[Talk-us] tagging cul-de-sacs

Ian Dees ian.dees at gmail.com
Tue Apr 10 15:52:20 BST 2012

On Tue, Apr 10, 2012 at 9:39 AM, Peter Dobratz <peter at dobratz.us> wrote:

> On Tue, Apr 10, 2012 at 10:17 AM, Martijn van Exel <mvexel at gmail.com>
> wrote:
> > On 4/10/2012 7:46 AM, Peter Dobratz wrote:
> >>
> >> I'm experimenting with the Java code from Traveling Salesman
> >>
> >> http://wiki.openstreetmap.org/wiki/Traveling_salesman
> >>
> >> http://www.openstreetmap.org/browse/way/158307363
> >>
> >> Is this how people generally map these things?
> >
> >
> > No, I ususally tag the end node highway=turning_circle. There are so
> many of
> > them littered around US suburbia that mapping each and every one of them
> as
> > a circular way would make for a lot of not too useful data, not to
> mention a
> > lot of work.
> So we have 2 people in favor of discarding the circular portion of the
> Way and just using a node with highway=turning_circle.  I actually
> also use this approach on roads such as this:
> http://www.openstreetmap.org/browse/way/157338683
> I distinguish between having a solid paved surface and a traffic
> island.  This seems to make sense based on the recommendations for
> dual carriage ways (presence of physical separation causing separate
> Ways).
> According to the wiki:
> http://wiki.openstreetmap.org/wiki/Tag:highway%3Dturning_circle:
> "There is no central island/reservation to a turning circle—it's
> simply a wider bit of road."
> Are you saying that you delete these circular portions of ways and
> replace with a node?

No, I think we're suggesting 3 things:

1) mini_roundabouts (and regular roundabouts) have multiple exits and are
at the junction of many roads. Cul-de-sacs are not mini-roundabouts.
2) When it's a wider bit of road meant to allow vehicles to turn around,
then the last node of the road should be placed in the middle of the area
and be tagged highway=turning_circle.
3) When the cul-de-sac has an island not meant for traffic a loop of way
should go around the island and connect back on itself. Sometimes I become
lazy and will put a turning_circle node in the middle of the island and
break this rule.
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