GoldenPass Express

The GoldenPass Express is a luxury railway service that operates between Montreux, on Lake Geneva, and Interlaken, in the Bernese Oberland, in Switzerland. The train is owned and operated jointly by the Montreux Oberland Bernois Railway (MOB) and BLS AG (BLS). As such, it uses the MOB's gauge line between Montreux and Zweisimmen. In Zweisimmen, the train cars change gauges in order to operate on BLS' gauge lines from Zweisimmen to Spiez and then from Spiez to Interlaken. The automated gauge conversion, which adjusts both the track gauge and the height of the car body (to account for differences in platform heights), is believed to the first of its kind in the world.

Route
The western terminus of the train is Montreux, on the shore of Lake Geneva in the canton of Vaud. Montreux is the terminus of the Montreux–Lenk im Simmental line's gauge Montreux–Lenk im Simmental line and is shared with the  gauge Simplon line of Swiss Federal Railways. The train then climbs into the Bernese Alps, facing a maximum grade of $23 per mille$ before arriving at the first intermediate stop of Montbovon, 22.1 km and 48 minutes from Montreux.

From Montbovon the train continues through the Alps, following the course of the river Saane/Sarine to Château-d'Œx and Gstaad, the latter a famous holiday destination. The train encounters a maximum grade of $30 per mille$ as it continues climbing while traveling east. The train continues climbing, rising more than 1260 m above sea level near Saanenmöser before arriving in Zweisimmen, two hours and four minutes and 62.4 km from Montreux.

In Zweisimmen, the train goes through the gauge-changing operation and a locomotive swap, with a BLS AG locomotive handling the train between Zweisimmen and Interlaken Ost. In addition to converting between standard gauge and metre gauge, the platform height rises from 350 mm to 550 mm.

The BLS line from Zweisimmen to Spiez through the Simmental is comparatively flat, and the train covers the 34.9 km to Spiez in 44 minutes. From Spiez, the train uses the Lake Thun railway line, which rounds the southern edge of Lake Thun to Interlaken Ost, where a planned connection with the Zentralbahn's Luzern-Interlaken Express to Lucerne is available.

History
The GoldenPass Express began operation on 11 December 2022, the date of the timetable change, with a single daily round-trip between Montreux and Interlaken. The two operators MOB and BLS plan to increase the frequency to four round-trips on 11 June 2023. This gradual increase is to match the lower demand caused by the global pandemic.

From 20 March 2023, The GoldenPass Express was limited to the meter gauge section of the line between Zweisimmen and Montreux, due to increased wear on railway infrastructure caused by the gauge changing train. The issue was later resolved by adjusting the wheel spacing on the standard gauge sections and through running services resumed on 11 June 2023 with one daily round trip. The service was set to expand to four daily round trips until end of July 2023 as more rolling stock was modified.