Key takeaways
- Two names, one vehicle: Re 4/4 II is the classic Swiss notation, Re 420 the modern class designation.
- The designation reads directly: R for increased curving speed, e for electric, 4/4 for four powered of four axles, II for the second production series.
- A universal locomotive, not a specialist: the class hauls passenger and freight trains alike.
- Fastest way to identify it: count the axles, check the body shape, read the number.
- Duties and operators change – diagrams shift with every timetable change.
Contents
Fact file
| Vehicle type | Universal electric locomotive for passenger and freight trains |
|---|---|
| Railway administration | Swiss Federal Railways (SBB) |
| Years built | from 1964 |
| Wheel arrangement | Bo'Bo' – four axles, all powered (Swiss notation 4/4) |
| Maximum speed | 140 km/h |
| Electrification system | 15 kV / 16.7 Hz AC |
| Classic number range | from 11101 upwards |
| Modern class | Re 420 – the first digit stands for four powered axles |
Identifying features
Is this really the class in front of you?
- Four axles in two bogies, all powered – not a six-axle design
- Compact, boxy body with a continuous window band and narrow cab windows
- Single-arm pantograph on the roof, flat roof fittings
- Vehicle number classically starts with 11 or, in modern form, with 420
- Very broad range of duties: on passenger trains just as much as on freight trains
- Often seen in advertising or special livery rather than standard red
Updated: August 2026 – If a Swiss electric locomotive looks boxy, has four axles and you simply seem to find it everywhere, then there is a good chance you are looking at a Re 4/4 II – officially the Re 420 today. It is the SBB’s universal locomotive and at the same time the best example of how two designation systems live side by side in Switzerland. This page shows you both: how to recognise the locomotive and how to read its names.
Spotted a Re 420? Note the number.
With such a widespread class, it is the vehicle number that turns a sighting into information in the first place.
What is the SBB Re 420?
The Re 420, classically the Re 4/4 II, is a four-axle electric locomotive of the Swiss Federal Railways, procured from 1964 onwards. All four axles are powered, the wheel arrangement is Bo’Bo’, the maximum speed is 140 km/h, and it runs under the Swiss standard system of 15 kV at 16.7 Hz, which SBB Infrastructure maintains across the whole network.
Its real distinguishing feature is not a single technical value but its versatility. The class is neither a pure express locomotive nor a pure freight machine, but both. That is exactly why it shaped the look of practically every larger Swiss station for decades – and exactly why the train behind it is a poorer identification feature than with specialised locomotives.
The three features that are enough to identify it
You don’t need detailed knowledge to place a Re 420. Three observations suffice, and they work even from some distance.
Count the axles
Four axles in two bogies. Six-axle machines such as the Re 620 are immediately ruled out, as is anything with additional carrying axles.
Check the body shape
Boxy, compact, with narrow cab windows and a flat roof. That is the design language of the 1960s and clearly distinguishes it from the rounded Re 460.
Read the number
Classically it starts with 11, in modern form with 420. Find either form and the identification is unambiguous – regardless of which livery the locomotive carries.
If any doubt remains, comparing it with its sister classes helps: the Re 4/4 I is noticeably more compact and is no longer a regular-service vehicle today, while the Re 430 is the third series, designed for heavy train operation. How to actually find and correctly read vehicle numbers in service is explained in the guide to the UIC number and its system.
Fraction or class number? Both are correct
In Switzerland two designation worlds meet. The classic notation describes the vehicle, the modern class is made for databases and international systems. Anyone who wants to talk shop in the scene should be able to read both.
| Classic | Modern | Axles | Character |
|---|---|---|---|
| Re 4/4 I | Re 410 | four, all powered | light express locomotive, historic |
| Re 4/4 II | Re 420 | four, all powered | universal locomotive for passenger and freight trains |
| Re 4/4 III | Re 430 | four, all powered | sister series designed for tractive effort |
| Re 460 | Re 460 | four, all powered | modern long-distance locomotive, Lok 2000 |
| Re 6/6 | Re 620 | six, all powered | heavy freight locomotive |
How to read the designation piece by piece
R stands for increased curving speed, the lower-case e for electric traction, the fraction 4/4 for four powered of four axles, and the roman numeral II for the second production series. Four characters, four statements – no reference book needed.
See what's just been reported
Community sightings show you which vehicles are currently out on your line – before you set off.
