How to map a river in a bridge above a road?

Hi, fellow mappers.

How would you map a river flowing in a bridge above a highway such as this particular example?

Would you do it in an other way?

Hello Pan,

There seems to be two ways of mapping aqueducts, ether by making the road underneath a tunnel and adding natural=water+name=* on top. Without a man_made=bridge:

Or man_made=bridge + waterway=+bridge=

The problem is that natural=water does not render above man_made=bridge:

This is an aqueduct, rather than just a bridge, so the tagging of the part carrying the water should be tagged as bridge=aqueduct.

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Thank you. This is what I did, I think. The problem, then, is in the renderer, I guess.

The problem is that if you want to render natural=water above man_made=bridge that many other bridges won’t look right. However, I do recommend that you add an natual=water area with the correct layer=

I am not sure I understand. The reverbank is a rather large relation. Do you suggest applying the layer tag top the complete relation?

I mean that a waterway has a line:

and an area:

I would recommend where the bridge start to have a waterway line with bridge=aqueduct + layer=

and an area of natural=water+layer= :

to represent the area of water inside the bridge

I would do only at the bridge

Thanks, I just tried something as per your advice.

It’s not a bridge, it’s an aqueduct. Same word in french.

If you tag as bridge=aqueduct the water will render above the road, for example

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Thanks. I had both tags (man_made=bridge and bridge=aqueduct). I removed the first one.

If you really, really really insist on having your water mapped as an area at layer 1 and rendered, take the bridge area away. Fear though then the roads below will wade through. (try-al and error ;P)

The main reason I map bridge areas is because a bridge with mapped sidewalks, cycleway, north and southbound separated by double guardrails and suspension cables looks ludicrous over land and water.

(an engineering marvel how this one was constructed, sadly never found a fast forward image compilation, if it was ever made.)

It’s perfectly OK to map the bridge structure as man_made=bridge as well, like here. Different renderers will handle that in different ways (here is one example).