[Tagging] Signal-controlled roundabouts

[Bryan Housel]

We have a bunch of roundabouts and traffic circles here in NJ.  Today I learned that roundabouts and traffic circles are not necessarily the same thing.

http://en.wikipedia.org/wiki/Roundabout
- no traffic signals controlling access to the roundabout
- circling traffic in the roundabout has right of way

http://en.wikipedia.org/wiki/Traffic_circle
- access is controlled by traffic signals / stop signs
- right of way can be assigned to circling or entering traffic (there is no set rule)

Maybe an extreme example, this thing is not too far from where I live:
  http://www.openstreetmap.org/#map=18/40.57574/-74.62931
It has a name and some history: 
  http://en.wikipedia.org/wiki/Somerville_Circle
(It is currently tagged junction=roundabout in OSM.)



On Jun 17, 2014, at 4:10 PM, Paul Johnson <baloo at ursamundi.org> wrote:

> Not as rare as you think, and growing more common.  I go through 2 or 3 roundabouts regularly.  The US official definitions defined in the MUTCD are that roundabouts are uncontrolled or have yield signs entering, traffic circles have stop signs.  Neither are signal controlled in the MUTCD.  We do not have anything equivalent to the mini roundabout in the US (and likely Canada, Puerto Rico, Guam, and the US Virgin Islands) at all, so intersections tagged as such are probably wrong.
> 
> On Jun 13, 2014 11:30 AM, "Clay Smalley" <claysmalley at gmail.com> wrote:
> Coming from the US where any form of roundabout is rare, I would consider any circular intersection a roundabout. Some have signals, some don't have signals. I know that some people in the US distinguish between the two, where a 'roundabout' has no signals and a 'traffic circle' does have signals. Either way, it makes sense to me to tag it as a roundabout because:
> 
> 1) it is a junction of multiple roads
> 2) all traffic must enter a circular roadway, and then get off at some point
> 
> Out of curiosity, what are others' criteria for a roundabout?
> 
> 
> On Fri, Jun 13, 2014 at 8:54 AM, Fernando Trebien <fernando.trebien at gmail.com> wrote:
> Hello,
> 
> I used to believe that, by definition, all roundabouts have free
> transit and right of way along the circle, and that anything that
> didn't display that property isn't a roundabout (just a circle). But
> reading the wiki once again, I'm a little in doubt. The wiki mentions
> that this is a roundabout, but I would previously have thought it
> wasn't because of the traffic lights within it:
> http://www.openstreetmap.org/#map=19/52.59689/-1.14146
> 
> So why is it a roundabout? Is it because of the circular shape? Or
> could it be because it's impossible to infer that any of the entering
> ways have right of way, since they are all controlled by traffic
> lights?
> 
> --
> Fernando Trebien
> +55 (51) 9962-5409
> 
> "Nullius in verba."
> 
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