Where you find the Re 420
Because the class is universally deployable, there is no single line where you are guaranteed to find it. There are, however, types of places where your odds are higher than elsewhere. A large interchange and border station such as Basel SBB is one of them. So is the freight hub of Bellinzona, where shunting and line duties run closely side by side. The trans-alpine combined transport of operators such as Hupac is a defining presence there.
| Location | Chance of a sighting | Why |
|---|---|---|
| Large hub stations | high | Many train categories, locomotive changes and longer dwell times |
| Freight corridors | medium to high | The class also runs on freight trains |
| Regional services with loco-hauled coaches | medium | Where loco-hauled trains run, it is an obvious choice |
| Pure multiple-unit lines | low | No vehicle with a separate locomotive runs there |
| Station approach roads and stabling areas | medium | Locomotives wait between two duties – often visible from outside |
Duties change over time
Which diagrams the Re 420 currently runs on shifts with timetable changes, vehicle procurement and contract awards. Older lists you find online therefore often describe yesterday's situation. Check the current picture with real-time data and your own observation.
How to follow Swiss trains live and turn that into realistic tour planning is described in the guide to tracking trains live in Switzerland.
Photo tips for the Re 420
The locomotive is a rewarding subject: clean lines, compact proportions, clearly legible markings. Framing it well doesn’t require any special equipment. At a classic line-side photo spot such as the Gotthard north ramp near Wassen, the boxy shape comes across especially well.
Choose a three-quarter angle
An angle of about 30 to 45 degrees shows the front and the side of the body at the same time. The boxy body appears three-dimensional rather than flat as a result.
Include the whole side of the body
With advertising liveries, the real information sits on the side. Plan the framing so it is all in shot.
Prefer flat light
The edges stand out best in the morning and late afternoon. Midday light makes the smooth surface look dull.
Keep your distance
Mind the platform edge and stay clear of the track area. For closer shots, use focal length, not steps.
The underlying technique – shutter speed, panning, plane of focus – is covered in the guide to taking good photos of trains. Anyone specifically hunting for special liveries will find the approach in the article on finding advertising liveries and special paint schemes.
Common mix-ups
It points to a Re 420 if …
- the locomotive has four axles in two bogies
- the body looks boxy and compact
- the number starts with 11 or with 420
- it turns up in front of very different types of trains
Look more closely if …
- an advertising livery changes the familiar proportions
- you can only see the modern class number and want to place the series
- a sister series that looks similar is standing next to it
It is not a Re 420 if …
- you count six axles – then you are looking at a Re 620
- the front is rounded and aerodynamically shaped – that points to the Re 460
- the designation starts with Ee, Am or HGe
Its modern counterpart on long-distance services is the Re 460 (Lok 2000) – the same number of axles, but a completely different design language. Anyone who can tell the two apart with confidence has understood the leap between two vehicle generations.
Conclusion
The Re 420 is the locomotive with which you learn the Swiss system best. It is common enough that you encounter it regularly, while carrying both designation worlds in its name at once. Four axles, boxy body, number starting with 11 or 420 – nothing more is needed to identify it. It stays interesting through its liveries and through the fact that its duties shift with every timetable year.
Bottom line
Re 4/4 II and Re 420 are the same locomotive: four-axle, boxy, universally deployable. Identify it by axle count, body shape and number – log it by number, livery and date, because both of those change.
All your Re 420 sightings in one place
Number, livery, location and date in one app – so you can see straight away which machines you're still missing.
Summary
- The Re 4/4 II has been the backbone of Swiss locomotive traffic for decades and still shapes the look of many stations today.
- Its double designation makes it the best example of the transition from the fraction notation to the three-digit class system.
- Axle count, body shape and number are enough to identify it – no detailed knowledge is needed.
- Because liveries and duties change, it is worth logging every sighting with number and date.
Frequently asked questions
What is the difference between Re 4/4 II and Re 420?
It is the same locomotive. Re 4/4 II is the classic Swiss designation made up of letters and a fraction, Re 420 the modern, computer-readable class designation. Both notations are in everyday use: older sources and conversations among railway enthusiasts mostly use the fraction, official vehicle data the three-digit class.
How do I recognise a Re 4/4 II at a station?
By three things: it has four axles in two bogies, a compact boxy body, and a number that classically starts with 11 or, in modern form, with 420. Because the class runs on both passenger and freight trains, the train behind it is a less reliable identification aid than with specialised locomotives.
What does the roman numeral II mean?
It marks the second production series of the Re 4/4 family. Before it came the lighter Re 4/4 I, and after it the Re 4/4 III, designed for mountain lines. All three are four-axle electric locomotives, but differ considerably in design, size and focus of use.
How fast does the Re 420 go?
The maximum speed is 140 km/h. That is only reached where the line and the train allow it – in everyday operation the timetable sets the pace. Locomotives such as the Re 460 were later procured for faster long-distance services.
