Key takeaways
- The Class 4110 is a double-deck multiple unit of the Stadler KISS type, used in Austrian long-distance service.
- The leading 4 of the class number denotes electric railcars and multiple units in Austria.
- Double-deck means capacity: two passenger levels per carriage at the same train length.
- Multiple unit, not a loco-hauled train: there's no separate locomotive, the traction is distributed through the formation.
- Operators and deployments change – check the current status before a targeted trip.
Contents
Fact file
| Vehicle type | Double-deck electric multiple unit for long-distance service |
|---|---|
| Manufacturer's designation | Stadler KISS |
| Designation system | Four-digit class number – the leading 4 denotes electric railcars and multiple units |
| Build | Articulated train with shared bogies between the carriages |
| Passenger levels | Two levels per carriage, boarding at an intermediate level |
| Electrification system | 15 kV / 16.7 Hz AC |
| Classic field of use | Long-distance service on the Westbahn line between Vienna and Salzburg |
Identifying features
Is this really the class in front of you?
- Double-deck carriage bodies with two rows of windows one above the other
- Fixed multiple-unit formation with no separate locomotive at the front
- Doors at an intermediate level between the lower and upper deck
- Shared bogies at the carriage gangways instead of two bogies per carriage
- Four-digit class marking, starting with 4110
Updated: August 2026 – Two rows of windows one above the other, no locomotive front, a continuous formation: the Class 4110 stands for double-deck multiple units of the Stadler KISS type in Austrian long-distance service. This page shows you how to identify it, what the class number reveals, and why double-deck construction is a very specific operational answer.
Spotted a multiple unit? Don't forget the number.
With multiple units, only the vehicle number tells one formation apart from the next – logged instantly in Traintrack.
What’s behind the Class 4110?
The Class 4110 denotes a double-deck electric multiple unit of the Stadler KISS type, used in Austrian long-distance service. It runs as a fixed formation: the traction is distributed through the train, and there’s no separate locomotive.
Its classic field of use is the Westbahn line between Vienna and Salzburg – one of the busiest routes in the country. That’s exactly where double-deck construction shows its strength: more seats at the same train length. WESTbahn runs on this route as an open-access operator with vehicles of this type. Which vehicles run for which company at any given time has, however, shifted several times in Austria. Treat this assignment as changeable and check the current status rather than relying on older overviews.
What the class number 4110 reveals
The Austrian system is especially useful here. Traction units carry the word Reihe (class) plus a four-digit number, whose first digit encodes the vehicle type:
- 1xxx – electric locomotive
- 2xxx – diesel locomotive
- 4xxx – electric railcar or multiple unit
- 5xxx – diesel railcar
A 4110 is therefore already classified as an electric multiple unit from the number alone – before you’ve even seen the vehicle. The same logic explains why the Class 4024 and the Classes 4744 and 4746 are also multiple units, while 1xxx numbers always denote locomotives. How to turn this system into a practical identification sequence is described in the guide to identifying classes.
Identifying a KISS double-deck train
Count the rows of windows
Two rows of windows one above the other mean double-deck. This is the most striking feature and works from a great distance.
Check the front of the train
A continuously styled front end with no separate locomotive points to a multiple unit. With a loco-hauled train, a standalone locomotive with its own marking stands at the front.
Look at where the doors are
The entrances sit at an intermediate level between the lower and upper deck, with stairs in both directions – typical of double-deck construction.
Locate the bogies
In an articulated train, the bogies sit under the gangways, shared by two neighbouring carriages – not in pairs under each carriage end.
Double-deck isn't always the same thing
Double-deck vehicles come in two very different forms: as carriages hauled by a locomotive, and as a multiple unit that runs under its own power. A glance at the front of the train settles in a second which variant you're looking at.
Why double-deck: the operational logic
Double-deck vehicles aren’t a design choice, they’re an answer to hard constraints.
| Constraint | Single-deck train | Double-deck train |
|---|---|---|
| Limited platform length | seats can only be increased via train length | more seats at the same length |
| Dense timetable | additional trains needed | more capacity per path |
| Passenger exchange | fast, short dwell times | slower, because of two levels |
| View for passengers | uniform | upper deck noticeably elevated |
| Photographic effect | flat silhouette | tall, massive carriage body |
The last point matters for spotters: a double-deck train looks noticeably more massive in photos and needs more frame height than a single-deck multiple unit. Anyone shooting from their usual position can easily clip the roof.
What's running on the Westbahn line right now?
Live-reported sightings show you which vehicles are currently out and about – before you set off.
Placement within rail operations
Several kinds of service meet on the Westbahn line: classic long-distance trains, fast multiple units and local services. For observation that’s an advantage, because you see very different vehicles from a single spot.
- Long-distance service in multiple-unit form. Double-deck multiple units cover services here for which loco-hauled sets are used elsewhere.
- Comparison with the Railjet. The Railjet runs as a loco-hauled push-pull train – a revealing direct contrast to a genuine multiple unit.
- Local services in the same corridor. Regional electric multiple units share the route, which further increases the variety of vehicles.
The train number helps match the services correctly. How train categories and number ranges relate, and what you can read from them, is explained in the article on decoding train numbers.
Services and operators change
Which companies run which vehicles on this route has changed several times in the past and can shift further. Check the current status before every targeted trip rather than relying on older information.
Spotting and photographing double-deck multiple units
Double-deck trains impose different requirements than loco-hauled trains – above all on your framing.
- Allow for more frame height. The carriage body is noticeably taller. Keeping your usual framing loses the roof or clips the front.
- Emphasise the front end rather than a locomotive. With a multiple unit, the styled front end is the vehicle’s face. A three-quarter view of around 30 to 45 degrees shows both the front and the side at once.
