SWITZERLAND: For decades Swiss operator Montreux-Oberland-Bernois has dreamed of running through trains on its Golden Pass route from Montreux on Lac Léman to Interlaken and Luzern. Already world famous because of its stunning scenery, the trip requires passengers to change trains at Zweisimmen and Interlaken Ost because the central part of the 189 km route is standard gauge whereas the two outer legs are metre gauge.

Proposals for through trains have until now focused on laying a third rail between Zweisimmen and Interlaken, but studies completed in 2006 found the SFr260m cost to be prohibitive, not least because of the need to separate traffic flows where the route crosses the busy Lötschberg main line at Spiez.

Now MOB has come up with a cheaper alternative that has the potential to be used on other routes interrupted by a break of gauge, such as Zürich – St Moritz. The answer is an ingenious bogie design able to run on 1 000 mm or 1 435 mm gauge track which was developed by MOB's Chief Engineer Jean-Marc Forclaz.

Unveiled in October by MOB Director Richard Kummrow, the patented bogie design, which would be fitted to MOB's existing loco-hauled panoramic stock, features a central cross-member with a pivot and a single airbag for the secondary suspension. The cross-member is linked to a pair of interlocking triangular half-frames (Fig 1) which support the individual wheels. The two wheels on each side are attached to a longitudinal section forming one side of the triangular half-frame, and the opposite point of the triangle passes through the longitudinal section of the other half-frame, culminating in a long pin along which the other half-frame can slide laterally. The sliding movement is only possible once the frames are unlocked by the release of vertical elements attached to the ends of the cross-member.

As the train passes through a gauge-changing installation, the cross-member is raised and the weight of the vehicle is supported by rails on the side of the track. The triangular half-frames carrying the wheels are unlocked and are then free to move in or out, guided by vertical pins that run inside channels in the gauge-changer. As the train passes through, the cross-members are also lifted or lowered by 200 mm, so adjusting the height of the vehicles to the different platform heights at metre gauge and standard gauge stations.

Funding for the initial phase of the scheme has been secured from the federal government and the three cantons along the route. Bogie specialist Prose of Winterthur is to build a prototype by 2010, and if this is successful, an order for a production build of gauge-changing bogies would be placed in 2011. This would allow the introduction of through trains between Montreux and Interlaken Ost around 2013-14. Further development is required before the trains could reach Luzern, as the bogies would have to be equipped with rack apparatus for use on the Zentralbahn's Brünig route.

MOB is contemplating a two-hourly through service, which would require additional coaches to be purchased at a cost of SFr15m. The cost of the gauge-changing bogie development is put at SFr29m, which MOB and its partner railways hope would be amply repaid once the through trains start to run.