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

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1

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?

2

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:

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image754×575 51 KB

https://www.openstreetmap.org/#map=19/52.36082/5.61890

Or man_made=bridge + waterway=+bridge=

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https://www.openstreetmap.org/#map=19/51.97199/4.60267

The problem is that natural=water does not render above man_made=bridge:
https://www.openstreetmap.org/way/638876602

3

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

1 Like
4

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

5

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=

6

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

7

I mean that a waterway has a line:
https://www.openstreetmap.org/way/32485988

and an area:
https://www.openstreetmap.org/way/44866444

I would recommend where the bridge start to have a waterway line with bridge=aqueduct + layer=
https://www.openstreetmap.org/way/39979931

and an area of natural=water+layer= :
https://www.openstreetmap.org/way/638876602

to represent the area of water inside the bridge

I would do only at the bridge

8

Thanks, I just tried something as per your advice.

9

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 https://www.openstreetmap.org/#map=18/52.69425/-2.18957

1 Like
10

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

11

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.

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

12

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).