[Tagging] Turn Lane Tagging?

Tijmen Stam mailinglists at iivq.net
Sat Jun 11 21:11:58 UTC 2016


On 11-06-16 04:16, James Mast wrote:
> I've been using the "turn:lanes:*=none;slight_right" &
> "slight_left;none" tags to indicate which side a new lane has been added
> on a highway when going from 1 to 2 lanes (sometimes
> "slight_left;slight_right" if the original lane is centered between the
> two new lanes).  How else are people to properly identify which side the
> new lane is being added to?

NOO!

That's what the transit:-tag is for: 
<https://wiki.openstreetmap.org/wiki/Proposed_features/transit>

All lanes and road attributes that I know of are neatly summed up - not 
on the OSM wiki but the JOSM wiki: 
<https://josm.openstreetmap.de/wiki/Styles/Lane_and_Road_Attributes>. 
 From there links point to the OSM wiki.

Take a look at this way (
> https://www.openstreetmap.org/way/419799887 ) and take a look at the
> Bing imagery and look at the 'turn:lanes:forward' tag, and you'll see
> how this can, and would be valid.

The way I see it, the only "turn:lane" markers that signify a lane 
change is merge_with_left/merge_with_right. All the others signify that 
you can choose between different ways!

The way I think this should be tagged is:
no turn:lanes
transit:lanes:forward=continue;new_on_left
(the continue is optional in this case).

See for example Way 415775038
Which has one lane, but the next segment has two lanes (one through lane 
and a right turn lane)
"transit:lanes"="continue;new_on_right"
(Note that this is not a good example: the Bing image isn't current and 
the lane will be changed next monday, so I'll probably update it tuesday 
evening)

It's allowing the router to know that
> a new lane is being added when combined with the next way (
> https://www.openstreetmap.org/way/419799886 ) which has the
> "lanes:forward=2" tag.  It also allows the routers to properly tell
> people to get in the left lane if just ahead, there's a left turn they
> need to make.

OSMand already does that with proper turn:lanes. It gives a 
preannouncement of which lanes you should go to:
<https://dl.dropboxusercontent.com/u/240848/OSM/Screenshot_2015-11-23-20-36-55.png>
(The arrows are yellow before you are on the way, and green if you are 
on the way that has the turn:lanes)

As far as I know, OSMand doesn't use transit:lanes.
BTW, the "Lanes and road attribute" mappaint style doesn't use the 
transit:lanes for rendering, but it does a check on them, giving a 
warning if an incorrect transit:lanes is used.

Tijmen



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