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https://openstreetmap.org/copyright | https://openstreetmap.org |
Copyright OpenStreetMap and contributors, under an open license |
Surveyed today, and on Glenway I only saw the one at Hillcrest and Hammersley. Both those were already mapped as mini_roundabout. Based on the documentation in the wiki, I don't think they qualify and should instead be tagged as traffic_calming=island. I retagged accordingly (there may be many more wrongly tagged islands in Madison). Feel free to reopen if you disagree.
From my understanding, a traffic island would refer to a short part of a road that is dual-carriageway. I don't believe that a mini-roundabout would be accurate, either, because how substantial the islands are.
I discussed with some other OSM folks on the OSM-US slack channel. Best thing we could come up with: Draw the circle as a circle with junction=roundabout, then add the two stop signs on the approaches from the side street. What do you think?
I'm curious however y'all decide (I'm indifferent about the topic) as I've mapped a few of these around town in various ways and would like to have a consistent method :)
I think part of the problem is that they're not all the same. This intersection for example has a "keep right" sign on Glenway (https://en.wikipedia.org/wiki/Road_signs_in_the_United_States#/media/File:MUTCD_R4-7.svg). So if you want to turn left onto Hillcrest you theoretically have to go around the circle. A majority of the other ones in town don't have that sign and you can make a straight left. Interestingly, OSRM routing has a way of distinguishing these "roundabout intersections" and give routing instructions accordingly ("turn left on Hillcrest" instead of "take the third exit to Hillcrest") https://github.com/Project-OSRM/osrm-backend/pull/2718
I feel it would be best to draw it as a circle and tag it as junction=roundabout since you would need to enter and exit the circle in order to turn or go straight. This method would be more informative for anyone using the data. Also, sorry for not responding- I rarely check the email my account uses (we really should also be getting notifications on this site for note comments/changes and changeset comments).
Could you find an example of an intersection that would allow you to make a straight left?
Here's an example of one I've seen--whether the turn is legal or not, I'm not sure http://ethan-nelson.github.io/misc/traffic_calming.jpg.