SZ Class 310 (Stadler FLIRT)

Updated: August 2026 – A train that looks all of a piece from front to back, with a pantograph on the roof and no locomotive at the front: that is an electric multiple unit, and in the Slovenian system this type of vehicle carries numbers in the 3xx block – including the Class 310. This page shows how to place multiple units reliably, what the Slovenian numbering system reveals and why the electrification system determines where a train can run.

What is the Class 310?

The SŽ Class 310 is an electric multiple unit, i.e. a continuous vehicle unit with its own traction that runs without a separate locomotive. Its class number clearly places it among the electric traction units in the Slovenian system: everything that begins with a 3 runs under the wires.

In Slovenia, electric operation specifically means 3 kV DC. That is a different system from Germany and Austria, where trains run on 15 kV at 16.7 Hz. For the multiple unit this results in a hard limit: its area of operation ends where the electrification system changes.

Reading the Slovenian numbering system

Slovenia does without type letters. Instead of “El” or “Di” as in Norway, a digit comes first, and it already carries the most important information.

Number range	Vehicle type	Recognisable by
3xx	Electric traction units	Pantograph on the roof
6xx	Diesel locomotives and diesel multiple units	Exhaust and radiator section instead of a pantograph
7xx	Diesel railcars	Mostly shorter units for branch lines
Manufacturer number	Modern multi-system locomotives	European type numbers such as 193 or 541

So the 3 at the start reliably tells you: overhead line. What it does not tell you is whether you are looking at a locomotive or a multiple unit – for that you need a second look at the shape of the vehicle. A six-axle machine such as the Class 363 also carries a 3 at the front, but is a classic locomotive with a rake of coaches behind it.

What multiple units mean for operations

The switch from locomotive-hauled trains to multiple units has the same reasons all over Europe: faster turnarounds, no running round of the locomotive, more even acceleration and lower boarding for passengers. For spotters, this switch has two consequences.

First, the picture becomes more uniform. Where different locomotives used to stand in front of different sets of coaches, the same unit now runs several times a day. Second, the focus shifts to the vehicle number: anyone who only notes “saw a multiple unit” has documented nothing. That is exactly why a carefully kept record pays off, as described in the guide to the sighting logbook.

On the Slovenian network, the electric multiple units sit alongside two other groups: the diesel units for lines without overhead wires, such as the Class 610, and further electric multiple unit classes such as the Class 312. Together they cover regional services, while locomotive-hauled trains are increasingly the exception.

What the system difference means for observers from Germany

Anyone coming from Germany brings a fixed expectation: 15 kV at 16.7 Hz, alternating current, the same technology from Flensburg to Basel and on through Austria into Switzerland. Slovenia breaks with this assumption. Here the wires carry 3 kV DC, and that changes more than you can see from the outside.

It becomes visible above all in three places. First, in the overhead line itself: DC networks work with considerably higher currents, which is why the overhead line is often more heavily built than in Germany. Second, in the vehicles: anything that only masters one system stays in the country – that applies to multiple units just as much as to older locomotives. Third, in operations at the borders, where either multi-system vehicles are used or the journey simply ends for a vehicle.

For spotters this is not a drawback but the real reason for the trip. Nowhere can you compare systems better than where two networks meet. If you photograph a Slovenian multiple unit, an older DC locomotive and a modern multi-system machine in one day, you have practically documented Europe’s electrification landscape – and afterwards you understand better why certain vehicles were built the way they were.

Spotting and photography: getting multiple units into the picture

Multiple units are more demanding to photograph than they seem. They are long, uniform and rarely have a dominant eye-catcher. These four points help.

• Three-quarter view instead of a head-on shot. An angle of around 30 to 45 degrees shows front and side at the same time and gives the long unit depth.
• Look for a curve. On a bend, the train arranges itself in the frame and does not look like a line. With articulated trains in particular, that is the decisive difference.
• Secure the number separately. A second, tighter shot of just the markings makes the sighting documentarily sound.
• Mind the platform edge. Multiple units also run in fast where they stop. Keep your distance, stay behind the safety line and never step into the track area.

If you want to approach identification more systematically overall, work through the guide to identifying classes. And because with multiple units the vehicle number is the decisive feature, the article on the UIC number and its check digit belongs right next to it – it also explains where to find the country code.

Common mix-ups

Verdict

The Class 310 represents the part of the Slovenske železnice fleet that carries everyday traffic: electric multiple units on the 3 kV network, unobtrusive, efficient and tied to the country. The vehicle type can be identified in two steps – look at the roof, decide between locomotive and multiple unit. For the exact class, only the markings on the vehicle count after that, and that applies to Slovenian multiple units in particular.