Key takeaways
- 425 and 426 are the regional variants of the same design that also produced the S-Bahn Classes 423 and 424.
- The quickest way to tell them apart within the family: the number of car sections – four for the 425, two for the 426.
- 425 and 435 belong together: 425 are the driving cars, 435 the intermediate cars of the same unit.
- Against their S-Bahn sisters, boarding helps: regional vehicles serve lower platforms.
- 160 km/h separates the regional variants from the family's S-Bahn classes, which are built for 140 km/h.
Contents
Fact file
| Vehicle type | Electric multiple unit for regional and local services |
|---|---|
| UIC type code | 94 – electric multiple unit or railcar |
| Train formation (425) | Two Class 425 driving cars, two Class 435 intermediate cars |
| Train formation (426) | Two-part short version made of two driving cars |
| Design | Articulated unit with Jakobs bogies, fully walk-through |
| Vehicle family | Construction family of Classes 423, 424, 425 and 426 |
| Electrification system | 15 kV / 16.7 Hz AC |
| Maximum speed | 160 km/h |
Identifying features
Is this really the class in front of you?
- Front shape of the 423 family: compact, softly rounded, large windscreen
- Four car sections on the 425, two on the 426 – train length is the quickest way to tell them apart
- Articulated unit with Jakobs bogies at the gangways, fully walk-through
- Boarding designed for lower regional platforms, usually with a step
- Regional-service seating instead of an S-Bahn interior with many standing spaces
- Vehicle number starts with 425, 426 or 435
Updated: August 2026 – It looks like an S-Bahn train but runs regional services: Class 425 is the regional variant of the 423 construction family, and 426 its two-part short version. This page explains how to recognise both, what the 435 has to do with it, and how to tell them apart from their S-Bahn sisters.
Spotted a family class? Note the number.
With four closely related classes, the number is the only permanently unambiguous detail – Traintrack logs it with place and date.
What are Classes 425, 426 and 435?
Class 425 is a four-part electric multiple unit for regional services, and Class 426 the two-part short version of the same concept. Class 435 denotes the intermediate cars of a 425 unit. All three numbers belong to the same construction family as the S-Bahn Classes 423/433 and 424/434.
Technically they are articulated units with Jakobs bogies and a fully walk-through interior, running under 15 kV / 16.7 Hz AC. The decisive difference from their S-Bahn sisters: the regional variants are built for 160 km/h instead of 140 and serve lower platforms, which shows up immediately at the doors.
Three numbers, one system
For newcomers, having three class numbers on one page at once is confusing. But they follow a simple order that applies right across German multiple units.
Driving cars carry the main number
For the four-part unit that's the 425. They have a cab and traction and give the unit its name.
Intermediate cars get their own group
The 435 isn't a different vehicle, but the intermediate car of the same unit – the same pattern as 433 with the 423.
Short versions get their own class
The two-part 426 is technically related but operationally a different vehicle – hence its own number.
The type code comes first
In the twelve-digit UIC number, everything starts with 94 for electric multiple units – regardless of family and number of sections.
The full system behind the twelve-digit number is explained in the guide to the UIC number; the order in which to work through features generally is covered in the guide to identifying classes.
Where it fits into rail operations
Regional multiple units of this design run the services between S-Bahn and long-distance traffic – on the Mittelrheinbahn just as in many other networks: longer stop spacing than in an S-Bahn network, but far denser than long-distance traffic. Where exactly that boundary runs is covered in the article on regional versus long-distance services.
| Location | Likelihood | Why |
|---|---|---|
| Electrified regional lines with regular services | highest | The class’s core deployment area |
| Terminus stations with turnaround time | high | Standing time allows relaxed side and number shots |
| Interchange stations with train splitting | high | Coupling and splitting are worthwhile shots in their own right |
| Pure S-Bahn trunk routes | low | Vehicles with high-level boarding fit better there |
| Lines without overhead line | very low | Electric multiple units need overhead wire |
Network details are snapshots
Which units run in which network depends on service contracts, depot allocation and vehicle swaps. After a tender, entire fleets can shift along with livery and markings. So always check the current picture via real-time data and community sightings.
Current deployments at a glance
See which units are being reported right now – and choose your spot accordingly.
Spotting and photo tips
The regional variants are more common than almost anything else on the electrified local network – and that’s exactly why it’s worth photographing them deliberately rather than in passing.
Show off the train length
The difference between the four-part 425 and the two-part 426 is the first feature. A shot showing the whole unit documents it.
