On Tue, Apr 9, 2013 at 9:36 AM, Vladimir Vyskocil < [email protected]> wrote:
> > Relation feature essentially means, "group up some objects to represent as > a feature". > So I think it could suite for our traffic_signal & junction naming, > routing. > (relation could express "label" membership) > > I also agree > I think we need some clean-up in the traffic signals tags/relations anyway. >From its beginning, the tag "highway=traffic_signals" has been designated to say "this intersection is controlled by traffic signals". It did not say which lanes were controlled on which direction. It was not intended to identify each individual traffic signal. Unfortunately, since we have hi-res images available, some contributors are using the same tag to locate exactly each traffic signal next to the intersection. Why not. We are not against improving data quality. But the problem is that they use the same tag, most probably because it is rendered and they just "draw a map". They don't care about the difference "intersection controlled by traffic signals" vs "single traffic light". They don't care if the same intersection is sometimes modeled with one "highway=traffic_signals" or four or eight "highway=traffic_signals" nodes. They don't care if it makes a difference for routing penalties or rendering choices (e.g. zoom levels). Once we decide to accept such level of details, we need to distinguish the two methods of modeling traffic signals. We need a new tag to identify single traffic signals . And we need of course a relation to say which traffic signal belongs to which intersection (like for stops or giveway). Once we have a correct modeling, it will be possible to use the data correctly in applications like routing or rendering at different zoom levels. Note that we have intersections with names and intersections with traffic signals. It does not have to be on the same relation types because it is imho two different features. Pieren
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