[OSM-newbies] Adding a cul-de-sac to an existing street

[Simon Ward]

On Fri, Aug 20, 2010 at 11:23:43AM +1000, Steve Bennett wrote:
> On Fri, Aug 20, 2010 at 10:51 AM, Richard Weait <richard at weait.com> wrote:
> > OSM expects a 'way' to be either a line, or a simple, closed polygon.
> > Self-crossings, bifurcations and self-intersections other than a
> > simple closed polygon are errors.
> 
> Interesting, I didn't know that. Potlatch behaves badly when dealing
> with self-intersections (ie, a P shape) but I didn't realise that it
> wasn't supported in OSM in general.

Not all self‐intersecting ways are bad.  Take roundabouts for instance.
I have probably mapped P shapes before, too, and not worried about the
way intersecting itself.

Why exactly are self‐intersecting ways so bad as they are made out to
be?

Simon
-- 
A complex system that works is invariably found to have evolved from a
simple system that works.—John Gall
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