A long-lived team of Agile teams
The Agile Release Train (ART) is a long-lived team of Agile teams that incrementally develops, delivers and often operates one or more solutions in a development value stream. ARTs are generally 50 to 125 people, cross-functional, with every capability needed to define, build, validate, release and run what they own.
Why it is like this
Fifty to a hundred and twenty-five is roughly the largest group that can still plan together in one room and hold a shared mission. Below it you do not need a train; above it, the alignment the train provides starts to break down.
Not to be confused with
A department, a programme, or a project team. The ART is organised around a value stream rather than a function or a budget line, and "often operates" is doing real work in that definition: the train can own the thing in production, not just ship it.
In practice
If a train hands its solution to a separate operations group at release, it is a delivery programme wearing the name — which is fine, but it is not what the definition describes.
Source: SAFe Glossary (Scaled Agile, Inc.) — Agile Release Train (ART). Read on .
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Predict Check yourself
An organisation forms a 240-person "ART" covering an entire business unit. What does SAFe's own definition suggest?
Show the answer
It is roughly double the stated range — 50 to 125 is the band in which one train can still plan and align together, so this is likely several trains.
Oversized trains are the most common structural failure in a SAFe adoption: PI Planning stops working first, and the rest follows.