[Talk-GB] Maxspeed tagging for the UK

Chris Hill osm at raggedred.net
Thu Apr 14 12:27:42 BST 2011

On 14/04/11 11:42, Richard Fairhurst wrote:
> Peter Miller wrote:
> >  So the proposal is now:
>> maxspeed:type=GB:national_single|GB:national_dual|GB:motorway|GB:restricted
> I may be missing the point on all of this, but:
> Why are we doing this?
> In OSM we optimise for the mapper, not the data consumer. That means we tag
> exceptions, not majorities.
> So if you have highway=motorway, the consumer can assume the national speed
> limit applies, which is 70mph; no need for a maxspeed or maxspeed:type tag.
> If you have highway=trunk (or anything down to unclassified), assume the
> national speed limit applies, which is currently 60mph if it's a single
> carriageway, 70mph if it's a dual[1]. And so on.
> Where this isn't true, you put a maxspeed tag on. This works for pretty much
> everything from 30mph on B roads through villages to 50mph on rural A roads
> to 70mph on the A55 Special Road. No need for a maxspeed:type tag at all.
> Have I missed something blindingly obvious?
> cheers
> Richard
> [1] Perhaps the only difficulty is that there's currently no trivial way to
> identify what's a dual carriageway and what isn't, short of doing clever
> geometry stuff. But that's easy to fix: either a relation (spit) or
> preferably something simple like dual_carriageway=yes.

Cheers, Chris
user: chillly

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