The Appenzellerbahn and Santisbahn merged in 1947, retaining the Appenzellerbahn (AB) identity. The St. Gallen–Gais–Appenzell-Bahn and Altstätten-Gais-Bahn merged in 1948, under the name St. Gallen–Gais–Appenzell–Altstätten-Bahn (SGA).[2]
The Appenzeller Bahnen company was formed in 1988, with the merger of the Appenzellerbahn and the St. Gallen–Gais–Appenzell–Altstätten-Bahn. In 2006, the Appenzeller Bahnen company merged with the Rorschach–Heiden-Bergbahn, the Rheineck–Walzenhausen-Bergbahn and the Trogenerbahn companies. In legal terms, this merger took the form of the Appenzeller Bahnen company acquiring the other companies.[2]
The St. Gallen–Gais–Appenzell, Gossau–Appenzell–Wasserauen and Altstätten–Gais lines form a connected network of 1,000 mm or 3 ft 3+3⁄8 inmetre gauge lines, all electrified at 1500
VDC. Until 2018, the St. Gallen–Trogen line was also of metre gauge, but ran independently.
From 2016 to 2018, the Appenzellerbahnen undertook
a large construction project to connect the Appenzell-St. Gallen and St. Gallen-Trogen lines. The three points of incompatibility were electrification (the St. Gallen-Trogen line was 1000 V DC with a brief stretch at 600 V DC shared with the
St. Gallen trolleybus system), different (but physically adjacent) termini in St. Gallen, and maximal grades (the rack railway approach to St. Gallen from Appenzell was too steep for adhesion-based St. Gallen-Trogen rolling stock). So the new project re-electrified the St. Gallen-Trogen line at 1500 V DC and constructed a new tunnel through St. Gallen. The old alignment through St. Gallen closed in April 2018, and the system began through-running in October of the same year.[7][8]
The Rheineck–Walzenhausen and Rorschach–Heiden lines are geographically separate from the rest of the network, and are of respectively
1,200 mm (3 ft 11+1⁄4 in) and
standard (1,435 mm or 4 ft 8+1⁄2 in) gauges. The Altstaetten–Gais, Rheineck–Walzenhausen and Rorschach–Heiden lines all have
rack railway sections, whilst the Gossau–Appenzell–Wasserauen and Appenzell–St. Gallen–Trogen lines are
adhesion only.[5][6] Frauenfeld-Wil was cooperating closely, but legally distinct from 2003. It is not connected by tracks. 2021 they were taken over.
The company also operates a bus service from
Teufen, on the St. Gallen–Gais–Appenzell line, to
Speicher, on the St. Gallen–Trogen line. Night bus services are operated over the routes of the St. Gallen–Gais–Appenzell and St. Gallen–Trogen lines.[5]
As of December 2023[update], Appenzell Railways (AB) operates eight regional train services that run on its own railway network. Trains operate as
S-Bahn services (numbered 15, 20‒26 with "S" prefix) for
St. Gallen S-Bahn. In addition, AB also operate bus line 190.[9]
Operates over the metre (3 ft 3+3⁄8 in) gauge
Appenzell–St. Gallen–Trogen line. Rush-hour service, calls between Gais and St. Gallen only at Bühler, Teufen AR and Niederteufen
^Thomas Baumgartner, Lukas Regli: Die Bedeutung der Durchmesserlinie Appenzell – St. Gallen – Trogen für die Appenzeller Bahnen (in German). In: Schweizer Eisenbahn-Revue. No. 11/2013. Minirex,
ISSN1022-7113, pp. 604–606.