[Talk-GB] Maxspeed tagging for the UK

Steve Doerr doerr.stephen at gmail.com
Thu Apr 14 09:59:20 BST 2011

On 14/04/2011 08:21, Peter Miller wrote:
> On 12 April 2011 15:39, Steve Doerr <doerr.stephen at gmail.com 
> <mailto:doerr.stephen at gmail.com>> wrote:
>     On 12/04/2011 15:16, Ed Avis wrote:

>         However, one flaw is that the speed limit sign is not for
>         'dual carriageway
>         limit applies' but rather 'national speed limit applies'.  So
>         we still would not
>         be tagging exactly what appears on the sign, but adding some
>         additional
>         interpretation.  I think that is fair enough, but those who
>         hold to a strict
>         on-the-ground principle may disagree.

>     I was going to make the same point.
>     maxspeed:derivation=national_dual|national_single|motorway|restricted
>     ?

> I think we are getting there. Two points:
> 1) The phase maxspeed:type has already be proposed and is in use in 
> some places. Can I there suggest maxspeed:type rather than 
> maxspeed:derivation. I think that will also be more understandable to 
> people who's first language is not English.
> 2) In place of 'national' can I suggest 'GB:' to fit with 
> international conventions.
> Which brings one to the following:
> maxspeed:type=GB:dual|GB:single|GB:motorway|GB:restricted
But that then negates the point Ed was making and that I was agreeing 
with: that the sign says 'national speed limit applies' for the first 
two. So my suggestion conveys two pieces of information in one tag:

- the road is subject to the national speed limit (because of a sign);
- the road is dual or single as the case may be (because the mapper has 
observed it to be so).

It also preserves explicitly the distinction between the national speed 
limit (60 or 70, special sign) and the 30 mph 'restricted road' limit.

I don't mind 'type' for 'derivation', and the GB: prefix makes sense. I 
believe GB is the ISO code for the UK, not necessarily restricted to 
Great Britain (the British Isles minus the island of Ireland).


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