Key takeaways
- The S-tog is its own system: its own power supply, its own network, its own vehicles – there are no connections to the main network in regular service.
- Fastest way to identify it: a wide, squat articulated train with many short segments – and the Copenhagen location.
- Two lengths: there's a long and a short version, which makes the segment count the most useful thing to count.
- Litra instead of class: Denmark designates the S-tog vehicles with letter codes of the S series.
- These trains don't run in Germany – they're technically tied to the Copenhagen network.
Contents
Fact file
| Vehicle type | Electric articulated multiple unit for S-train services |
|---|---|
| Network | S-tog Copenhagen – a self-contained, closed local transport network |
| Electrification system | own DC system, separate from the 25 kV main network |
| Layout | multi-part articulated train with short car segments and a walk-through interior |
| Versions | one long and one short variant with a different segment count |
| Designation | Danish Litra letters of the S series |
| UIC country code | 86 for Denmark |
Identifying features
Is this really the class in front of you?
- Strikingly wide body in relation to its height – the train looks squat
- Many short segments with articulation joints rather than fewer long cars
- Fully walk-through interior along the entire train length
- Pantograph for its own DC system, which doesn't match the main network
- Runs exclusively on the Copenhagen S-tog network – never out on the open line inland
- Danish markings and Litra letters of the S series
Updated: August 2026 – A strikingly wide, squat train made up of many short segments that runs in a single city only: that’s the fourth generation of the S-tog in Copenhagen. This page explains how to identify it, why these vehicles technically can’t leave their network at all, and what that means for observation and photography.
Document local transport abroad
S-Bahn systems in particular are locally confined – anyone who's been there has sightings nobody else has.
What is the S-tog 4th generation?
The S-tog 4th generation is the current vehicle family of the S-Bahn Copenhagen, operated by the state railway DSB. These are multi-part electric articulated units with a fully walk-through interior that run exclusively on the Copenhagen S-tog network.
The crucial point to understand: the S-tog is not a subsection of the Danish line network, but a self-contained system. It has its own DC power supply, while the Danish main line network runs on 25 kV AC. On top of that come its own operating rules and platform conditions. Separate again is the driverless Metro Copenhagen, which shares neither tracks nor electrification system with the rest of the city’s rail transport. Vehicles from one system can’t be used on the other – unlike, say, the electric DSB IR4, which runs on the main network.
How to identify an S-tog train
Check the proportions
The body is very wide in relation to its height. That makes the train look squat and flat – an impression you won't recognise from German local transport.
Count the segments
Instead of fewer long cars, you see many short segments with articulation joints in between. The segment count distinguishes the long from the short version.
Factor in the location
These trains run only on the Copenhagen S-tog network. So the location is a fully valid identifying feature in itself – outside this network, it can't be an S-tog.
How to fundamentally work through features in a sensible order instead of getting stuck on details is shown by the guide to identifying classes.
Location is a feature
With closed local transport systems, you can rule out a lot of candidates purely by location. That applies equally to S-Bahns, metros and trams – so always note the location too.
A network with no connection to the rest
The technical separation of the S-tog explains almost everything you can observe in service. The comparison makes it clear:
| Feature | S-tog Copenhagen | Danish main line network |
|---|---|---|
| Electrification system | own DC system | 25 kV / 50 Hz AC |
| Vehicles | S-tog families only | locomotives, multiple units, diesel vehicles |
| Spatial extent | Copenhagen capital region | nationwide, including cross-border traffic |
| Interval | dense local transport interval | long-distance and regional services by timetable |
| Vehicle exchange between the networks | not possible in regular service | straightforward between lines |
The wide body shape is no coincidence here, but a direct consequence of this self-containment. Anyone operating a network that exchanges no vehicles with the rest of the country can design the loading gauge purely to their own needs and doesn’t have to take account of lines these vehicles will never run on. A wider body means more standing space per metre of train length and wider doors – exactly what a local transport system with short dwell times needs. The short segments joined by articulation, in turn, allow a walk-through interior in which passengers can spread out even while the train is moving. What at first looks like an unusual silhouette is therefore a very purposeful piece of engineering.
This separation leads to an insight that’s practically valuable for observers: there are hardly any surprises on the S-tog network. You won’t find a locomotive in front of a passenger train there, and no diesel multiple unit like the DSB IC3. Anyone looking for variety is better served by the main network; anyone wanting to document a clean, dense system finds ideal conditions on the S-tog.
Local transport belongs in the logbook too
Systems that only exist in one place make especially interesting entries later on.
Context for German observers
Here only honesty helps: S-tog vehicles don’t run in Germany. They’re technically tied to the Copenhagen network and can’t leave it. Anyone wanting to see them has to travel to the Danish capital region.
What does pay off, though, is the conceptual comparison. Anyone coming from Hamburg, Berlin or Munich knows S-Bahn systems with their own power supply – but the separation is carried through more consistently in Copenhagen than in many German networks. Near the border in Schleswig-Holstein and via the Fehmarn Belt axis, quite a bit will change about traffic between the two countries in the coming years, but the S-tog isn’t affected by that.
Within Denmark too: routing, intervals and vehicle deployment are subject to change. Network extensions, rebuilds and timetable changes regularly shift what runs where. Check the current status on site or via live sightings and real-time data, not in older overviews. Just how different Denmark’s rolling stock looks outside the S-tog is shown by the contrast with the diesel railcars of the DSB Desiro class.
Safety in local transport
A dense interval means: the next train comes at short intervals – often quieter than expected. Stay behind the platform edge, keep your distance from the track edge, and don't enter operational railway land. What's behind the platform isn't a photo spot. The basic rules are summarised in the guide on keeping a safe distance from the track.
