[Tagging] Documentation issues of PT tagging schemes (was: Re: Public Transport v3 — starting RFC)

Leo Gaspard osm-ml at leo.gaspard.io
Tue Jul 24 14:56:36 UTC 2018


Hi Ilya,

I unfortunately won't be anywhere near Milan anytime soon, but thanks
for the invitation :)

The problem I can see with your proposal is that it appears to be based
on PTv1, not on PTv2, which looks much more logical to me (even though I
still don't understand it completely). I mean, there are 8 tags in your
proposal for “Stops and Stations”, whereas if I try to adapt marginally
PTv2 I would get to public_transport=platform, bus=yes / tram=yes / ...
; which sounds more consistent and easy to use both for the mapper and
for the data consumer. Same issue with 5 tags for “platforms”.

Basically, I feel like (without anything to prove my point) just
reordering and rewording the documentation for PTv2 (by explicitly
marking some elements as “optional if the mapper feels like mapping
them” and not talking about things that were done once) and maybe minor
changes would be enough for a huge boost in usability of PTv2, without
needing to rollback to PTv1 :) (again, I don't know what I'm talking
about, but the feeling I had from PTv2 is that it tried to unify tagging
so that it's easier to both remember and programmatically use, and the
feeling I have from your current specification is that it's not really
unified)


