can someone pls show me on osm the best example of an elevated highway. i’m not sure of the best practice how to draw the way when the roads are directly above the ones on the ground.
here is a pic of what i’m referring to
Guess nobody knows what’s the best example. Neither do I.
As usual in OSM I just draw lines at the center line of each highway. For dual carriage ways two lines, the highway is physically separated as in the photo. The upper highway gets bridge=viaduct and layer=1 or higher. Here’s an example in Bangkok on the bilingual map with zoom level 19. It shows the begin of the bridge. In Bangkok you can find many other examples. It never happened to me that the center lines of lower and upper highway were at the same position. In this case I would introduce a small offset of about one meter.
I agree. I think drawing the 2 highways one over another (using the same nodes) is not a good idea.
Drawing both ways over each other is correct if they run parallel (horizonticaly 
), but not using the same nodes (just if there is a connection from the upper to the lower highway at this nodes).
Yes, so you would shift the 2 node-rows:
Line 1 :
------X------X------X------X------
Line 2 (over Line 1):
–X------X------X------X------X–
(X= Node)
Because, Double-Nodes are considered as error by some tools.
i understand not using the same nodes for the 2 levels as they are both separate roads.
sounds like a silly question… if i place the layer1 road directly on top of the layer0 road, how do i select the layer0 road in future edits? do i have to move the layer1 road everytime i was to access layer0?
Depends on the editor you use.
In JOSM for example you can click several times on the line with the middle mouse button. With
each click another line is selected.
any similar trick in potlatch?
Select the shared node, press / .
thanks but thats for shared nodes. this example is for 2 roads on top of each other but do not intersect, so both have separate nodes. guess i’ll offset them as suggested earlier. thanks all for ur input