Last month, we released the Missing Roads plugin and web tool. This quickly became a popular pastime for quite a few mappers - one month later, more than 20% of all the Missing Road tiles have already been resolved :)
For the darker and colder November days -- well, if you are on the Northern hemisphere at least -- we thought we would cook up something new to keep us all busy. We ran another analysis on our GPS data to uncover ways that probably do not have the right directionality. Either they should be
oneway=yes and they are not, or they are
oneway=yes but in the wrong direction.
Here is an example from Karlsruhe, Germany:
The orange arrow points in the direction we think traffic on that street flows based on what we know from our Scout GPS data.
The way we do this is by looking at the directionality of the GPS tracks. If more than, say, 90% of all tracks matched to an OSM way go in a single direction, it is pretty safe to assume that it is a one-way street. We then compare that to how the way is mapped in OSM. If there is no correct
oneway tag on the way, you will see the way in this tool.
Let's open the earlier example up in JOSM:
This looks a bit cluttered because there is so much OSM data, but if we zoom in a bit and make the OSM data layer invisible for a moment, we can see from the direction the cars are parked and the arrows on the road that this is indeed a one-way street:
Aerial imagery in JOSM from Bing
We found more than 140.000 (!) of these cases all over the world waiting for us to fix them. This works almost exactly the same as in our Missing Roads plugin and web tool we released last month. You can look at the Missing Roads manual. (I will write a proper manual for the One-way plugin and tool soon.)
Here is the address for the web tool: http://improve-osm.org/trafficFlowDirection. You can find the JOSM plugin in the JOSM plugin preferences. The source code for the plugin is on Github as always. We started a wiki page for the plugin as well.
Happy mapping and please, as always, let me know what you think :)