Incorrect tagging for maxspeed:type in the UK

[NathanARF]

I've seen a few changesets where a user has answered the speed limits quest, and the tag maxspeed:type=GB:zone30 has been applied to the map. This tag is incorrect as 30 zones do not exist in the UK, only 20 zones and 40 zones. Users should be prevented from inputting any values other than 20 or 40 to answer speed limit quests in the UK with a speed limit zone.

[Helium314]

Actually maxspeed:type=GBzone30 seems really bad, it should at least be maxspeed:type=GB:zone30.

But otherwise it's on the user. If the user answers it's a zone with 19 kmh limit, then SC will tag zone19.

[NathanARF]

Sorry, missed a : in there.

Actually, if a user types in 19, a message will come up saying "Are you sure? This speed limit looks implausible", so there is a level of prevention that needs to be applied to the 30 value, just with a different message perhaps - users may not understand exactly how 30 mph speed limits should be tagged

[FloEdelmann]

Could you link to some of the changesets in question? Have you already asked the user about this?

[matkoniecz]

so there is a level of prevention that needs to be applied to the 30 value, just with a different message perhaps

note that 30 in such case would be wrong only in UK

is it problem with single user? or more wide?

[NathanARF]

Three users in the past few days
https://www.openstreetmap.org/changeset/150269316#map=18/50.69686/-2.10863
https://www.openstreetmap.org/changeset/149670842#map=14/50.4130/-4.2552
https://www.openstreetmap.org/changeset/150346330#map=19/51.64014/-2.35272
https://www.openstreetmap.org/changeset/149992725#map=18/51.74024/-2.22937

[westnordost]

This is not a bug. It is what the user(s) selected. The following video shows what the user has to select and input in order for this to be tagged:

Maxspeed.mp4

I.e. the users answered that it is within a slow zone and a picture of the sign was shown for them to input what they see on that sign.

[NathanARF]

Yes, I understand the process works as intended, but that should not be the case as a 30 zone does not exist in the UK. Only the tags maxspeed:type=GB:nsl_restricted and maxspeed:type=sign should be used with maxspeed=30 mph.

[westnordost]

So, you would like us to add a sanity check alike the "this speed limit looks implausible, are you sure?" in regards to slow zones.

How do you think such a check should look like?

[NathanARF]

Something along the lines of "Are you sure this is a speed limit zone? Please check you can see a speed limit zone sign"?

[westnordost]

I meant, when should this warning appear? Under which circumstances / given which user input? El 24 de abril de 2024 11:22:47 CEST, Nathan Acheson ***@***.***> escribió:

…

Something along the lines of "Are you sure this is a speed limit zone? Please check you can see a speed limit zone sign"? -- Reply to this email directly or view it on GitHub: #5592 (comment) You are receiving this because you commented. Message ID: ***@***.***>

[NathanARF]

Well 30 is likely the most common mistake due to the way 30 mph speed limits work in the UK. A message for that input should be fine.

[westnordost]

Well, we need to think worldwide, because the quest is available worldwide. And surely, the same message should also be shown for an input of 31, 40 etc., no?

[NathanARF]

Well, those are likely mistakes, whereas the 30 zone tag has been applied by multiple people, showing a bigger issue. I think the "Are you sure?" message covered by strange numbers is fine for the other values, it's just the 30 that appears to be the issue.

[westnordost]

But an input of 30 should not lead to a warning message everywhere in the world, right??

[NathanARF]

Well, this is only an issue in the UK

[westnordost]

Sigh... it seems I fail in bringing across what I want from you.

I am not going to add special rules in the code for every single country code, like if (country == UK && input == 30) showWarning() because this approach would just be an endless source of similar requests: What about an input of 29 or 31? What about Jersey (not part of the UK)? What about input of 50 (etc?) in non-mph-countries? What about the US, Liberia? What about..., what about? That's busywork. I want a solution that covers all.

Anyway, I can think of something myself, but then I would like to know from you why especially the input of 30 is that common of a mistake in the UK? You started changeset discussions on some of these changesets, so hopefully the users will be able to answer this.
Without understanding why this mistake occurs, any proposed solution may just fail.

[RubenKelevra]

@westnordost alright, what about adding a positive list for existing zones per country and warn if the user inputs something else?

There's the default speed limit article which is supposed to be machine readable in the OSM wiki.

I think it could be extended to list the zones in each country (or this could be added in some other article) and imported into SC while creating a new version.

This way there's no need to maintain this data in SC.

[matkoniecz]

Maybe it can go into country data? And if there is list defined complain about ones outside the list.

[westnordost]

That sounds like a huge effort for a small "Are you sure?" dialog. (Not only initial, but also continuous - maintenance.)

Also, what hinders road authorities to come up with new limits for speed signs on the spot? 30kmh zone is well known, but I don't see a reason why there shouldn't be a 20kmh zone, a 10 kmh zone, a 15kmh zone, etc.

