Key takeaways
- BLS AG is one of Switzerland's big railway companies, with a focus on passenger services.
- Summit tunnel and base tunnel are two completely different answers to the same question: how to cross a mountain range.
- The mountain line is visible, the base tunnel isn't – that decides where spotting is possible at all.
- CH-BLS in the data panel is the reliable feature, not the livery.
- A name stem is no proof of a group: the same initial letters don't automatically mean the same company.
Contents
Fact file
| Business area | Passenger services, focusing on regional and RegioExpress services |
|---|---|
| Legal form | Aktiengesellschaft (AG) – public limited company |
| Country | Switzerland |
| Vehicle keeper marking (VKM) | CH-BLS |
| Form of name | Letter abbreviation as the company name, with no place names in today's branding |
| Vehicle designation | Swiss system of letters and axle fraction, plus modern number series |
How to recognise this operator
Is this really BLS AG?
- Data panel with the country code CH- and the vehicle keeper marking BLS
- Regional multiple units on regular-interval services, some of them double-deck
- Vehicle designations following the Swiss system, supplemented by modern number series such as RABe
- Deployed on lines with pronounced differences in altitude – long ramps, engineering structures, tunnels
- The name stem BLS also appears at a separate freight company
- Liveries change over the years – the marking remains the reliable feature
Updated: August 2026 – Two trains run the same route, and yet you only see one of them: one climbs into the light over a mountain line, the other disappears into a base tunnel. It’s exactly this difference that shapes railway operations in the Alps – and with it, where spotting is possible at all. This page introduces BLS AG and uses its setting to explain how a mountain line with a summit tunnel differs from a deep-lying base line.
Spotted a train in the Alps? Record it.
Vehicle, place and time in one sighting – captured in seconds with Traintrack.
What is BLS AG?
BLS AG is one of the big railway companies in Switzerland, with a focus on passenger services. The only bigger one in the country is the state railway, Schweizerische Bundesbahnen (SBB). Today the company name consists of the letter abbreviation itself – a form that’s common in Switzerland and whose origin is no longer visible in the name. How Swiss railway names arise from chains of place names, by contrast, is shown by the Chemin de fer Lausanne–Echallens–Bercher.
Important for identification: a shared name stem is no proof of a corporate link. This database has a separate freight entry for BLS Cargo AG. Whether and how two companies with similar names are connected is only stated in the commercial register – not by the branding on the vehicle.
Mountain line and summit tunnel: two answers to the same mountain
A mountain range can be crossed in two fundamentally different ways, and both still shape operations today.
The classic solution is the mountain line with a summit tunnel. The railway gains height over long ramps, often with spiral tunnels, viaducts and tight curves, and then crosses the ridge in a comparatively short tunnel near the highest point – the summit. The second solution is the base tunnel: deep inside the mountain, very long, with minimal gradient. Trains run fast and without losing height, but see nothing of the landscape – and aren’t seen either.
| Feature | Mountain line with summit tunnel | Base tunnel |
|---|---|---|
| Gradient profile | long ramps, significant gradients | almost flat |
| Structures | viaducts, spiral tunnels, retaining walls | one very long tunnel |
| Journey time | longer, slower | short, high speed |
| Visibility for spotters | high, many photo spots | practically zero between the portals |
| Weather dependence | high – snow, rockfall, wind | low in the tunnel itself |
| Demands on vehicles | tractive effort and braking capacity on the mountain | continuous power output and safety technology |
In practice that means: if you want pictures, look for the old alignment. If you want to count traffic, you need to know that a large part of it runs invisibly under the mountain. And if you collect vehicles, you’ll find longer observation windows on the ramps, because trains run more slowly there. Most of the Swiss standard-gauge network is maintained by SBB Infrastruktur.
What counts technically on the mountain
Gradients limit how much a train can haul and place demands on the brakes. Vehicles with a high proportion of powered axles are therefore common in the mountains – which you can read from the Swiss axle fraction in the vehicle designation, such as "4/4" for vehicles with all axles powered.
Identification in the field: step by step
Read the data panel
On the side of the vehicle, in the lower third. The country code CH- stands for registration in Switzerland, followed by the vehicle keeper marking – here BLS.
Note the vehicle designation
Swiss designations made up of letters and an axle fraction say more than any description of colours. Modern multiple units also carry number series.
Classify the train formation
A multiple unit on a regular-interval service, a locomotive-hauled train or a freight train? That decides what kind of working you're looking at.
