[Tagging] Primary or Trunk?

Jonathan bigfatfrog67 at gmail.com
Sun Nov 3 19:07:28 UTC 2013

Sorry if I've not seen the old posts on this, the wiki pages are 
contradictory which is why I asked the question.

In the UK we are defining Trunk or Primary based on some arbitrary 
definition not on anything that is of use to any user or renderer.

What we should be mapping is reality, so that people can use that data 
to build on.  Whether a road is signed in Green, Pink or Purple tells a 
user nothing, it may have a legal definition but that is all.  The tag 
we give it should tell the user something about the road's capabilities, 
importance, size and potential timings/traffic flow.  A Trunk road that 
is a dual carriageway with a maxspeed of 70 mph is very different to a 
Trunk road that winds around fields and has a maxspeed of 50 mph or less!



On 03/11/2013 00:14, Tom Hughes wrote:
> On 02/11/13 18:47, Jonathan wrote:
>> I'm not clear with the distinction of a Trunk road in the UK. The wiki
>> suggests a trunk road is "high performance roads that don't meet the
>> requirement for highway
>> <http://wiki.openstreetmap.org/wiki/Key:highway>=motorway
>> <http://wiki.openstreetmap.org/wiki/Tag:highway%3Dmotorway>" which to me
>> would suggest an A road that is a dual carriageway.  Further on in the
>> wiki it says that any A road in the UK  signed with "Green" signs is a
>> "Trunk" road.
>> I know of many "Green" "A" roads that aren't much more than country
>> lanes, they are definitely not "high performance" and I don't feel they
>> should be "Trunk" roads, I feel they should be "Primary" roads.
> It's really very simple, and has been discussed here many, many times 
> before and I'm sure there are multiple pages on the wiki covering it.
> First, forget the question of which roads are formally designated as 
> trunk roads by the Department for Transport (which is not very many 
> these days).
> Second, understand that there is something called the Primary Route 
> Network defined by DfT which covers those A roads connecting specific 
> major towns. Those are the A roads with the green signs, and are what 
> we tag as highway=trunk. Other A roads are highway=primary.
> In many cases those will be major roads, often ex trunk roads, but in 
> more rural areas like the highlands they might look more like a B road 
> does in other parts of the country. That is irrelevant though.
> In the UK it is really only residential/unclassified/tertiary where 
> you need to make a judgement call. Everything else has a well defined 
> mapping:
>   Motorways => highway=motorway
>   Green Signed A Roads => highway=trunk
>   White Signed A Roads => highway=primary
>   B Roads => highway=secondary
> Hopefully that will explain everything ;-)
> Tom

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