Include the boarding area
The step and platform height reveal the vehicle's design. A frame with the door and platform edge says more than a front portrait.
Record whole coupled sets
Two-part units in particular often run coupled together. Note every number, or the formation won't be traceable afterwards.
Favour raking light
Mornings and late afternoon bring out edges and door seams. Harsh midday light leaves the smooth side wall looking flat.
Platform edge and track area
Even for a full side-on shot of a four-part train, the safety line doesn't get crossed. Track areas, operational railway land and stabling sidings are off limits – no exceptions.
Two-part or four-part: what train length says about operations
The fact that the same design exists in two lengths is no accident, but an operational answer to what bodies like the Karlsruher Verkehrsverbund (KVV) put out to tender. Demand on regional services swings widely – across the day, across the week and between individual line sections. A fixed train length would be too small at peak times and too large on a Sunday morning.
The solution is multiple traction. Because every unit has its own cab and its own traction, several can be coupled and split again without shunting. Two two-part units combined give a train length at peak times that’s halved again outside the peak. That’s exactly what makes the short 426 so useful: it’s the smallest sensible building block of this family.
A second application is splitting. Two units run together as far as a hub station, are split there and then serve different branch lines. For observers, such stations are especially rewarding, because coupling, splitting and the coupling point between two fronts can be watched closely – shots that a single through train doesn’t offer.
Practical tip: look for hub stations with train splitting
Where trains are split, they stand for longer than usual and in a formation worth photographing. Note every vehicle number involved – it's the only way to trace later which units travelled together and where they went afterwards.
Common mix-ups
The 425 is confused almost exclusively within its own family. For every case there’s exactly one reliable feature – and none of them is the livery.
| Confused with | Looks similar because | What sets it apart |
|---|---|---|
| Class 426 | identical front shape and design | the 426 is two-part, the 425 four-part |
| Class 423/433 | same construction family | the 423 is an S-Bahn vehicle with step-free boarding at a high platform |
| Class 424/434 | same family, also four-part | the 424 is an S-Bahn vehicle, the 425 a regional vehicle with different seating |
| Class 420/421 | similar operating segment in local traffic | the 420 is three-part and has no gangways |
It points to the 425 if …
- the train has four car sections and is fully walk-through
- the front shape matches the 423 family
- boarding is via a step at a lower platform
- the number starts with 425 or 435
Look more closely if …
- the train has only two car sections – then it's the 426, not the 425
- several units are coupled together and counting cars gets confusing
- you can't tell from the platform whether boarding is step-free
It isn't a 425 if …
- the train consists of three separate car bodies with no gangway
- boarding is step-free at a high S-Bahn platform
- a separate locomotive is pulling or pushing the train
Conclusion
Classes 425, 426 and 435 show how efficient modern vehicle procurement can be: one design, several versions, several class numbers. For spotters, that means the front shape alone decides nothing. Train length, boarding height and interior narrow it down, and the vehicle number decides. Working in that order lets you sort the whole family with confidence.
In short
The 423 family's front shape plus a step at boarding plus four car sections: that's the 425. Two car sections mean the 426, and step-free boarding at a high platform means the S-Bahn sisters.
Collect the whole family
423, 424, 425, 426 – with Traintrack you keep track of which units you're still missing.
Summary
- Class 425 is a four-part regional multiple unit from the 423 construction family, and the 426 its two-part short version.
- Both share front shape, articulated design and Jakobs bogies with their S-Bahn sisters.
- Boarding height, interior and top speed separate the regional from the S-Bahn variants.
- For a clear sighting, the full vehicle number is what counts in the end.
Frequently asked questions
What's the difference between Class 425 and 426?
Train length. The 425 is four-part, the 426 two-part. Both share front shape, design and technology. That makes the 426 look noticeably short, and it's used for services where a four-part unit would be too large – or it runs coupled with others when more capacity is needed.
What does Class 435 mean?
The 435 denotes the intermediate cars of a four-part 425 unit. Driving cars carry the 425, intermediate cars the 435 – the same double-class logic as 423/433 or 424/434. It isn't a separate vehicle but part of the same indivisible unit.
How do I tell the 425 apart from the S-Bahn Class 423?
By boarding, interior and environment. The 423 is built for high S-Bahn platforms and is step-free, while the 425 serves lower regional platforms and usually has a step. Then there's the seating: regional services favour seats, S-Bahn interiors fast passenger exchange.
