[Talk-GB] Mapping turn lanes on major roads

SomeoneElse lists at mail.atownsend.org.uk
Fri Nov 7 23:42:24 UTC 2014

I'd always assumed that the correct way to map turn lanes is via:

http://wiki.openstreetmap.org/wiki/Key:turn:lanes .

However, some mappers in the UK* have started mapping each individual 
lane as a separate parallel road.  Here's an example:


That note was obviously written from the point of view that mapping a 
single carriageway road as one way with appropriate turn lanes tags is 
"correct"; whether it is or not is the question that I'm asking here.

So - should we map a dual carriageway as two parallel roads and a single 
carriageway as one (with appropriate turn lanes) or is it equally valid 
(or even perhaps better) to map each turn lane as a separate parallel 
road, even if there's nothing but a broken line of paint between them?

I'm trying to get some idea of concensus here because obviously it'd be 
wrong for me to go back to another mapper and say "you're not doing it 
correctly" if there isn't a concensus about the best way to do it, or 
the concensus is that what they're doing is at least equally valid.



* and this isn't a question about just one mapper - I've seen a few 
people do it.  The example junction on the A17 just happens to be one 
that I spotted today (and a junction that I'm familiar with from walking 
that section of the Viking Way).

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