14]

Infrastructure

The Sihltal line is constructed to standard gauge and uses overhead lines for electrification. Both it and the Uetliberg line, with which it shares right-of-way between Zürich HB SZU and Zürich Giesshübel, are electrified at 15 kV AC.^[15]

Prior to August 2022 the Uetliberg line used 1200 V DC. To allow both lines to operate over the shared section, the Uetliberg line used an overhead line offset from the centre of the track, and its cars were equipped with specially designed pantographs to collect from this.^[16]

Rolling stock

Passenger services on the Sihltal line are operated with a mixture of single and double deck cars, sometimes with examples of both types in the same train. Traction is provided by electric locomotives, which operate their trains in push-pull mode with a driving car at the other end of the train. Six new multiple unit trains have been ordered to enter service in 2013, equipped for dual voltage operation so as to operate on both the Uetliberg and Sihltal lines.^[17]

As of 2019^[update], service continues to be provided by Class 450 and 456 [de] electric locomotives in push-pull operation, with 3–4 single- and double-decker coaches. Depending on the configuration, each train has between 351 and 448 seats.^[18]