New MapRoulette challenge: Lane Counts

MapRoulette is overdue for a new challenge, and we have one that should keep us busy for a while: adding numbers of lanes to the main roads in N-America. This information would be great to have for advanced visualization and transportation analysis purposes. And a lot of it is already there, so let’s just make it complete.

The challenge works as follows: You fire up MapRoulette as usual by going to You are presented with one OSM way somewhere in North America that does not have a lanes=* tag. (We only care about secondary and higher to keep things useful and manageable, and we’re starting with the motorways and moving down, so you should see only motorways at first.)

Screen Shot 2013-04-06 at 1.26.55 PM

If you want to fix this road, click on ‘Edit in JOSM’ and wait for the way to load in JOSM. Make sure you have JOSM running, otherwise the button won’t work.

Screen Shot 2013-04-06 at 1.30.26 PM

To actually see the number of lanes of this road, you may need to zoom in a little.

Screen Shot 2013-04-06 at 1.32.36 PM

Aha! This road has two lanes. So we go ahead and add that as a tag to the road. Hit Alt-A (Option-A on a Mac) or click ‘Add’ in the Properties pane:

And enter the information in the tag dialog:

Screen Shot 2013-04-06 at 1.49.03 PM

Click OK.

Now upload your change, adding a brief changeset comment in which you should mention you used MapRoulette – for example by adding #maproulette:

Then, return to MapRoulette and indicate that you have fixed the problem!


Not all cases are this simple. There’s a few things you need to look out for.

In some cases where the amount of data to load into JOSM would become too big, JOSM will only load the actual way that requires your attention, not the data for the entire area.

Here’s an example:

Screen Shot 2013-04-06 at 2.11.59 PM

If you zoom in and deselect the road, you can see that this road is marked as oneway.

Screen Shot 2013-04-06 at 2.16.46 PM

Because this looks like a dual carriageway road from the aerial imagery, there is probably another OSM way representing the other side of this road. If unsure, confirm by loading more data.

In these cases where only the actual way is loaded, you should also avoid moving or deleting nodes from the way, as these nodes may be shared with other ways you cannot see. Before you make any such changes, load more data.

Also, only enter the number of travel lanes and do not include merge lanes. Here’s an example:


Screen Shot 2013-04-11 at 3.58.11 PMThe right lane is a merge lane, and does not count towards the main road lane count. So in this case the way would get lanes=3. You can see that it’s a merge lane by looking at the context (pan around and you will see the ramp) as well as by the difference in lane markings.



15 thoughts on “New MapRoulette challenge: Lane Counts

  1. Is there any way to limit maproulette to a specific geographical area? I could see this program being very useful for mapping parties, especially with editors with local knowledge of the area.

    1. I know, this is one of the most requested features! In the near future, this will be possible. We are currently working on the next version which will include this and other new features. Stay tuned!

  2. The example you gave has 4 physical lanes and would typically be mapped as lanes=4. The lanes count is normally all travel lanes, including merge lanes and turn lanes.

    1. The assumption was that there would be a motorway_link way parallel that holds the merge lane and would be tagged with lanes=1. If there is no such motorway_link, only then would you map this as lanes=4, if you ask me.

  3. I’m under the impression that pretty much all fixable highways already have been fixed. I’ve clicked through 25 or 30 different spots and each time there was no usable hi-res imagery or the road was still under construction. Do you have a way of removing those unfixable ones?

    1. Hmm let me look into this. I simplified the backend a little to release all ‘touched but not done’ after an hour, but I will see if I filter out the ones that have been looked at but not fixed twice or more, for example

    2. I think I fixed this, by allowing folks to flag something as unfixable. If two people do this, that particular problem won’t be served up anymore. Hope that helps.

  4. I am not seeing the “Edit in Potlatch” option now, only “Skip” or JOSM. It would be great, at least for a challenge like this with easy answers, if you could show the imagery and just ask for an answer in MapRoulette without even going to an editor. (When I tried to display the imagery in a similar way, I ran into cross-site scripting trouble, so I realize it may not be easy.)

  5. Yay, down to 0! Are there any new Roulettes in the works? The weather is getting worse and I could use some new couchmapping tasks 🙂

    1. These are just random ideas:
      * Highways without a surface tag.
      * Highways without tiger:split=yes and FIXME:dual-carriageway
      * Nodes with amenity:school. Break these out to areas.

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