[Talk-GB] National speed limit changes

[Richard Mann]

IIRC a lot of those tags were added by Chriscf, without any local
surveying, and since the value was derived from the speed limit, there's
little added value in having separate maxspeed:type values. It's just
clutter. What matters to the data user is the maxspeed tag. The
maxspeed:type tag is probably only of use to mappers. And not much use to
them either.


On Tue, Sep 24, 2013 at 2:26 PM, SomeoneElse <lists at mail.atownsend.org.uk>wrote:

>  Hi Peter,
>
> Thanks for replying here.
>
> Peter Miller wrote:
>
>
>  So...on the basis that we should tag what is there, we see a white sign
> with a black diagonal line on it then that is what we should indicate. We
> do of course interpret that by putting what we believe if the correct legal
> speed limit in maxspeed. As such a single carriageway national limit is
> coded as "maxspeed:type=gb:national,maxspeed=60 mph". As dual carriageway
> is tagged as "maxspeed:type=gb:national,maxspeed=70 mph". The motorway
> version is "highway=motorway,maxspeed:type=gb:national,maxspeed=70 mph".
>
>
> I understand the potential problem (does a national speed limit dual
> carriageway slip road count as a dual carriageway or not?) but am concerned
> that changing e.g. "GB:nsl_single" to "gb:national" will:
>
> o potentially obscure any underlying data errors (imagine something tagged
> "maxspeed=70 mph, maxspeed:type=GB:nsl_single")
>
> o make things more difficult for data consumers (if only by changing the
> data from something that they might be expecting)
>
> o confuse new mappers who see data that they've entered being changed
> because it's "wrong", when in reality there really isn't a concensus on
> this.
>
> I fully accept that national speed limit tagging in the UK is a mess (at
> the time of writing 4 of the top 6 values for
> http://taginfo.openstreetmap.org.uk/keys/maxspeed:type#values could mean
> the same thing) but any consolidation must proceed following discussion.
>
> With regard to the other point:
>
> For avoidance of doubt, all my edits have been fully manual.
>
>
> I don't believe that anyone has suggested otherwise, although I have
> certainly suggested that you may not have visited all of the places that
> you have been changing the speed limit for.  There is clearly a sliding
> scale between "I've surveyed an area, and everything that I've edited is
> based on the results of that survey, aided by e.g. Bing, OSSV, and other
> named sources" and "I've changed a bunch of tags worldwide based on who
> knows what information without even looking where I've changed them".
>
> The wiki's "mechanical edit policy<http://wiki.openstreetmap.org/wiki/Mechanical_Edit_Policy>"
> (as currently written) suggests that changes of this type may be covered
> ("search-and-replace operations using an editor... unless your changes are
> backed up by knowledge or survey") - I guess that it depends on what you
> mean by "knowledge" **.
>
> Clearly no-one's going to object to some tag-changing edits
> (designation=public_fooptath to designation=public_footpath for example)
> but in this case there's enough doubt - other mappers have said "I think
> the changes should reverted" and "This tag is vital" in the replies to my
> original mail.
>
> Based on that, where you've changed e.g. "GB:nsl_single" to "gb:national"
> would it be possible for you to revert your changes?  There's clearly a
> discussion to be had going forward about which one of GB:blah, UK:blah,
> gb:blah and uk:blah we need to keep, but based on the replies so far there
> doesn't appear to be a concensus to support merging of everything into
> "gb:national".
>
> Cheers,
>
> Andy
>
> ** In which case quite possibly mea culpa for the changesets that I refer
> to here<https://lists.openstreetmap.org/pipermail/talk-gb/2013-September/015227.html>- it's not black and white.
>
>
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