[Tagging] maxspeed:type vs source:maxspeed // StreetComplete
osm at westnordost.de
Sat Sep 22 12:22:17 UTC 2018
Tagging an implicit speed limit explicitly for example in town with
maxspeed=50 is straightforward enough for Germany. It seems natural that
no specialist knowledge is required for that kind of thing. For a German.
But let's look at some other countries for the default urban speed limit.
Kerala in India (IN-KL):
maxspeed:conditional=40 @ (weight > 7.5)
maxspeed:bus:conditional=40 @ (weight > 7.5)
maxspeed:hgv:conditional=40 @ (weight > 7.5)
Punjab in India (IN-PB):
maxspeed:hgv:conditional=40 @ (weight > 6)
maxspeed:conditional=40 @ (weight > 6)
maxspeed:trailer:conditional=30 @ (weight > 6)
maxspeed:goods:conditional=40 @ (weight > 6)
maxspeed:goods:conditional=30 @ (weight > 3)
maxspeed:conditional=60 @ (23:00-05:00)
maxspeed:conditional=40 @ (weight > 2.275)
Because the maxspeed tag applies to all vehicles except overridden for a
specific vehicle type or a conditional, specifying only maxspeed=50 in
any of the above cases has to be considered wrong or at least
incomplete. In other words, the tags you see above would need to be
added in the case the speed limit is given explicitly. It is not so
straightforward then anymore.
So, maybe not for Germany, but as you see, in other places, this *is*
specialist knowledge. No regular car driver in Punjab will be able to
enumerate all these maxspeed rules. And, taking a less extreme example,
I think the Polish OSM contributors wouldn't want to add this
maxspeed:conditional=60 @ (23:00-05:00) to every single unsigned street
in urban areas.
Also, note this is only the urban speed limit, trust me, the default
speed limit "for all other roads" (=rural) can be much more complex.
Actually, don't trust me, see for yourself in the document I link all
the time in the hope people would read it:
We can not get to any results or any progress on the matter of default
speed limits (or for any topic, for that matter) if everyone just keeps
arguing out of his best knowledge about his home region or country only.
"It works for me" is simply not good enough for a global project.
On 22/09/2018 01:03, Martin Koppenhoefer wrote:
> sent from a phone
>> On 19. Sep 2018, at 21:16, Tobias Zwick <osm at westnordost.de> wrote:
>> This is a good argument against tagging an explicit maxspeed=X when
>> there is actually no speed limit sign around (X is what the OSM mapper
>> by his knowledge about the law thinks should be the default limit here).
> everything that you map will be according to your understanding of it, I cannot see a good argument for not tagging implicit limits, even more as there is judgement needed based on the situation (something humans can do much better than computers). Every holder of a driving license should have the requisites to recognize the speed limit on a given piece of road in their local area, so it doesn’t require specialist knowledge.
> We already have a reliable way to distinguish implicit from explicit limits (we even have several of them), if you want to treat them differently in your app, you can do it.
> There actually is a speed limit on most roads, including those without explicit signage. Omitting it will leave us in the situation that it really becomes unclear whether there is no sign or nobody has bothered to enter it.
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