[Tagging] Feature Proposal - Voting - lanes General Extension

Tobias Knerr osm at tobias-knerr.de
Mon Mar 5 20:44:25 GMT 2012

Martin Vonwald wrote:
> Regarding your comments (which would better fit into the discussion page):

They were more of a footnote, but I'm happy to discuss them anyway. If 
you prefer to have this discussion on the talk page, feel free to copy 
the relevant sections of my mails to it. I don't mind continuing the 
discussion there.

> * Left-Right: [...] The left-right-approach makes it
> very easy for the renderer, but impossible for the router, because the
> router misses the information of the driving direction. The
> forward-backward-approach makes it easy for the router, but the
> renderer doesn't know if the forward-lanes are right or left (and the
> same for the backward-lanes). Both problems disappear as soon as the
> information about left-hand/right-hand traffic is available.

I also consider this, to some degree, a trade-of between routing and 
rendering requirements: No matter which approach you choose, one of the 
application categories will be able to handle basic cases without 
information about left-hand/right-hand traffic, while the other will 
not. It seems we agree so far.

However, routers already need to handle country-specific traffic rules 
anyway (for things like default maxspeeds, implied access rights, and so 
on). This is not usually the case for renderers.

Therefore, wouldn't it make more sense to pick renderers as the 
application category that can make do without left-hand/right-hand 
traffic information? For them, gaining that ability is a qualitative 
benefit. For routers it's just about one more application of the same 
already-implemented concept.


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