On 07/24/2018 11:32 PM, Ilya Zverev wrote:
> Hi Leo,
> 
> As a person who tried for many years not to touch any public transport in OSM because of hard to understand tagging, I share your pain about missing tutorials and instructions. The situation with these is a bit better in the Russian part of wiki, because we don't have hordes of mappers eager to bikeshed every explanation.
> 
> The title of the proposal is a bit misfortunate. It is not a new schema that coexists with previous two. On the contrary, it (if accepted) will be the single reference schema that data processors and validators would be built against. The version is misleading, and I think I should've taken on SK53's suggestion to rename it to e.g. "Refined Public Transport Tagging".
> 
> What the proposal really is is a clarification of what PTv1/2 elements really mean and how and when to use them. I refrained from wording it as a tutorial, because the last time I did that, I've got a lot of rage over every tiny thing. Some people here are still angry at me for that. Proposals are not tutorials.
> 
> I hope this answers your points 1-5. If you read the new proposal carefully, you'll notice that unlike the previous proposals, it spends many words explaining reasons behind every decision. It also makes mapping routes simple, while keeping options for micromapping (see the "Examples" section).
> 
> PTv1 will never vanish, because we didn't have it in the first place. It was just a pile of tags (like highway=bus_stop) which everybody understood and which did not form a coherent "schema", and route relations that were basically collections of everything related to a route.
> 
> PTv2 (based on Oxomoa's schema) was an attempt at introducing an order into mapping. It failed with many mappers like you (and me), because it was based on industry standards, which are very sensible, but imply a state-of-art editing system behind them. Mapping a route in PTv2 is like writing a GTFS feed in the Notepad.
> 
> The new proposal is about shedding off all the complexity, and leaving only elements required for using stops and routes. Once (if) it is accepted, it would be very easy to write a tutorial, because then you would be able to learn it gradually. First with collecting bus_stop nodes in a relation, then with platforms, and so on. The new proposed schema is flexible, which means you don't have to learn all of it to map a proper route. I believe that will attract many new mappers to add their public transport routes.
> 
> Thank you for your opinion, and I would very much like to discuss how can we make mapping routes simpler. If you're in Milan these holidays, come to my talk on Sunday morning, and look for a public transport BoF meeting, most likely on Monday.
> 
> Ilya
> 
>> 24 июля 2018 г., в 16:55, Leo Gaspard <osm-ml at leo.gaspard.io> написал(а):
>>
>> My point of view, as a beginner in OSM who still hasn't understood how
>> PTv1 and PTv2 are supposed to work (and thus didn't read this specific
>> proposal, take this as generic comments on PT tagging in OSM):
>>
>> 1. Beginners are already at a loss, introducing a third (!) tagging
>> scheme will just make things worse
>>
>> 2. If I were developer of an OSM tool, I'd be facepalming as soon as I
>> saw the word “PTv3”
>>
>> 3. What is *really* needed is a clarification of what PTv[12] actually
>> mean. This is first and foremost a documentation issue, not a tagging
>> scheme issue.
>>
>> 4. If I understood correctly, it's possible to use PTv2 with as few
>> tags as PTv1, but noone really understands it because the documentation
>> is such a mess. So I think a proposal of “Clarification of the relative
>> importance of tags in Public Transportation tagging” would be great.
>>
>> 5. Such a proposal would “just” improve the documentation for PTv2 and
>> erase completely any reference to PTv1 from the wiki (or move it to a
>> “historic tagging scheme, no longer to be used, but that could be
>> necessary to understand for consumers until the migration has ended”
>> section)
>>
>> 6. I personally spent at least half an hour (didn't count) trying to
>> understand how to tag public transportation. After having tried to read
>> the wiki, I just ragequit. The *documentation* is the issue for public
>> transport, and adding a third tagging scheme will only make things worse.
>>
>> 7. Once the documentation about PTv1 will have vanished and about PTv2
>> will be clear (and once the names PTv* will have disappeared to just be
>> called “PT tagging”, in order to be less frightening for the beginner),
>> *then* it would be interesting to discuss incremental modifications of
>> the PT scheme. I guess that's where the changes you're proposing for
>> “PTv3” (something that I think should not ever happen, would it be just
>> for its name) would be interesting to integrate.
>>
>> 8. For my desiderata about the documentation, I think it should:
>>     1. Be simple to read
>>     2. Go from the simplest tagging elements to the most complex. For
>> example, if I understood correctly PTv2 (ie. likely not), something like:
>>         1. how to place public_transport=stop_position
>>         2. how to make a route relation
>>         3. how to make a master route relation
>>         4. how to add public_transport=platform for people who feel like it
>>     3. Fit in a single page (having to switch back and forth between
>> dozens of pages for PT is just impossible to do while keeping focus)
>>     4. Potentially, *at the end, once all important concepts will have
>> been explained*, link to pages of individual transportation methods
>>     5. Be written in a didactic style. Currently it's full of “There
>> was this for a long time, and also that and that, but that is made
>> possible by PTv2”. BUT WHAT SHOULD I DO? (sorry, that's not to be read
>> yelling, just my internal thoughts when reading this kind of
>> paragraphs). That's just not how we can make people do something, that's
>> just a way to mix up everyone's mind but the minds of people who
>> actively designed the scheme.
>>     6. Give instructions as for what to do when the information is
>> incomplete (eg. I saw a few stops but not the full route, but I've got a
>> picture of the list of stations, what should I do?)
>>
>> Again, these are my 2¢ as a beginner who tried to understand the current
>> way of tagging PT and just didn't understand it enough to try actually
>> mapping with it. Also, obviously, I can say how I would want the page to
>> be, but I can't do it myself because I just didn't manage to understand
>> in a reasonable amount of time the PT tagging scheme. So I'll have to
>> rely on you (yes, thou who readeth me) to write it, sorry!
>>
>>
>> On 07/20/2018 10:48 PM, Ilya Zverev wrote:
>>> Hi folks,
>>>
>>> As you might've noticed, in the past year there has been growing discomfort with the current Public Transport tagging schema. Of course, it brought order to our route relations, but also introduced a lot of redundant concepts. We've seen a couple proposals aiming to fix some of issues, but nothing stuck.
>>>
>>> Please consider this new revision for the PT schema, which addresses most of the issues, while keeping as backward compatible as possible:
>>>
>>> https://wiki.openstreetmap.org/wiki/Proposed_features/Public_Transport_v3
>>>
>>> I'd be happy to hear any suggestions. Next week, I'll be presenting it, among other things, during my talk "What's up with the public transport" at the State of the Map conference.
>>>
>>> Thanks,
>>> Ilya
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>>
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