Does the Re 420 haul passenger or freight trains?
Both. That is exactly what makes it a universal locomotive: it is not specialised for high speed or for pure mountain haulage, but can be used across a broad range of duties. Anyone looking for it can therefore find it at almost any larger station in the country – though which diagrams it currently runs on changes constantly.
What does the 4 in Re 420 mean?
For Swiss electric locomotives, the first digit of the three-digit class can be read as the number of powered axles: Re 410, Re 420, Re 460 and Re 465 are four-axle, Re 620 is six-axle. The following two digits distinguish the designs within that group.
Why do you see so many Re 420 in special livery?
Because the class is numerous, highly visible and has been in service for many years – ideal conditions for advertising and anniversary liveries. For spotters that means the number alone only describes half a sighting. Livery and date belong with it, because both change.
How do I tell a Re 420 and a Re 460 apart?
By the shape. The Re 420 has a boxy, compact body from the 1960s, while the Re 460 has a rounded, aerodynamically shaped front from the 1990s. Both are four-axle, but look completely different. When in doubt, the vehicle number settles it here too.
Log your sighting of the SBB Re 420 (Re 4/4 II)
Date, location and vehicle number logged in seconds – and visible to the community.
Related classes
Re 4/4I
The Re 4/4 I was the first series of the Swiss Re 4/4 family: a light four-axle express engine. Today you mostly meet it at private railways and heritage societies.
Electric locoSBB Re 430
The Re 430 is the third series of the Swiss Re 4/4 family and is designed for tractive effort. This page shows you how to tell it apart from the similar Re 420.
Electric locoSBB Re 460 (Lok 2000)
The Re 460 is the SBB's modern long-distance locomotive: 119 machines, 200 km/h, an unmistakably rounded front. Here's how to recognise it and its sister designs.
Electric locoSBB Re 465 (BLS)
The Re 465 is the BLS variant of the Lok 2000 family and is easily mistaken for the Re 460. This page shows you how to tell the two apart with confidence.
Electric locoSBB Re 474 (Vectron CH)
The Re 474 is a four-axle multi-system freight locomotive for the Switzerland–Italy corridor. This page explains electrification systems, naming and recognition features.
Electric locoHGe 4/4
The HGe 4/4 is an electric rack locomotive for Swiss metre-gauge railways. This page decodes the designation and shows what to look for in the field.
Who is behind it
Groups, brands, manufacturers and operators – who owns whom and how to recognise them out in the field.
Hupac
Hupac organises combined transport through the Alps: its own wagons, its own terminals, its own timetable. The locomotive in front almost always belongs to somebody else. That's exactly why a Hupac train is identified by its wagons, never by the loco at the front.
GroupSBB Cargo International
SBB Cargo International was founded for a single purpose: through freight trains between northern Europe and Italy. The company is majority-owned by SBB, but not entirely – and despite its name, it doesn't run any traffic within Switzerland.
InfrastructureSBB Infrastruktur
SBB Infrastruktur isn't a separate company, but a division of SBB with separate accounts. It maintains most of the Swiss standard-gauge network – but not all of it: BLS, RhB, MGB and SOB have their own tracks, their own rules and their own rolling stock.
State railwaySchweizerische Bundesbahnen (SBB)
SBB doesn't label its vehicles with a class number but with a combination of letters that codes speed, coach class and type of traction. Anyone who can read Re, RABe and Ee identifies a Swiss vehicle faster than any database lookup.
Where to see the SBB Re 420 (Re 4/4 II)
Specific viewpoints with lighting times, coordinates and an honest verdict on whether the trip is worth it.
Basel SBB
No other station in Europe brings three national rail systems together as tightly as Basel. Swiss long-distance trains, its own French station section, and just a few tram minutes away a station on Swiss soil operated by DB – plus the most important north-south freight hub on the Alpine route.
Freight hubBellinzona
Bellinzona is the point where all the Gotthard traffic fans out again on the southern side: towards Locarno, towards the Ceneri and Lugano, and on into Italy. Add to that a workshop tradition, Mediterranean light and three castles above the tracks.
Freight hubErstfeld
For more than a century, Erstfeld was the place where heavy trains picked up banking locomotives before tackling the Gotthard north ramp. Since the base tunnel started running beneath the mountain, the place has changed – it has stayed interesting, but for different reasons.
Mountain lineGotthard North Ramp at Wassen
Between Gurtnellen and Göschenen, the Gotthard mountain line spirals up the hillside through loop tunnels, passing Wassen at three different heights along the way. Since the base tunnel opened, far fewer trains run here – but the views remain among the best in Switzerland.
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