Separate keeper and operator
The marking in the data panel names the keeper. The company running the train can be a different one – especially with partnerships and hired vehicles.
The general path from vehicle to company is described in the guide Who’s actually running it? Identifying the railway operator.
Which vehicles are running there right now?
Community sightings show you what's currently out and about – before you head into the mountains.
Context within rail operations
A big passenger company in Switzerland typically serves several levels: dense regional services around larger cities, longer RegioExpress services and routes through mountain areas. For observers, that means a wide range of vehicles – from low-floor local multiple units to double-deck units.
The database has entries for this such as the RABe 515 (MUTZ) as a double-deck multiple unit, the RABe 535 (Lötschberger) as a RegioExpress multiple unit and the main-line locomotive Re 465. Which vehicles run on which working at any given time changes – check the current situation before you plan a trip. Before a new vehicle is even allowed to run, testing and engineering service providers such as AEbt Angewandte Eisenbahntechnik are involved in test runs and certification.
Other big Swiss operators are set up in a comparable way, such as the SOB Südostbahn or the Swiss Federal Railways. For shots in narrow valleys with harsh backlight, it’s worth reading the guide How to take good photos of trains beforehand.
Assessing photo spots on mountain lines realistically
Mountain lines are considered rewarding subjects, but they’re more demanding than pictures suggest. Three factors decide whether a day is a success.
The first is the light. In narrow valleys the sun is only favourable for a few hours; slopes cast long shadows early on, and backlight is the rule, not the exception. The second is the weather: in the mountains the situation can turn around completely within an hour, and fog in the valley doesn’t automatically mean fog higher up – or vice versa. The third is accessibility: many attractive perspectives lie away from paths, and that’s exactly where legal and safe observation ends.
That leads to a simple planning rule: look for locations that can be reached from public paths, plan a fallback spot and expect longer waits. On ramp sections trains run more slowly, which noticeably lengthens the observation window – an advantage that flat high-capacity lines don’t offer.
Documenting sightings
Is your Alpine sighting complete?
- Vehicle designation and, if legible, the full vehicle number
- Country code and vehicle keeper marking from the data panel
- Point on the line as precisely as possible – portal, viaduct, station
- Date, time and direction of travel
- Train formation: multiple unit, locomotive-hauled train, number of units
- Weather and light, if you took photos
How to build this into a reliable collection over months is described in the guide to the sighting logbook.
Alpine hazards are real
Tunnel portals, track areas, retaining walls, service paths and railway land are off-limits. Away from marked paths there's a risk of rockfall, falls and, in winter, avalanches; the weather can change within a short time. Stick to established paths, find out about conditions and turn back if in doubt.
Common mix-ups
- Name stem taken as proof of a group – the same initial letters don’t prove a corporate link.
- Base tunnel and summit tunnel treated as the same – they lie at completely different altitudes and serve different purposes.
- Livery used for identification – colour schemes change over the years; the data panel stays.
- Vehicle keeper marking equals operator – the marking names the keeper, not necessarily the company running the train.
- Mountain line equals heritage operation – in Switzerland, old alignments are often still part of regular operations.
Conclusion
BLS AG is a big Swiss passenger company – and its setting is an object lesson in how different Alpine crossings can feel. Mountain line or base tunnel decides not only journey time and tractive effort, but also whether you get to see anything at all.
In short
For identification, CH-BLS in the data panel is what counts. For planning a trip, what counts is whether the line goes over the mountain or under it – that decides every photo spot.
Your Swiss sightings, sorted
Vehicle, number, place and date in one app – and an overview of what you're still missing.
Summary
- A big Swiss railway company with a focus on passenger services and vehicles following the Swiss designation logic.
- Alpine crossings work either as a mountain line with a summit tunnel or as a deep-lying base tunnel – with very different consequences for operations.
- For sightings, the data panel, vehicle number, location and time are what count.
- Deployments and liveries change; check the current situation before every trip.
Frequently asked questions
What is BLS AG?
A big Swiss railway company with a focus on passenger services. As with many Swiss railways, the legal form is an Aktiengesellschaft (public limited company); public shareholdings are common. Today the company name consists of the letter abbreviation itself, without any place names spelt out.
What's the difference between a summit tunnel and a base tunnel?
A summit tunnel lies high up in the mountains and is reached via long ramps – the line first gains height laboriously. A base tunnel lies deep inside the mountain, is considerably longer and needs hardly any gradient. One is a scenic line, the other a high-capacity link.
