# How to map a square connected to a road correctly?

I’ve seen some cases in which roads are interrupted by a square. The square itself is used as a road, so passengers can pass it. But I wonder if additionally a road has be be mapped across this square to make this area routable.

I found this example (ID 37637216):
Narzissenweg, 89129 Langenau, Germany

Could anyone please tell me if the polygon of the square is sufficient for a proper routing even though there are no roads crossing the square? GraphHopper finds a way on http://www.openstreetmap.org/directions to cross the square by foot while Mapzen doesn’t.

Regards
Holger

Routers being able to find a way across is different from whether it is correctly mapped. In my view, drawing a road across an area, when no physical road is wrong. However, I believe that most routers have problems with areas, which has led to a proliferation of phantom roads and footpaths, rather than better routers.

On the other hand your example is wrong for other reasons, as the roads and paths do not join it such that their centre line is on the corner of the square. What seems to have happened here is that the square has been drawn under-sized to achieve this. As a result the joining roads and paths are too long, and, in the case of the one on the North West corner, an angled section has been added that doesn’t exist in reality.

It isn’t actually clear from the Bing imagery, that this is an open square. There are designs that could be footpaths and gardens, that haven’t been mapped. On the other hand, it might just be the result of a mosaic in the surface.

Incidentally, there is quite a severe imagery offset relative to Bing, and Bing is usually quite well georeferenced these days.

Thanks for your explanations. I can perfectly understand your point of view, distinguishing squares from roads and not doing a wrong here to get some other stuff working properly.

So am I right with my conclusion your statement

is telling me: There is no official guideline how to deal with cases like this?

There may well be official guidelines, but I hope they don’t conflict with the high level guide line: Do Not Tag for the Renderer (where routers are also renderers): http://wiki.openstreetmap.org/wiki/Tagging_for_the_renderer

Searching finds this article that say don’t map the phantom road: https://help.openstreetmap.org/questions/41857/how-to-properly-map-this-situation-square-and-stairs

off-topic, but I like to comment on this statement:

Since Bing’s large scale updates half a year ago or so many of the new images are severely off the correct position.

If vehicles are allowed to pass across the square, I would think the portion of the sqare they drive on can have it’s centreline marked as a way and have it’s surface described too. If the vehicles do not normally follow a particular line of travel, then I would not mark but I would likely add access tags to the square to show what is permitted.
However, I would defer to a general concensus as this situation is very rare in my experience.