[OSM-talk] Country Specific Route Markers

Richard Fairhurst richard at systemeD.net
Wed Aug 15 10:25:29 BST 2007

Tom Hughes wrote:

> To some extent it does happen in the UK. At the very least you can
> have the A414 == NCN1 case for example (true in Harlow). I know that
> is currently hacked round with the ncn_ref tag, but that is rather
> more UK specific that seems entirely reasonable.

Yes, and in Europe (including the UK, but we don't sign it), lots of  
major roads also have a Euroroute number: E14 or whatever.

We do have the general problem that you can't tie one "route" to a  
particular "ref", which as you say is hacked around with ncn_ref, and  
I believe things like the network tag are meant to solve. The solution  
is probably to agree on the network tag or something similar. :)

(FWIW I'm coming to the conclusion that the mooted rewrite of  
Potlatch's tag editing panel will have to abstract away a lot of the  
underlying tags, just like Potlatch abstracts away segments. The  
tagging vocabulary is getting too big, and the rules too complex, for  
the first-timer.)

> Not to mention cases where one road "runs under" another - those are
> normally ignored in the UK and signs would normally only show the more
> senior road, but I think it does technically happen.

Strictly speaking I believe a UK road can actually only have one ref.

On (say) the A14 south of Kettering, both the A43 and A6 share its  
course for a while (people at sabre-roads call this "multiplexing").  
But the road is legally just the A14, it's not the A43 or A6 as well.


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