MGB ABDeh 4/8 (Komet)

Updated: August 2026 – ABDeh 4/8 isn’t a number you have to look up, it’s a sentence you can read: first and second class, luggage compartment, electric, rack drive, four of eight axles powered. This page takes the designation apart, shows you how to spot the Matterhorn Gotthard Bahn railcar in the field, and gives photo tips for metre-gauge mountain services.

What is the MGB ABDeh 4/8?

The MGB ABDeh 4/8 is an electric rack railway multiple unit in two-car formation for the metre-gauge mountain services of the Matterhorn Gotthard Bahn. It carries first and second class as well as a luggage, or rather multi-purpose, compartment, and four of its eight axles are powered. Day to day it goes by the nickname Komet.

This combination is typical of Swiss mountain railways that aren’t pure excursion lines but handle genuine traffic: they need rack drive for the steep sections, yet also classes, luggage space and the fittings you’d expect from a regular passenger train. That’s exactly what the designation says – and that’s exactly why it’s worth reading the Swiss system rather than googling it.

The designation, letter by letter

If you want a systematic way of tackling unfamiliar vehicles, the fixed order of steps in the guide to identifying classes helps. The internationally valid vehicle number carrying the Swiss country code 85 is explained in the article on reading the UIC number.

Identifying it in the field: the track first

On mountain railways, the fastest way to identify a vehicle isn’t looking at the vehicle at all. Look at the track – it tells you the gauge and the drive principle before the first train even arrives.

Observation	What you see	What it means
Centre of the track	Rack rail	Rack railway, an h appears in the name
Gauge	Narrower than standard gauge	Metre gauge, typical of Swiss mountain railways
Vehicle length	Two-car unit, eight axles	Fits a 4/8 designation
Markings	MGB	Narrows down the railway company
Designation	ABDeh 4/8	Unambiguous identification including the luggage compartment
Doors and compartments	A recognisable multi-purpose area	Confirms the D in the name

The route via the track works even if you don’t know the railway. A rack rail rules out pure adhesion vehicles, metre gauge rules out standard-gauge vehicles – and what’s left is a manageable group of vehicle types. Conversely: where there’s no rack rail, as on the Bernina line down to Tirano, pure adhesion stock runs instead.

Photo tips for metre gauge in the mountains

Narrow-gauge vehicles in the mountains are a rewarding subject – provided you use the surroundings rather than cropping them out. How much the surroundings can carry a shot is shown by the Landwasser Viaduct near Filisur.

The most important rule stays the same whatever the subject: tracks, the rack rail and operational installations are off limits. The fact that a mountain train runs slowly changes nothing about that – and out in the terrain there’s also poor visibility and private land to consider. The ground rules are set out in the article on keeping a safe distance from the track.

One thought that saves a lot of time with narrow-gauge railways: the route determines the vehicle, not the other way round. Gauge, gradient, curve radii and whether there’s a rack rail decide what can run there at all. So anyone visiting an unfamiliar railway for the first time can narrow down what type of vehicle to expect before the first train even shows up.

That also explains why narrow-gauge vehicles so rarely move between railways. A standard-gauge multiple unit can in principle be used anywhere in the network where it’s cleared to run. A metre-gauge rack vehicle, by contrast, is tied to its own network: different gauge, different rack-rail design, different overhead line. That’s why the metre-gauge railways of Graubünden run completely different stock – such as on the Albula line near Bergün. Behind that network is the Rhaetian Railway, whose vehicles are just as tied to it and can’t move to another railway either. For spotters that means two things: the vehicles are fixed in place and therefore plannable, but you have to travel to them. A sighting you miss doesn’t happen to turn up somewhere else by chance.

Common mix-ups

The closest relatives in the MGB fleet are the three-car ABeh 8/12 “Orion” – same drive type, different fraction, no D in the name – and on the locomotive side the HGe 4/4. At a different railway, but named to the same system, runs the Bhe 4/8 on the Gornergrat, which carries only second class.

Verdict

The ABDeh 4/8 is a prime example of just how much information sits in a Swiss vehicle designation. Five letters and a fraction describe classes, luggage compartment, power source, drive principle and axle ratio – fully, and without having to look anything up. In the field, a glance at the track gets you half the identification, and the markings supply the rest.