[Tagging] Proper Tag for Not-a-Roundabout

Daniel Hofmann hofmann at mapbox.com
Tue Nov 8 11:07:24 UTC 2016


In the second example "Skalitzer Straße" has right of way.

Here are the instructions emitted at the moment:
http://www.openstreetmap.org/directions?engine=osrm_car&route=52.49915%2C13.41952%3B52.49857%2C13.41852#map=19/52.49896/13.41865

it's a total of four turn instructions every 10-20 meter since there is no
proper tag for the routing engine to differentiate this from a road with
four intersections.
Instead the routing engine could emit a single instruction here.

My argument is this: there already is a pseudo tag for these
Not-a-Roundabouts:
it's 1/ no junction=roundabout tag and 2/ a note tag containing
"roundabout" / "Kreisverkehr"

Here's an example:
http://overpass-turbo.eu/s/jTV

querying for (junction!=roundabout) and (note~"roundabout|Kreisverkehr")

The routing engine could do the same parsing note tags.
This would allow us to classify probably all popular ones at least.

But it's a hack and that's exactly my point: there should be a proper
tagging scheme to tag this.

On Mon, Nov 7, 2016 at 5:09 PM, Dave F <davefoxfac63 at btinternet.com> wrote:

> Hi Daniel
>
> Second example: Which junction has priority? From a quick look on
> Streetview all junctions appear to be light controlled.
>
> Could you expand on what 'special instructions' the routing engine is not
> able to issue?
>
> DaveF
>
>
> On 07/11/2016 14:30, Daniel Hofmann wrote:
>
> Over at OSRM we're not only doing Routing on OSM but also Guidance for
> users once a suitable route is found. In order to make the user experience
> great and the instructions pleasant to use we differentiate between
>
> 1/ Roundabouts
> Think: "at the roundabout take the nth exit"
>
> 2/ Roundabout Intersections
> These are roundabouts with up to four ways and turn angles which makes the
> turns obvious.
> Think: "at the roundabout turn left"
>
> 3/ Rotaries
> These are large and named roundabouts.
> Think: "at Meinplatz take the nth exit"
>
> 4/ Not-a-Roundabout (what this post is about)
> There are situations where one of the entering road has right of way,
> which disqualifies the scenario for being classified as a roundabout. The
> Wiki has a section on these Not-a-Roundabouts:
>
> http://wiki.openstreetmap.org/wiki/Tag:junction%
> 3Droundabout#Not_a_roundabout
> > In all these cases, the key “junction” is not necessary at all. You need
> no special tagging.
>
> Most of these Not-a-Roundabouts have a note on them, telling users not to
> tag them as junction=roundabout as this is a common mistake. Here are two
> examples in Berlin:
>
> Bersarinplatz
>
> http://www.openstreetmap.org/way/288767318#map=19/52.51849/
> 13.45355&layers=D
>
> http://www.openstreetmap.org/directions?engine=osrm_car&
> route=52.51786%2C13.45348%3B52.51918%2C13.45281#map=19/52.51852/13.45327
>
> Kottbusser Tor
>
> http://www.openstreetmap.org/way/159155852#map=19/52.49898/
> 13.41881&layers=D
>
> http://www.openstreetmap.org/directions?engine=osrm_car&
> route=52.49915%2C13.41952%3B52.49857%2C13.41852#map=19/52.49896/13.41865
>
> As you can tell, for both of those situations the routing engine is not
> able to issue special instructions since there is no tag to parse. And
> parsing note tags for the occurrence of roundabout is not a solution ;)
>
> With the current situations of having note="don't tag as roundabout"
> pseudo-tags on most of those it would make sense to establish a proper
> junction=not_a_roundabout tag (tag is up for discussion) software can parse
> and make use of.
>
> What's your opinion on Not-a-Roundabout?
>
> Cheers,
> Daniel J H
>
>
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