Why are mountain lines more interesting for spotters?
Because you can actually see something there. On the mountain line, trains run more slowly, through spirals and over engineering structures, often in open country. In the base tunnel they disappear at the portal and reappear kilometres away. Photographically, the old alignment is therefore almost always more rewarding.
Does BLS in another company's name mean the same company?
Not necessarily. The database has an entry with the same name stem in freight. A shared name stem doesn't prove a corporate link – what the actual relationships are is in the commercial register and can change.
What does CH-BLS on the vehicle mean?
CH is the country code of the country of registration, BLS the vehicle keeper marking. Together they form the keeper designation in the data panel, which sits right next to the twelve-digit number block. It names the vehicle's keeper, not necessarily the company currently running the train.
How do I read Swiss vehicle designations?
They consist of letters and an axle fraction: the fraction gives the powered axles and total axles, the letters the class or category and technology. The system is explained in detail on the page about the Appenzeller Bahnen; modern vehicles additionally carry number series such as RABe.
Where can I safely watch trains on a mountain line?
From publicly accessible locations and marked paths. Tunnel portals, track areas, retaining walls and service paths are off-limits. In the mountains, alpine hazards come on top: rockfall, sudden changes in the weather and avalanches in winter. Plan your equipment, time and route back accordingly.
Do vehicle deployments change often?
Yes. Which vehicle family runs on which working depends on diagrams, procurements and engineering works and changes constantly. The only reliable information is therefore what you read on the vehicle yourself: designation, number and data panel – plus place and time.
Log a sighting of BLS AG
Vehicle, location and date logged in seconds – and visible to the community.
Vehicles in the rolling stock database
BLS RABe 515 (MUTZ)
The RABe 515 'MUTZ' is BLS's double-deck multiple unit from the Stadler KISS family. Here's how to read the Swiss designation and recognise it on the platform.
ClassBLS RABe 535 (Lötschberger)
The RABe 535 'Lötschberger' is BLS's single-deck FLIRT multiple unit for RegioExpress services. Here's how to recognise it confidently and read its designation.
ClassSBB 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.
More operators
BLS Cargo AG
BLS Cargo AG is a Swiss freight operator. Its example is a good way to explain what the country code in the data panel really means – and what it doesn't.
Local & regionalSOB Südostbahn AG
SOB Südostbahn AG operates rail services in eastern Switzerland. To understand its network, you need to know how cantonal borders structure Swiss regional traffic.
Long-distanceSchweizerische Bundesbahnen (SBB)
The Swiss Federal Railways are the state railway of Switzerland and present across the whole country. This page shows what that means for the network and how to recognise its vehicles.
Local & regionalTransports Publics Fribourgeois (TPF)
Transports Publics Fribourgeois (TPF) operates public transport in the canton of Fribourg. The language border runs right through this area – and that shapes markings, place names and sightings alike.
Local & regionalTransports publics genevois (TPG – Bahnanteile)
Transports publics genevois is the urban transport operator in Geneva. The label “rail portion” in this database sets apart the rail-based part of its services from the rest of the urban transport network.
Local & regionalTransports Publics Neuchâtelois (transN)
Transports Publics Neuchâtelois (transN) run public transport with ties to the canton of Neuchâtel. Anyone who wants to understand Swiss railways should start with one term: the concession.
Who is behind it
Groups, brands, manufacturers and operators – who owns whom and how to recognise them out in the field.
AEbt Angewandte Eisenbahntechnik
AEbt Angewandte Eisenbahntechnik belongs to the kind of railway company that manufactures not a single vehicle and yet turns up in almost every approval process. The business is engineering, measurement technology and expert assessment – the work that sits between a finished vehicle and its first passenger run.
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 BLS AG
Spotting locations where this operator can be seen regularly – with viewpoints, light conditions and coordinates.
Bern Hauptbahnhof
Bern is the hub the Swiss timetable is built around. Two major railway companies share the same platforms, a narrow-gauge railway with its own terminus lies beneath the station – and the platforms are among the narrowest in the country.
Mountain lineLötschberg South Ramp at Hohtenn
Above the Rhone valley, the Lötschberg mountain line of 1913 runs like a balcony along the rock face: stone viaducts, galleries, tunnel portals and behind them Valais's four-thousand-metre peaks. Since the base tunnel opened, less runs here – but the high trail remains one of the best railway walks in Europe.
Related guides from the blog
