[OSM-talk] Roundabouts - why is a separate segment required?

Andy Townsend ajt1047 at gmail.com
Wed Feb 14 18:32:54 UTC 2018

(... snip ...)
>>> Technically speaking you are not because you are just touching one 
>>> node of the roundabout.
>> Yes you are. You may not be on there very long, but you approach the
>> roundabout, pass the signs saying it's a roundabout, give way to those
>> already on it, you enter it & then indicate that you're leaving it.
> Not from a data standpoint.

OSM's "lines and points" abstraction is just an abstraction of the real 
world.  In the real world you're on a road, and you're joining the 
roundabout, staying there for a bit and then leaving it again on the 
next road.  Having one exit node not joined to the next entry node 
better represents the real-world situation*.

Best Regards,

* unless you happen to be riding a Spherical Cow along one of those 
"frictionless surfaces" I remember from Applied Maths at school many 
years ago.

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