[talk-au] Unclassified Highway Speeds

[Andrew Hughes]

Thank you all for your contributions to this thread so far, much
appreciated!

*Please correct me if you disagree with this...*
1. So it would seem that ALL roads should be tagged with maxspeed and
assigned a numeric value (kph), where the maxspeed is known.
2. Supplementary to #1. the maxspeed:type tag also adds information of
value because it can indicate if the maxspeed is "signed" or on the basis
of it being unsigned and relative to its geographical ("AU:Urban" or
"AU:rural") location.

*Important question...*
The guidelines also suggest that the use of maxspeed = "AU:Urban" or
"AU:rural" without a maxspeed tag could indicate that this has not been
surveyed. Adding this tag (with these values) without a maxspeed is also
encouraged as it improves the data such that the maxspeed can be assumed
with far greater accuracy (50pkh/60kph NT or 100kph), and loosely indicates
the survey status.

Cheers,
AH


On Thu, 21 Apr 2022 at 11:36, Andrew Harvey <andrew.harvey4 at gmail.com>
wrote:

>
>
> On Wed, 20 Apr 2022 at 14:58, Dian Ågesson <me at diacritic.xyz> wrote:
>
>> 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.
>>
> I would agree that it's good practice to tag every road with a maxspeed.
> https://wiki.openstreetmap.org/wiki/Good_practice#Don.27t_map_local_legislation_if_not_bound_to_specific_objects does
> seem to confirm that. Generally being more specific with your tagging
> especially when confirmed on the ground is better.
>
> Similar for surface=asphalt, it used to be the case that you wouldn't
> bother tagging this as you assume it was the case if no surface was tagged,
> but to improve data quality and to distinguish this from "yet to be
> surveyed", and with the rise of editors like iD which give you an explicit
> dropdown or checkbox and StreetComplete which asks for every feature and
> needs an explicit tag to know it's been checked on the ground, it's more
> acceptable to always tag.
>
>
>> 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.
>>
>
> I think those are useful in addition to the maxspeed tag, as they indicate
> if the maxspeed value came from a signpost/road marking, or due to implied
> legal defaults eg in NSW residential roads are 50km/h unless otherwise
> signposted.
>
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