Photo tips for S-Bahn vehicles
Make use of the interval
With dense traffic, you don't need to force an opportunity. Take your time choosing your spot and the light – the next train is coming anyway.
Show the width
The unusually wide body is the defining characteristic. A slightly angled front view makes this proportion visible, whereas a plain side shot throws it away.
Include the joints in the frame
The many short segments are the second defining feature. A view along the train clearly shows the articulation.
Plan for artificial light
Local transport stations are often covered or underground. Expect mixed light and check your white balance before you ruin an entire series.
How to combine exposure, viewpoint and composition for moving trains is covered in detail by the guide to taking good photos of trains.
Common mix-ups
It points to an S-tog if …
- the train looks strikingly wide and squat
- it consists of many short segments joined by articulation
- you're on the Copenhagen S-tog network
- the interior is walk-through throughout
Look more closely if …
- you want to tell the long from the short version apart – then count the segments
- you only see part of the train and can't tell the articulation
- you're at a station where S-tog and main-network platforms meet
It's not an S-tog if …
- the train is hauled by a locomotive
- you see a rubber-bellows front – that's the main network's multiple-unit family
- the vehicle is running outside the Copenhagen region
Verdict
The S-tog 4th generation is a lesson in closed local transport systems: own power supply, own vehicles, a clear spatial boundary. For identification, the location alone is often enough, supplemented by proportion and segment count. Anyone who travels to Copenhagen gets a vehicle in front of the camera that exists nowhere else – reason enough to record the sighting properly with location and date.
In brief
A wide, articulated train on the Copenhagen S-tog network with its own DC system: that's the 4th generation. You won't see these vehicles in Germany – they can't leave their network.
Capture sightings from abroad
Location, date, vehicle number – with Traintrack, even the trip to Copenhagen stays documented for good.
Summary
- The fourth S-tog generation is the backbone of local transport in the Danish capital region.
- Its wide body, divided into many short segments, makes it visually unmistakable.
- Because the network uses its own electrification system, these vehicles stay strictly confined to one area.
- Routing, service frequency and vehicle deployment change with timetable years and network expansion.
Frequently asked questions
What is the S-tog 4th generation?
It is the current vehicle generation of the S-Bahn Copenhagen, Danish S-tog. The trains are multi-part electric articulated units with a fully walk-through interior and a strikingly wide body. They run exclusively on the Copenhagen S-tog network, which is technically separate from the rest of the Danish line network.
Why can't the S-tog run on normal lines?
Because the S-tog network uses its own DC power supply, while the Danish main line network runs on 25 kV AC. The vehicles are designed for this one system alone. On top of that come their own platform heights and signalling and operating rules – a closed system in the best sense.
How do I identify a 4th-generation S-tog train?
By the proportions. The body is very wide in relation to its height, which makes the train look squat. Instead of fewer long cars, it consists of many short segments joined by articulation, and the interior is walk-through along the entire length.
What do the Litra letters on the S-tog mean?
Denmark designates vehicles with letter codes instead of class numbers. Codes from the S series are assigned to S-tog vehicles, distinguishing between the long and short versions. The exact combination is on the vehicle itself – that's where you should read it, rather than relying on lists.
Are there short and long trains?
Yes. The generation comprises a longer and a shorter version with a different segment count. For spotters that's handy: the number of articulation joints, or segments, is the simplest distinguishing feature and can be counted from the platform.
Can I see these trains in Germany?
No, that's not to be assumed. The vehicles are technically and operationally tied to the Copenhagen S-tog network and can't leave it. Anyone wanting to see them has to travel to the Danish capital region.
What's the difference between S-tog and the German S-Bahn?
The basic principle is similar: dense intervals, dedicated infrastructure, local transport in a metropolitan region. The difference lies in the technical implementation – its own power supply, its own vehicle family, and a network that's noticeably more clearly separated from the long-distance network in Copenhagen than in many German cities.
Where's a good place to photograph S-tog trains?
On publicly accessible platforms and in station areas with a good vantage point. Because the interval is dense, you don't need to wait for a particular vehicle – you can take your time choosing your spot and the light. Track areas and operational railway land remain off-limits.
Log your sighting of the DSB S-tog (4th generation)
Date, location and vehicle number logged in seconds – and visible to the community.
Related classes
DSB IR4 (ER Litra)
The IR4 is the electric answer to the IC3: the same rubber-nose front, but a pantograph on the roof. Here's how to tell the two apart with confidence.
DMUDSB Desiro (SA Litra)
The Desiro Classic at DSB is an old acquaintance from Germany: the same two-part diesel railcar as Class 642, just with Danish markings.
DMUDSB IC3 (MF Litra)
No European train is as easy to identify as the IC3: the rubber-nose front forms a walk-through gangway when coupled – a feature found nowhere else.
Who is behind it
Groups, brands, manufacturers and operators – who owns whom and how to recognise them out in the field.
DSB Danske Statsbaner
Denmark doesn't identify its vehicles with class numbers but with letter classes – the Litra. Add to that two electrification systems in one small country and a state railway that gave up freight operations more than two decades ago and now runs passenger services only.
BrandMetro Kopenhagen
Metro Kopenhagen runs without a driver, around the clock. It's not a railway operation, doesn't belong to the state railway, and shares neither track nor electrification system with the city's other rail traffic. That's exactly why it so often ends up in the wrong category in sighting lists.
Where to see the DSB S-tog (4th generation)
Specific viewpoints with lighting times, coordinates and an honest verdict on whether the trip is worth it.
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