[Tagging] Motorway_junction = javbw confusion

[John Willis]

Javbw
> On Jun 2, 2016, at 7:59 AM, Duane Gearhart <duane at mapzen.com> wrote:
> 
> Can you give an example route using osm.org of where there is an issue?

I will re-read the tagging pages to make sure I am not confused, but if a "motorway_junction" = exit, and there is no implicit tag for entrances, this works fine in most places because there is usually a entrance-exit pair for each direction of travel. 

I assume because the ways are connected with a shared node that routing software can tell where to turn and where to go, but since the junction is used as a rendered label of the intersection, that visually might be confusing if there is an exit/entrance only in one direction on the motorway or if there is an entrance only. 

In the freeway system of America, the entrances and exits will be 4 separate motorway_links that separately leave a normal road to join the motorway, but that is not expected in Japan - a single entrance-exit intersection for all directions of travel is common - so having a separated entrance or a junction with an exit for only one direction of travel is rendered confusingly. I have also come across junctions with named sections (gate 1&2)  handling their own entrance and exit _links under the guise of being a single "junction". 

Common Japanese Junction.
https://www.openstreetmap.org/#map=16/36.2414/138.8943

Common US underpass Junction 
https://www.openstreetmap.org/#map=17/32.93673/-117.11117

Orphaned US entrance. 
https://www.openstreetmap.org/#map=19/32.72472/-117.15108 
(This is for 163 north, entrance on the other side is for 5 south or 94 west) 

Separated Japanese Junction (etc only, causes wrong way drivers because of separation) 
https://www.openstreetmap.org/#map=15/36.3073/139.0912

Japanese Exit only southbound (C22). Entrance only northbound. (Orphaned exit & orphaned entrance)This was the junction that had me question why the entrance _link had a junction tag on it. 

The tollway is in a tunnel under the primary road. 

https://www.openstreetmap.org/#map=16/35.6639/139.6882

Weird junction that has 2 "gates" that lead to different major roads to go to two different tourist attractions (Mt Fuji & Hakone Caldera) but all under the same junction name and reference (ref=7) instead of the normal separation of close junctions (ref=7 & ref=7-1) 

https://www.openstreetmap.org/#map=15/35.2952/138.9500




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