[Talk-GB] National speed limit changes

[SomeoneElse]

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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