[Tagging] Feature Proposal - Voting - lanes General Extension
imagic.osm at gmail.com
Tue Mar 6 08:07:39 GMT 2012
> 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.
My point was, that no matter how this is solved (left/right or
forward/backward) one application type has a problem. And as we
shouldn't make any decisions based on application priority ("we don't
map for routers/renderers") this results in a tie for both approaches.
So the decision should be based on something else. After some
discussions this lead me to the following:
1) The objective part: How is it done currently? Take a look at my
first example in the proposal - it's using maxspeed. How is maxspeed
currently tagged? According to the wiki maxspeed:forward and
maxspeed:backward should be used. What tells use taginfo? The
forward/backward variant is used more than 7000 times, the right/left
about 50 times. What are the access rules using? Forward/Backward.
What is used: lanes:forward/backward or lanes:left/right? The first
about 3400 times, the latter about 250. The first is also documented
in the wiki.
When is left/right used at all? According to taginfo :right is used in
name:right, is_in:right and parking:lanes:right (these are the first
three). They all describe what happens next to(!) the carriageway, but
not on it.
Seems like a clear point for forward/backward.
2) The subjective part: the objective part tells us how it is done,
but this still might be bad. In such cases I'll ask my belly ;-) What
ways will most likely be tagged with lane information? Ways with
lanes! (Wow!) What kind of ways are those? Footways? Not really.
Cycleways? Yeah - seen a few of them, but very, very seldom. Ski
slopes? Nope! Streets - the one with those crazy cars? This seems more
like it. How do I (remember: subjective) think of the lanes running in
different directions? Left and right lanes or forward and backward
lanes? Clearly the second. So my (completely subjective) belly
confirms the objective part.
That's why I went for the forward/backward approach.
I also think that we should clearly separate those approaches:
backward/forward for the directions of the ways/lanes and right/left
for anything next to the ways. This would be consistent. At least in
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