Roundabouts and divided streets

I apologize if this is a newbie question, I’ve decided I would contribute to OSM and improve Kampala, Uganda while I’m here with my Garmin HCx, a local map, and my spare time so I have a quick question (the first of many no doubt).

I’m using Merkaartor to work on this area in downtown Kampala, but I’m looking at Nile Avenue which is a divided road with a roundabout in the middle of it that merges into an undivided road, so I can’t join the roads together and it’s left with four roads marked at Nile Avenue. It’s accurate, but obviously this is a bad setup. Can a more experience/expert editor guide me on how one works with and improves this?


That looks to me like its mapped correctly (except I presume the individual carriageways are oneway, if so they should be tagged as oneway=yes. And the roundabouts should be tagged as junction=roundabout).

Yes, the map does look a bit ugly with repeated names etc, but that’s a problem with the renderer, and not the data.

There are several proposed relations which might help with this, by grouping the different parts of the road together:
But they are just proposals, I don’t know if any renderers support them.

Hello Rich,

welcome to openstreetmap! As Vclaw said, at the moment there is no better solution to map roads with lanes which are separated for each direction. So you did everything alright. For more information you can have a look at the wiki

In the last weeks I tried to improve the map of kampala by tracing the yahoo aerial images. I hope I did everything alright, but of course I don’t know whether the images were still up to date, and sometimes it is a bit difficult to recognize streets on the images. So if you find that some of my contributions are false, don’t hesitate to correct them.

While working on the map I had the impression that the different tags for the importance of a street (“primary”, “secondary”, “tertiary”, “unclassified” …) are sometimes not consistent. So if you come upon streets you think are tagged wrong, it would be a good thing if you could correct these tags.

One last thing: Apparently there is now a big bypass road north of the center of kampala. On the yahoo images this was not yet build. Do you think you could add it during your stay in kampala?

EDIT: If you intend to add more details like hotels, banks, post offices and so on, the following could be helpful to you:

EDIT2: I hope you don’t mind if I add just two more things:

  1. You write that you use a local map. Maybe you know this already, but please make sure that all your contributions are based on non-copyrighted information. For example it is not permitted to copy street names from a proprietory map to openstreetmap. For more information please refer to

  2. When you added the name to the Lubigi Channel, apparently something went wrong: You joined all single parts of the channel into one, so the “waterway” tag is now ambigous and the whole channel is tagged as “tunnel=yes”. When I traced the channel I tagged the parts of the channel which go underneath roads as “tunnel=yes” because it seemed to me that the water simply goes into some sort of tunnel there (the alternative being that there is a proper bridge for the road). Since I do not want to interfere with your current work there, would you mind having a look into the matter?