How fast does Class 425 run?
Its maximum speed is 160 km/h. That separates the regional variants from their S-Bahn sisters in the family, which are built for 140 km/h. On main lines with mixed traffic, the higher figure is needed so the train doesn't become an obstacle.
Why does the 425 look like an S-Bahn train?
Because it comes from the same construction family. One basic design produced four classes for different purposes and platform heights: 423 and 424 for S-Bahn services, 425 and 426 for regional services. The family resemblance is deliberate and saves on development and maintenance costs.
What is a Jakobs bogie?
A bogie shared by two neighbouring car sections. So there's only one at the gangway instead of two. It's extremely useful for identification: if you count fewer bogies along the train than twice the number of car sections, you're looking at an articulated unit.
What does type code 94 tell you?
It sits at the first two positions of the twelve-digit UIC vehicle number and denotes electric multiple units and railcars. It doesn't distinguish by purpose – an S-Bahn train and a regional multiple unit carry the same 94, only the class number tells them apart.
Where does Class 425 run?
On electrified regional and local services. Specific networks and lines depend on service contracts and vehicle allocations and change with tenders and timetable years. Use current real-time data and community sightings if you're looking for something specific.
Log your sighting of the Class 425/426/435
Date, location and vehicle number logged in seconds – and visible to the community.
Related classes
Class 423/433
Class 423 is the face of Germany's modern S-Bahn and the founding member of a whole vehicle family. Here's how to recognise it and place its relatives.
EMUClass 424/434
Class 424 belongs to the 423 family but is designed for different platform heights. That's exactly what gives it away – and where most identifications go wrong.
EMUDB Class 420 / 421
The Class 420 is the original German S-Bahn train: three cars, no gangway between them, built from 1969. Here's how to recognise it – and tell it apart from the 423.
EMUClass 563 (Siemens Mireo)
Class 563 belongs to the Siemens Mireo family. How to recognise the Mireo, how the number blocks 463, 1463 and 563 relate, and what sets it apart from the FLIRT.
EMUBombardier Flexity Berlin (GT6-12 ZRL)
The Flexity Berlin is BVG's modern low-floor tram. The type code GT6-12 ZRL reveals almost everything – once you know how to read it.
EMUBombardier Leoliner (Leipzig)
The Leoliner is the low-floor tram developed in Leipzig, deliberately kept simple. How to recognise it and how it differs from the larger LVB types.
Who is behind it
Groups, brands, manufacturers and operators – who owns whom and how to recognise them out in the field.
Bodensee-Oberschwaben-Bahn (BOB)
The Bodensee-Oberschwaben-Bahn belongs to districts, towns and a municipality – not a group. Its blue trains run between Friedrichshafen and Aulendorf, and its abbreviation BOB is shared, of all things, with a Bavarian railway operating somewhere else entirely.
InfrastructureErms-Neckar-Bahn Eisenbahninfrastruktur AG (ENAG)
The ENAG owns the Ermstalbahn between Metzingen and Bad Urach – a short branch line at the foot of the Swabian Jura. It doesn't run any trains itself. This one line is a particularly clear example of just how many parties are actually involved in a railway.
InfrastructureKarlsruher Verkehrsverbund (KVV)
The Karlsruher Verkehrsverbund doesn't run a single train. It bundles fares, line numbers and livery – the actual driving is done by several companies. And this is exactly where the Karlsruhe Model was born, letting a tram switch onto the main railway line mid-journey.
BrandMittelrheinbahn
Mittelrheinbahn is the name of a service brand along the left-bank Rhine line, not the name of the company that runs it. Between Cologne, Koblenz and Mainz you'll encounter one of the densest mixes of regional, long-distance and freight traffic anywhere in Germany.
Where to see the Class 425/426/435
Specific viewpoints with lighting times, coordinates and an honest verdict on whether the trip is worth it.
Hamm (Westf) Hauptbahnhof
At Hamm, the Ruhr region's great routes go their separate ways: towards Hanover, towards Münster and towards Kassel. Add to that a freight share that hardly any other German main station of this size reaches – and a platform hall that ties the whole operation together.
Photo spotHohenzollern Bridge Cologne
The Hohenzollern Bridge is the busiest railway bridge in Europe – and one of the few top-tier spots that costs nothing and is open around the clock. A public footpath runs directly alongside the tracks on both sides, with the cathedral standing in the background.
Related guides from the blog
