[Tagging] Lane dividers

Tobias Knerr osm at tobias-knerr.de
Wed Oct 17 16:21:13 GMT 2012


On 17.10.2012 13:19, Martin Vonwald wrote:
> 2012/10/17 Tobias Knerr <osm at tobias-knerr.de>:
>> This problem does indeed exist, but it only appears with oneway roads
> 
> I don't like something that only works in case a but not in b.

This was merely meant as an interesting observation that I wanted to
point out for those who are still thinking about and playing with
different approaches (as I understand you are, given that you presented
your examples as a "first idea").

A finished solution would of course have to work for both cases.

>>> Now (a time ago) I came up with something different: have a look at
>>> part 3 of the first example:
>>> http://wiki.openstreetmap.org/wiki/User:Imagic/LaneMapping *
>>>
>>> Please keep in mind that's just a first idea! What do you think?
>>
>> That is a very different approach from the divider tag. It amounts to
>> tagging one of the effects of the divider, rather than the divider
>> itself, so there is a lot of information missing.
> 
> Actually we do the same thing when we map a oneway: as was pointed out
> in how-to-map-thread we don't map "there's a blue signpost with a
> white arrow" but instead we map the effect. I also don't see what
> important information is missing.

You can distinguish at most 4 types of dividers with two pairs of yes/no
- but there are a lot more types out there. That's a big part of the
original divider proposal, which even includes values like "dots".
For example, how do you reconstruct the distinction between one or two
solid lines from a "crossing:lanes=...no|no..."? Besides the different
visual appearance, there are also subtly different legal meanings here.

Another possible idea (= not the same as a finished solution) would be
to introduce something like this:

type:divider = solid_line|double_solid_line|dashed_line|kerb

Basically, use the idea of lanes, but a different suffix - and
consequently a different number of values. This has the advantage to
allow multiple tags for a divider (e.g. colour:divider to distinguish
white and yellow markings).

Tobias



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