[Talk-us] Check your turn:lanes

Paul Johnson baloo at ursamundi.org
Thu Aug 25 16:55:33 UTC 2016

On Thu, Aug 25, 2016 at 11:04 AM, Jack Burke <burkejf3 at gmail.com> wrote:

> Even if the road isn't signed that way?  The use of "through" when there
> is no explicit marking to that effect seems to be contraindicated by the
> wiki.

I'm considering the ground truth in this case to be how the lane can
actually be legally used, since (at least in North America where the
direction of travel is obviated by the yellow centerline) lane arrows are
much less common than in some other parts in the world.  Otherwise most
intersections with turn pockets would end up as none|none|none|none instead
of left|through|through|right.  Low-angle intersections are especially
tricky for routing engines; in absense of anything other than a lane count,
for example, Osmand will "invent" a new lane for the departing ramp
(indicating say, the right most of through|through|through) instead of the
correct through|through;slight_right (with the slight_right highlighted).

> Don't get me wrong--I don't see why we _couldn't_ use it when that is the
> obvious traffic direction, even with the lack of explicit signage.  But if
> that's how we want to use "through" then shouldn't we update the wiki to be
> more clear?

I think the wiki should be updated, yes, since the wiki's not describing
how it's been implemented in the real world right now.  Though, to be fair,
the only consumer I know that's actually doing anything with this data
right now is Osmand.
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