Re: [Tagging] waterway highway

[André Pirard]

On 2013-08-10 10:12, Friedrich Volkmann wrote : On 08.08.2013 11:10, Martin Koppenhoefer wrote: Can I have waterway=dam highway=* you could, but I'd suggest to use distinct objects and add layer tags to one in order to define stacking. I think that one single object should suffice as long as the dam and the road don't have different names or something. We don't make separate objects for highway=* and embankment=* either. However, I am afraid that some renderers are too dumb to extract a highway and a dam out of one object. That makes your suggestion seem fine from a practical viewpoint. There are bridges with a pipeline inside and a footway on top (or an underground railway inside and a road on top). In that case, we should definitely separate them in order to define layer=*. It is important to duplicate the nodes too because the pipeline is not connected to the footway (as opposed to the road which is connected to the dam). If we would care, even the nodes should get layer=* tags. I think that we should have a single object per way or node because it would be ambiguous to which object an attribute tag applies (and it's not a reason that there are no attributes to make an exception). But, before that, we should know which tags define objects and the wiki gives no such definitions. Some people even say that it's unimportant and that it's a point of view.  Not the best way to make a uniform database. BTW, to the suggestion I got here to draw my waterway = dam as a rectangle, Osmose didn't miss the occasion to say that it's a circular river.  Same for waterway = river, lock = yes This confirms my amazement that such objects are called waterways and not simply dam and lock. I have tried an inventive area = yes. Shouldn't the wiki prescribe that to make the distinction between "bigger" and "smaller"? I'm glad that you mention bridges with a footway on top because I noticed that many bridges have a road on top, but that OSM puts them on top of the road. Despite they are at different layers, the OSM map splits the road to make a bogus interruption into which the cars fall and over which routers must jump when they notice that the route passes under a bridge. I wrote to this list a message titled SEGMENT saying almost the same thing as you say, but beyond. The roads (any way) should not be split but segments of additional way should be created on top, like lengths of adhesive tape, containing the tags to be added to a span of the mother way. Segments are applicable for roads being partially one-way, speed limited, ... and many situations. The advantage is particularly apparent when mapping a hike that splits the roads everywhere, and especially a main road over 20 m because the paths the hike follows are not facing each other exactly when crossing the road. Not only a piece of segment sticked over that 20 m could avoid a split, but using segments for the whole of the hike would have spared any split and a relation in the first place. Cheers, André.

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