Südostbahn

The rail network of the Südostbahn (SOB) consists of that formerly owned by BT in northeast Switzerland (between Lake Constance and Toggenburg):

• Romanshorn–St. Gallen St. Fiden line,
• St. Gallen–Herisau–Degersheim–Wattwil line, and
• (Wattwil–)Ebnat-Kappel–Krummenau–Nesslau-Neu Sankt Johann line,

and that previously owned by the original SOB located predominantly in Central Switzerland:

• Rapperswil–Pfäffikon SZ line,
• Pfäffikon SZ–Freienbach SOB–Wollerau–Samstagern–Schindellegi-Feusisberg–Biberbrugg–Altmatt–Rothenthurm–Biberegg–Sattel-Aegeri–Steinerberg–Arth-Goldau line, and
• Einsiedeln–Biberbrugg–Schindellegi-Feusisberg–Samstagern–Wädenswil line.

Since 2006, SOB also owns Wattwil station and the railway from Wattwil to Ebnat-Kappel, which until then belonged to SBB CFF FFS. The railway stations of Romanshorn, St. Gallen, and Pfäffikon SZ, and the railway tracks between St. Gallen St. Fiden–St. Gallen, Wattwil (except railway station)–Rapperswil, and Arth-Goldau–Luzern are owned by Swiss Federal Railways, but are used by SOB for its services.

In total, the SOB network measures 128.9 kilometres (80.1 miles), and comprises the following lines:

• Romanshorn – St. Gallen St. Fiden (19.1 kilometres (11.9 miles))
• St. Gallen – Wattwil – Nesslau-Neu St. Johann (44.5 kilometres (27.7 miles))
• Rapperswil – Pfäffikon SZ (Seedamm) (4 kilometres (2.5 miles))
• Pfäffikon SZ – Arth-Goldau (34.6 kilometres (21.5 miles), including 6.1 kilometres (3.8 miles) common with Wädenswil–Einsiedeln)
• Wädenswil – Einsiedeln (16.7 kilometres (10.4 miles))

The adhesion railway network spreads over mountainous terrain, with a maximum slope of 50‰ (5 %) between Wädenswil/Pfäffikon SZ and Biberbrugg, and between Rothenthurm and Arth-Goldau. The lowest altitude on the SOB network is found at Romanshorn (399 metres (1,309 ft) a.s.l.), and the highest at Biberegg (933 metres (3,061 ft) a.s.l.), between Rothenthurm and Sattel-Aegeri. The highest elevation on the section between Nesslau-Neu St. Johann and St. Gallen is reached near Degersheim (798.7 metres (2,620 ft) a.s.l.).

The network is mostly a single-track railway, with intermittent double-tracks (9.84 kilometres (6.11 mi) in total) present in sections where trains cross regularly. The entire network is electrified since 1939.

The direct connection from Bodensee via Zürichsee towards Vierwaldstättersee, which follows the Alpine foothills, was achieved by numerous civil engineering works. These consist of a series of viaducts and tunnels. Engineering structures account for one eighth of the total SOB rail network.[2] They comprise:

• 177 bridges spanning a total of 4.2 kilometres (2.6 miles), and
• 19 tunnels through 8.5 kilometres (5.3 miles) of mountains.

One of the viaducts, the 99 metres (325 ft) high and 365 metres (1,198 ft) long Sitter Viaduct (SOB) near St. Gallen Haggen, is the highest railway bridge in Switzerland. It is also the longest bridge on the SOB network and was built between 1908 and 1910. Other notable viaducts are the Glatttal Viaduct (296 metres (971 ft) long, 34 metres (112 ft) high) near Herisau station, and the Wissbach Viaduct (289.5 metres (950 ft) long, 63 metres (207 ft) high) between Degersheim and Schachen. Many bridges of the SOB network were constructed by BT.

The longest tunnel on the SOB network is the 3.5 kilometres (2.2 mi) long Wasserfluh Tunnel between Brunnadern-Neckertal and Lichtensteig, with 10.4‰ grades. The tunnel was constructed between 1905 and 1910. The second longest tunnel is the Bruggwald Tunnel between St. Gallen St. Fiden and Wittenbach, having a length of 1.7 kilometres (1.1 mi) and a slope of 12‰. It was built between 1907 and 1910. Most tunnels of the SOB network belonged to BT previously. Note that the 8.6 kilometres (5.3 mi) long Ricken Tunnel on the Uznach–Wattwil line, used by the SOB operated Voralpen Express and S4 service of St. Gallen S-Bahn, belongs to Swiss Federal Railways (SBB CFF FFS).

In the 1990s, the former Südostbahn (SOB) ordered four two-piece NPZ (Neuer Pendelzug; English: "new commuter train") sets (RBDe 566 + ABt), which were delivered from the first production series in 1995, bearing numbers RBDe 566 400-403. Initially, the SOB opted not to convert any intermediate cars for use with these trainsets. Thus, the SOB DVTs differed from those of the SBB CFF FFS by the addition of a first class compartment. The motor coaches of the NPZ sets, however, were identical to those of SBB CFF FFS. The SOB later converted several intermediate cars to elongate their trainsets (three-/four-car sets).

The NPZ first class control cars (ABt) existed for the two types of RBDe 566 that SOB owned at that time (RBDe 566 071-076 ex BT and RBDe 566 077-080 ex original SOB of the type also used by SBB CFF FFS). Until 2019, nine second class control cars (BDt) were used for the Voralpen-Express sets with Re 456, Re 446 or Re 420 (the latter occasionally leased from SBB-CFF-FFS) locomotives. After the merger of the original SOB with BT, the four NPZ sets were repainted in 2003 in the livery of the new SOB, with the sides of the vehicles painted light and dark gray, and the nose and border between side and roof painted red. They operated throughout the SOB network as RBDe 566 077-080.

The NPZ sets were later replaced by Stadler FLIRT EMUs (four-car-sets), delivered between 2007 and 2013 (RABe 526 041-526 063). The latter were painted in the most recent SOB livery: silver, with red window band, and light gray doors. Additional FLIRT-III four-car-sets were delivered between 2019 and 2021 (RABe 526 001-526 006). The FLIRT/FLIRT-III sets operate as S-Bahn service, but also as extension units during peak-hours on InterRegio lines, i.e., for the named trains Voralpen-Express/Treno Gottardo/Aare Linth, for which new copper-red painted Traverso eight-car EMU sets (RABe 526 101/201-526 117/217) started operations between 2019 and 2021. Some of the FLIRT/FLIRT-III sets are named after mountain peaks along SOB operated lines. The names are indicated near the ends of the trainsets.

Wikimedia Commons has media related to Südostbahn.

• Official website (in German)
• Voralpen-Express website (in English)
• Treno Gottardo website (in English)
• Aare Linth website (in English)