Peter Miller wrote:
Correct. I did however use alternative maxspeed:type at times which
also appears in the DB and which I feel is better than source:maxspeed
which to my mind should be used for 'source:maxspeed=survey' or
'source:maxspeed=local authority spreadsheet-Dec12' or similar.
However... lets leave that discussion to another day but either way
not information has been lost by my edits and the data has been made
more consistent.
The problem with e.g. "source:maxspeed = uk:nsl_single" is exactly as
you describe it - it doesn't actually describe the source of the
maxspeed, merely its type. For example, in this case:
http://www.openstreetmap.org/browse/way/135256609/history
"source:maxspeed = sign at E" would be correct, rather than as currently
tagged. If I want to add that bit of information, I now can't.
In terms of UK maxspeed tagging, according to taginfo there are around
10k UK "source:maxspeed=UK:nsl_single" or similar values, and around 5k
instances of "maxspeed:type" - both relatively large numbers. The
largest number of "source:maxspeed" is still "sign".
Presumably the argument for tagging "maxspeed=60mph" where it's actually
signed as "national" is that it's too hard for routers to figure out
whether something's a single or dual carriageway? I'm not sure why we
have to depart from the "on-the-ground" rule in this case - if it's not
obvious that something's a dual carriageway surely that's a tag that
should be added, not some curious code value stored against a tag
(source:maxspeed) that's usually used for something else entirely?
With that in mind, I don't personally see a problem with "national" -
After all, there are certainly plenty of other speed limits that aren't
a nice number - UK motorways with active traffic management, French
motorways when it's raining, and (according to the wiki) German iving
streets.
The other issue, of course, is how long "UK:nsl_single" (or
GB:nsl_single, which is also used) will continue to be meaningful; it
wouldn't surprise me to see different "national" single carriageway
limits in Scotland or Wales within 3-5 years.
Cheers,
Andy
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