Bombardier Flexity Berlin (GT6-12 ZRL)

Updated: August 2026 – A yellow tram, rounded nose, not a single step anywhere in the interior: in Berlin, that’s almost always a Flexity. The unwieldy type code GT6-12 ZRL looks cryptic at first, but it reveals body type, generation and vehicle variant at a glance. This page shows you how to read it and how to tell the Flexity apart from Berlin’s older types.

What is the Flexity Berlin?

The Flexity Berlin is the current low-floor tram generation of the Berliner Verkehrsbetriebe. It was built by Bombardier Transportation at the Bautzen works. It belongs to the internationally used Flexity platform, but is tailored specifically to the Berlin network – from car width to door layout to cab fittings. Not everything comes from a single manufacturer, though: drives, converters and control systems in tram building regularly come from suppliers such as Kiepe Electric.

Unlike railway vehicles, trams have no nationwide, unified class scheme. Every operator maintains its own type codes. In Berlin they’re built to be self-explanatory: GT for articulated tramcar, a digit combination for size class and vehicle generation, ZR for double-ended vehicle and L for the long version. Anyone who knows this logic can read GT6-12 ZRL straight off as a long, double-ended vehicle of the newer generation.

At the European level, though, things stay simple: electrically driven railcars carry the UIC type code 94 as the first two digits of the twelve-digit vehicle number. In everyday tram operation this number hardly matters, because operators work with their own short car numbers. How the twelve-digit number is structured for railway vehicles is explained in the article on the UIC number on the vehicle.

Single- or double-ended? The quickest test

Tram, light rail, underground: sorting out the categories

For identification it helps to keep the vehicle categories clearly separate. They differ in infrastructure, power supply and approval law – and therefore in almost everything you can see on the vehicle.

Category	Route	Power supply	Typical identifying feature
Tram	Street space and dedicated track beds	Overhead line, DC	Low-floor entry directly from the street
Light rail	Mixed form, partly tunnelled	Overhead line, DC	High and low platforms in the same network
Underground	Fully dedicated route	Usually third rail	No pantographs on the roof
S-Bahn	Railway lines	Overhead line or third rail	Railway train control, long trains
Regional multiple unit	Railway lines	Overhead line	Twelve-digit UIC number on the side wall

Photo tips for Berlin trams

Trams are rewarding to photograph, because you can get close to them legally and safely in the urban space – provided you mind two things: traffic and the track zone.

• Never stand in the track area. Tram tracks are operational railway land. Even where they run in the street space, the shooting position belongs on the pavement or a traffic island.
• Look for curves. A multi-articulated car shows off its body type best in a curve, when the car sections twist against each other.
• Avoid backlight. The yellow livery washes out against the light. Side or raking light in the morning and late afternoon draws out the shapes better.
• Capture the number and destination display too. Together, both turn the photo into a documented sighting.

The details of composition – position, shutter speed, panning – are covered by the guide to good photos of trams. Where the worthwhile spots in Berlin are can be found in the tram-spotting guide for Berlin. And what’s legally allowed and where the limits lie is clarified in the article Are you allowed to photograph trams?

Why Berlin needs double-ended vehicles

The fact that part of the Flexity fleet was procured as double-ended vehicles isn’t a design choice, but an operational one. It also explains why the type is more interesting for spotters than the single-ended variant.

A classic single-ended car has a cab at only one end and doors on only one side. To reverse direction at the end of the line it needs a turning loop – a track loop that takes the whole train around. Turning loops cost space, and space is the scarcest resource of all in a grown urban area. Wherever a line is extended, wherever a terminus has to be relocated temporarily, or wherever engineering works force a reversal, a loop is often simply impossible to fit in.

A double-ended vehicle solves that: a cab at both ends, doors on both sides, direction reversal at a dead-end stub in a matter of seconds. The price is fewer seats, because the second row of doors takes up space, and a somewhat higher vehicle weight.

For observation, concrete consequences follow:

• Dead-end termini are reliable spots for double-ended vehicles. Where there’s no loop, nothing else can run.
• Engineering-works diversions shift double-ended cars onto lines they don’t normally run on – good opportunities for unusual combinations.
• Line extensions often mean new termini start out as a dead-end stub and only get a loop later.
• Operational reversing manoeuvres on the open line are only possible with double-ended vehicles.

It remains important: which type runs on which line is changeable. Vehicle deliveries, workshop status and engineering works constantly shift the pattern. If you’re looking for a specific variant, it’s therefore better to orient yourself by the infrastructure – by the terminus – rather than by a line list.

Common mix-ups

Three vehicle groups regularly lead to misidentification. The older GT6N and GT8N cars are also low-floor and yellow, but look noticeably boxier and flatter in the front section – that’s the feature that separates the two generations. The historic Tatra KT4D, by contrast, is unambiguous: a high-floor vehicle with entry steps and a much smaller body shape. And anyone coming from other cities can easily confuse the Flexity with other modern multi-articulated cars such as the NGT8DD from Dresden or the Leoliner from Leipzig – here, the city alone settles it: these vehicles are network-bound and don’t turn up anywhere else.

Verdict

The Flexity Berlin is a vehicle you learn once and then recognise across the whole network. A rounded front, continuous low floor, and on the ZR variant doors on both sides – that’s all it takes. The type code then supplies the finer distinction between short and long, single- and double-ended.