[talk-au] Unclassified Highway Speeds

Dian Ågesson me at diacritic.xyz
Wed Apr 20 04:55:22 UTC 2022



Hey Andrew,

I'm chiming in as I encountered this issue documenting the "cleaned up" 
Roads tagging guidelines. 
(https://wiki.openstreetmap.org/wiki/Australian_Tagging_Guidelines/Roads)

The tagging guidelines (both prior to, and following cleanup) state it 
is good practice in Australia to tag every road with a maxspeed.

The early guidelines say that the implicit speed limits have not been 
widely adopted in Australia, but this no longer appears to be true.

In use is both the maxspeed:type tag and source:maxspeed tag. 
Unfortunately, the earlier guidelines offers advice on the usage of the 
source:maxspeed tag that is contradictory to the global page. (It 
suggests local_knowledge to mark implicit speed limits rather than 
AU:urban). The maxspeed:type tag does not have this contradiction.

I am not sure if leaving the maxspeed blank (or using a non-numeric 
value) would be a good idea; using a non numeric value in maxspeed seems 
to be much less preferred globally than the alternative methods. I 
documented maxspeed:type rather than source:maxspeed following a discord 
discussion, but I believe either of those two schemes are preferable to 
using maxspeed=AU:urban.

Dian

On 2022-04-20 13:45, Andrew Hughes wrote:

> Hi All,
> 
> First, I thought the tagging guidelines were "don't tag unless it's a 
> non-default value" (my language to describe this might be inaccurate, 
> feel free to improve). If this is true, then I shouldn't tag rural ALL 
> roads with  maxspeed. It's only those that are "non-default".
> 
> Can anyone please confirm the above please?
> 
> Secondly, it does look like there is a tagging for implicit (speed) 
> values as per  
> https://wiki.openstreetmap.org/wiki/Key:maxspeed#Implicit_maxspeed_values 
>  [1]
> maxspeed = AU:urban
> maxspeed = AU:rural
> 
> I believe that the above is better than tagging 50kph, 60kph or 100kph 
> - because a change in legislation (as has happened in the past) can 
> change is without tags needing to be updated.
> 
> But that all being said, I would still be tagging all roads and not 
> just those that are "non-default" on the ground. Which contradicts the 
> first point (if it is true that is).
> 
> This feels like a distinct gap in OSM (as others have pointed out). But 
> this is one I would like to know how to deal with.
> 
> Perhaps area's could be tagged with maxspeed=AU:urban or 
> maxspeed=AU:rural  to define "implicit speed areas"? I think this might 
> be what is missing. Thoughts?
> 
> Thanks for reading
> AH
> 
> On Wed, 20 Apr 2022 at 10:30, Graeme Fitzpatrick 
> <graemefitz1 at gmail.com> wrote:
> 
>> In regard to defaults, the default 50kph Qld (Oz-wide?) urban 
>> residential limit should apply around here, & sure enough, most 
>> streets are 50. But we also have some residential streets posted as 
>> 40, 60 & 70, as well as 40 conditional school zones.
>> 
>> So I assume (using that terrible word! :-)) that actually tagging a 
>> speed limit on a road overrides the default?
>> 
>> & while I've seen reference to Default Qld Residential speed limit on 
>> the map, I've also noticed while driving around that OSMAND isn't 
>> showing a speed limit?
>> 
>> Thanks
>> 
>> Graeme
>> _______________________________________________
>> Talk-au mailing list
>> Talk-au at openstreetmap.org
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> 
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Links:
------
[1] 
https://wiki.openstreetmap.org/wiki/Key:maxspeed#Implicit_maxspeed_values
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