[RubenKelevra]

Maybe it can go into country data? And if there is list defined complain about ones outside the list.

Yeah sure, but that would need continuous maintenance, compared to a wiki approach where people would maintain it for you.

[RubenKelevra]

That sounds like a huge effort for a small "Are you sure?" dialog. (Not only initial, but also continuous - maintenance.)

Also, what hinders road authorities to come up with new limits for speed signs on the spot? 30kmh zone is well known, but I don't see a reason why there shouldn't be a 20kmh zone, a 10 kmh zone, a 15kmh zone, etc.

Germany already got 20 km/h zones... and there were 10 km/h 😇

[mnalis]

There's the default speed limit article which is supposed to be machine readable in the OSM wiki.

Perhaps I am misunderstanding, but how would that specific wiki page help @RubenKelevra ?

That page says it is about "Legal default speed limits apply if no explicit speed limits are set by appropriate signs". I.e. what is default speed limit for urban, rural, motorway etc. road if no sign is present.

If some kind of speed limit sign is present (i.e. maxspeed:type=sign, maxspeed:type=CC:zoneXX etc), I would guess that it is usually because the current street has speed limit which is different then those present in default speed limit wiki?

For example, when I count different maxspeeds used in Croatia, majority of them are not present in that wiki.

And when I count different maxspeed:type (to get zones, which this issue seems to be about) literally none of the Croatian zones (zone10,zone20,zone30,zone40) are present in default speed limit wiki. So, at least here, it would always give a confirmation warning for any zone (which would suck)? (that is, if I understood the idea correctly in the first place, which is not given 😃)

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Better automated solution might IMHO be that on-new-release we build a list of allowable maxspeed:type (e.g. by looking up all values which have 50+ (or whatever) uses, e.g. this taginfo for United Kingdom), and warn on anything not in the list, but:

• I have not checked if all countries have per-country taginfo database
• there is still the possibility that there be 50+ incorrect values on OSM at the moment of the release
• as noted by BDFL, I'm also not sure if the effort would be worth it.
  I think SC does something similar for ATM operators, but that one saves a lot of typing and mistakes (but has same problem as point above -- if OSM has several variations of operator name, all of them will be present in the search. Which is currently the case in Croatia, for example. Mechanical edit would be relatively easy to fix them, but the sheer bureaucracy around doing that makes me postpone those fixes every time 😢)

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Also, perhaps it might be useful to actually contact those users who mapped wrong non-existent values (esp. if they same user did that same error several times or more) and check with them why it might be happening? Sure, fat fingers are one explanation, but there might be others...

[NathanARF]

Better automated solution might IMHO be that on-new-release we build a list of allowable maxspeed:type (e.g. by looking up all values which have 50+ (or whatever) uses, e.g. this taginfo for United Kingdom), and warn on anything not in the list

All those listed there, except maxspeed:type=construction are the only tags that should be used in the UK (with the maxspeed:type=GB-WLS:nsl_restricted only being somewhat adopted after a discussion on TalkGB). I recently spent time removing/fixing incorrect tags, hence why I brought this up in the first place.

Also, perhaps it might be useful to actually contact those users who mapped wrong non-existent values (esp. if they same user did that same error several times or more) and check with them why it might be happening? Sure, fat fingers are one explanation, but there might be others...

I did contact those who made the mistakes but the only reply thus far is a comment linking to this exact thread.

[westnordost]

I did contact those who made the mistakes but the only reply thus far is a comment linking to this exact thread.

Ok, let's wait a bit. Did you actually ask them or have a hunch why they answered this way?

[NathanARF]

I suspect because it's somewhat common to say "30 zone" to refer to general widespread 30 mph speed limits in the UK, and so these users selected the zone sign when answering the quest as a result. I didn't actually ask each user why they made this mistake, just a general comment on how to correctly tag such limits. I will add a question onto the end of each changeset

[westnordost]

Are these "30 zones" signed in some way or are they set implicitly by the presence of street lighting?

[NathanARF]

Many of the incorrect tags were applied to 30 mph speed limits where there are no repeater signs due to the presence of street lights (where the correct tag is maxspeed:type=GB:nsl_restricted) although one example was an unlit road (where the correct tag is maxspeed:type=sign)

[westnordost]

So, would changing the wording to "It's within a signed (slow) zone" make it clear?

[NathanARF]

Potentially

[westnordost]

I implemented showing a warning on entering a not-really-slower-than-normal speed limit in the slow-zone sign input, also shown for odd values such as "17" etc.

[riQQ]

The wording change was reverted in b89db4a.

[westnordost]

because looking at the translations, some are already a bit awkward, with that "(slow)" in there. Adding another adjective will result in even more awkward wording for some translations that may end up being confusing.
More importantly, adding the word may evoke the wrong notion that for a slow zone to be tagged as such, there needs to be a sign on that street, which is usually not the case with slow zones - there are only signs at the entrance and at the exit to such zones.