[Talk-GB] maxspeed changes

[SomeoneElse]

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