Standards & licences
Which formats, protocols and open-data licences the documented projects actually run on — and which cities run each one.
263 of 1167 published entries name a standard, a protocol or a licence in their own record. That layer decides whether a city's data can be read by anyone but its vendor, whether its trains can be resignalled by anyone but their supplier, and whether its "open" data is open in any sense a reuser would recognise. It has never been queryable before this page: it lived as sentences inside entries.
✔ Every published entry is checked against the public sources it cites before publication.
The open-data licence ladder
Ordered from the most permissive to the least. The rungs are an editorial judgement and live in a reviewable file; who stands on each one is computed from the entries.
| Licence | What it permits | Entries | Cities |
|---|---|---|---|
| PDDL | The Open Data Commons Public Domain Dedication: the city gives up its rights entirely. The most permissive rung on this ladder, and the rarest. | 11 | 7 |
| CC0 | Creative Commons Zero — a public-domain dedication. No attribution required, no conditions attached. | 21 | 16 |
| CC BY | Attribution only. Commercial reuse permitted, derivatives permitted — the workable default, and the most common licence in the atlas. | 36 | 29 |
| ODbL | The Open Database Licence: reuse freely, but a derived database must be shared alike. OpenStreetMap's licence, and it travels with the data. | 10 | 8 |
| CC BY-SA | Attribution plus share-alike: derivatives must carry the same licence. Open, but it constrains what the reuser may combine it with. | 7 | 6 |
| Open Government Licence | A family of bespoke government deeds — UK, Canada, and city-level adaptations. Usually attribution-only in substance, but each is its own document, which is the cost of a bespoke licence. | 6 | 5 |
| CC BY-NC | Non-commercial only — which the Open Definition does not count as open at all. A catalogue published this way is closed to exactly the reuse that would give it reach. | 6 | 5 |
| CC BY-ND | No derivatives — on a dataset. The bottom of the ladder: it forbids the one thing data exists to allow. | 1 | 1 |
The rung nobody is standing on. 234 published entries carry the open-data tag. 62 of them name a licence anywhere in their record; 172 name none at all. That is not a gap in this atlas — it is what those cities publish. A dataset offered without a licence is one a careful reuser cannot legally build on, whatever the portal calls itself.
Data formats and protocols
How a system publishes or moves its data. These are the entries where interoperability was a design decision rather than an afterthought.
Signalling and automation
What the trains and cameras actually run. The grades of automation are here because a procurement label and an operating reality are two different things.
Named too rarely for a page of their own: Mobility Data Specification (2) · OGC SensorThings (1) · FIWARE / NGSI (2) · MQTT (1) · ETCS (2). They are listed rather than dropped — a standard one city uses is still a fact about that city.
How these lists are made
Membership is derived, not curated. On every build each term is matched against the entry's own prose — its summary, impact, lesson and the editorial notes on its sources — and every listed entry prints the sentence the term was found in, so a wrong match is visible rather than hidden behind a count. What an editor decides is the vocabulary itself, each term's description, the order of the licence ladder, and the named exclusions for a term that means something else in a particular entry. The one such case today: a Melbourne heat platform whose budget line reads “EMV-funded” — Emergency Management Victoria, not the payment standard.
This is the reference layer, so it pairs with the rest of it: the glossary defines these terms, the topic guides argue about them, and the track record says how the projects using them turned out.