[Talk-GB] Turn Restrictions at roundabouts

Edward Bainton bainton.ete at gmail.com
Sun Oct 4 06:42:19 UTC 2020


I regularly get QA messages about this when I use the "ImproveOSM" in iD -
just about every roundabout near me has at least one.

I've been marking them as false positives as to my mind it's obvious that
you wouldn't U-turn there (but equally, it would be legal to do so).

But the points about machine routing make me think maybe I shouldn't be
closing these off? Any thoughts?

Eg, at node https://www.openstreetmap.org/node/26187838

Missing Turn Restriction
Description
0 of 326 recorded trips (travelling west) make a turn from Bretton
Gate to Bretton
Gate at this node. There may be a missing "no_right_turn" restriction.




On Sat, 3 Oct 2020 at 20:01, James Derrick <lists at jamesderrick.org> wrote:

> Hi Dave,
>
> Thanks for answering my original router logic question! :-)
>
>
> On 03/10/2020 17:52, Dave F via Talk-GB wrote:
> > I've just tested in JOSM. It flagged no such validation warning.
> > https://www.openstreetmap.org/way/3403352
>
> Interesting - you're right, I couldn't easily reproduce the 'Sharp
> Angle' validation warning in the latest JOSM either.
>
> After hunting out the code, the warning currently isn't triggered unless
> the segment leading to a <45deg angle is <10m:
>
> https://josm.openstreetmap.de/browser/josm/trunk/src/org/openstreetmap/josm/data/validation/tests/SharpAngles.java
>
> Looking at a couple of local roundabouts via imagery, a flare this short
> verges on a single node highway=mini_roundabout, unless lots of extra
> nodes have been added to the flare to give a curved approach.
>
> After over a dozen years of using JOSM, it still surprises me with extra
> features.
>
> Happy Mapping,
>
>
> James
> --
> James Derrick
>      lists at jamesderrick.org, Cramlington, England
>      I wouldn't be a volunteer if you paid me...
>      https://www.openstreetmap.org/user/James%20Derrick
>
>
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