- Make deliberate use of the length. A continuous formation looks more impressive from a shallower angle than head-on – the train length becomes a compositional element.
- Use dwell times at the platform. That’s when you have time for the vehicle number and details. The basics of exposure and composition are in the guide to taking good photos of trains.
- Only enter publicly accessible areas. Tracks, operational railway land and sidings are off limits and dangerous – without exception.
Common mix-ups
It points to the Class 4110 if …
- two rows of windows are visible one above the other
- the train forms a fixed formation with no separate locomotive
- the bogies sit under the carriage gangways
- the class marking starts with 4110
Look more closely if …
- you see a double-deck train but can't see the front of it
- the livery doesn't match the known schemes
- the train is running on a route where you don't expect it
It's not a 4110 if …
- a standalone locomotive with its own class marking stands at the front
- the carriages have only one row of windows
- the class marking starts with 1 or 2 – then it's a locomotive
- a country code other than A appears next to the number
The last point is especially worth heeding in Austria. Vehicles from several countries and operators run on the main routes, and double-deck multiple units from the same platform are also common outside Austria. Only the complete vehicle number including the country code turns the observation into a reliable sighting.
Verdict
The Class 4110 is a good example of how vehicle designations and body types need to be read together: the leading 4 says “electric multiple unit”, the double row of windows says “double-deck”, the missing locomotive front says “fixed formation”. Together that gives you an identification within seconds – the vehicle number then reveals the specific unit.
In short
Two rows of windows, no locomotive front, bogies under the gangways, marking 4110: a double-deck Stadler KISS multiple unit in Austrian long-distance service. Operator assignments are changeable – the number isn't.
Document multiple units properly
Number, location, date and service in one place – and you'll see which units you're still missing.
Summary
- The Class 4110 stands for double-deck Stadler KISS multiple units, whose classic field of use is the Westbahn line.
- Double-deck construction is an answer to limited platform lengths and high demand.
- The double-deck body, fixed multiple-unit formation and class marking are enough to identify it.
- Operator assignments in Austria have shifted several times and should always be checked against the current status.
Frequently asked questions
What is the Class 4110?
The Class 4110 denotes a double-deck electric multiple unit of the Stadler KISS type in Austrian long-distance service. It runs as a fixed formation with no separate locomotive, offers two passenger levels per carriage, and is designed for the Austrian traction power system of 15 kV at 16.7 Hz.
What does the 4 at the start of the class number stand for?
In the Austrian system the first digit of a four-digit class number encodes the vehicle type. 1xxx is an electric locomotive, 2xxx a diesel locomotive, 4xxx an electric railcar or multiple unit, and 5xxx a diesel railcar. The 4110 is therefore already identifiable as an electric multiple unit from the number alone.
What does the abbreviation KISS mean?
KISS is Stadler's product name for the double-deck multiple-unit family and stands for the German phrase "Komfortabler Innovativer Spurtstarker S-Bahn-Zug" (comfortable, innovative, quick-accelerating S-Bahn train). The platform is used in several countries, both in local services and – as in Austria – in fast long-distance variants.
How do I tell a multiple unit apart from a loco-hauled train?
By the front of the train. A multiple unit has a continuously styled front end that's part of the formation, with no interchangeable locomotive ahead of it. With a loco-hauled train you see a standalone locomotive with its own class marking, followed by carriages that can be uncoupled.
Why are double-deck trains built at all?
Because platform lengths and routes are limited. A double-deck train offers noticeably more seats than a single-deck one at the same train length. The price for that is longer passenger exchange times, because passengers spread across two levels and board and alight via stairs.
How do I recognise an articulated train with shared bogies?
By the gangways between carriages. Instead of two bogies under adjoining carriage ends, there's a single shared bogie there. If you count the axles along the train, you'll notice it quickly: the bogies sit exactly under the gangways, not in pairs in front of and behind them.
Who operates the vehicles?
Double-deck multiple units of the Stadler KISS type are established in Austria on the Westbahn line, among others in the service offered by WESTbahn. Assignments between vehicles and companies have shifted several times – treat this as changeable and check the current status through ongoing sightings.
How do I identify a specific train?
Via the vehicle number on the carriage body and the class marking. In the twelve-digit UIC number, the country code 81 stands for Austria; for multiple units the type code at the start differs from that of locomotives. The train number also helps to match it to the specific service.
Log your sighting of the ÖBB / Westbahn Class 4110 (Stadler KISS)
Date, location and vehicle number logged in seconds – and visible to the community.
Related classes
ÖBB Railjet (RJ / RJX)
The Railjet isn't a multiple unit but a fixed coach set with a locomotive at one end and a control car at the other. Here's how to spot it and tell RJ from RJX.
EMUÖBB Class 4744 / 4746 (Cityjet / Desiro ML)
Cityjet is the product name, 4744 and 4746 are the classes: here's how to recognise the ÖBB's Desiro ML EMUs and tell them apart from older commuter classes.
EMUÖBB Class 4024 (Talent)
The Class 4024 is the ÖBB's low-floor Talent EMU. Here's how to recognise it by its bogies and boarding – and how to tell it apart from the Cityjet and the 4020.
High-speedÖBB ICE (Classes 401/402/403 in service)
ICE sets run in cross-border long-distance services in Austria. Here's how to tell ICE 1, ICE 2 and ICE 3 apart and read off which country the vehicle is from.
Who is behind it
Groups, brands, manufacturers and operators – who owns whom and how to recognise them out in the field.
Where to see the ÖBB / Westbahn Class 4110 (Stadler KISS)
Specific viewpoints with lighting times, coordinates and an honest verdict on whether the trip is worth it.
Related guides from the blog
