Handle `source:maxspeed=DE:zone*` or `maxspeed:type=DE:zone*`

[tordans]

In Germany, I noticed that some data has a source-tag but no explicit maxspeed tag.

This is the case for the value DE:rural (or urban) which are supported by the app for both variants

• source:maxspeed https://westnordost.github.io/osm-legal-default-speeds/#tags=highway%3Dresidential%0Asource%3Amaxspeed%3DDE%3Arural&cc=DE
• maxspeed:type https://westnordost.github.io/osm-legal-default-speeds/#tags=highway%3Dresidential%0Amaxspeed%3Atype%3DDE%3Arural&cc=DE

However, there is also a "zone" schema, that is not yet supported. In the time I invested to look into this I did not figure out why there are so many different ways to describe the same information (as far as I can tell), but I found multiple combinations of key and value with "zone" in it.

Taginfo:

• source:maxspeed => search for 'zone' in the search filed https://taginfo.openstreetmap.org/keys/source%3Amaxspeed#values
• maxspeed:type => search for 'zone' in the search filed https://taginfo.openstreetmap.org/keys/maxspeed:type#values

Examples from the app:

• maxspeed:type=DE:zone20 does not work https://westnordost.github.io/osm-legal-default-speeds/#tags=highway%3Dresidential%0Amaxspeed%3Atype%3DDE%3Azone20&cc=DE
• source:maxspeed=DE:zone:20 does not work https://westnordost.github.io/osm-legal-default-speeds/#tags=highway%3Dresidential%0Asource%3Amaxspeed%3DDE%3Azone%3A20&cc=DE
• source:maxspeed=DE:zone30 does not work https://westnordost.github.io/osm-legal-default-speeds/#tags=highway%3Dresidential%0Asource%3Amaxspeed%3DDE%3Azone30&cc=DE

There are some more variants in https://github.com/FixMyBerlin/osm-scripts/blob/main/utils/Highways-MaxspeedData/utils/addMaxspeedProperty.ts or https://github.com/FixMyBerlin/osm-scripts/blob/main/utils/Highways-MaxspeedData/utils/addMaxspeedSourceProperty.ts#L61-L73.

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Suggestions on what to do with this…

• Add a list of unsupported special cases to the readme (with link on the demo page)
• Add support for those special cases

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PS: I hope, at some point someone will take the time to cleanup that tagging mess …

[westnordost]

DE:zone30 does not define an unsigned legal speed limit though, hence, interpreting this tag is out of scope of the "Default speed limits" wiki page and thus also this library:

It is signed, even explicitly with the proper maxspeed sign. According to taginfo, 99.64% of all roads tagged with DE:zone30 have a maxspeed=30 tagged, so if this explicit tag is missing, it really can be considered a tagging error..

[westnordost]

PS: I hope, at some point someone will take the time to cleanup that tagging mess …

Also, you forgot zone:maxspeed=DE:30 and zone:traffic=DE:zone30 🤣

[tordans]

Thanks for you input, westnordost! I agree with that. Also, your talk at SOTM 2022 helped to understand the tool more completely https://2022.stateofthemap.org/sessions/YWH3XD/