[Tagging] Carriageway divider

Tobias Knerr osm at tobias-knerr.de
Sun Aug 19 17:23:57 BST 2012

On 19.08.2012 15:09, Markus Lindholm wrote:
> On 19 August 2012 14:49, Fabrizio Carrai <fabrizio.carrai at gmail.com> wrote:
>> This could be a solution but it is against the reality: this kind of road
>> are indeed a single entity. The "legal" division, i.e. the "solid_line" is
>> just an attribute.
> There's a multitude of cases where a single entity is represented by
> multiple objects in the database, e.g. when the road changes speed
> limit it has to be split into two highway objects. The same with bus
> routes, to accommodate then the road was to be split into many parts.

A major difference is that it is comparatively easy to re-assemble a way
that has been split (because they have common nodes).

It's not so easy with two parallel ways that somehow "belong together" -
the connection could only be established by rather complex heuristics
based on proximity among other things. In practice, it would simply
result in gaps or overlaps appearing randomly depending how "parallel"
the mapper has actually drawn the ways, and on the width assumed (or
tagged) for the ways.

I clearly prefer the divider attribute, especially because could be
combined with Lanes tagging[1] to model the dividers between lanes for
the same direction, too, not just the central divider.


[1] http://wiki.openstreetmap.org/wiki/Lanes

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