Just over a year ago I started running daily street name completeness checks for Switzerland based on a list of street names by municipality generated out of the federal “Gebäude und Wohnungsregister” (GWR), see my original article for more information and http://qa.poole.ch/ch-roads/ for the daily updates.
For technical reasons I decided to move the contents to a new server late December and during the process I’ve made a couple of updates and changes that need some explaining. On the one hand I’ve updated the GWR list to the December 2013 one on the other hand I’ve somewhat changed the logic of the road (contrary to other object types with names) statistic generation. One of the more annoying trends in the GWR list is that more and more municipalities are no longer correctly filing the object type in their submissions and are either using “unknown” or leaving the field empty (which I map to “none” in my statistics”), despite the large amount of building going on, the number has actually gone down in absolute terms by roughly 500 over the year 2013. This naturally makes the data substantially less useful for us, and I would go as far as saying it makes the data less useful for its primary purpose too.
However it is clearly not our job to discipline such behaviour, we just want as good as possible estimates of how many named streets there actually are. To achieve that I’ve now added some heuristics to take this undesirable behaviour in to account:
- assume that if a GWR object has either no geometry type or “unknown” and the corresponding OSM object is a road, it should have been a road in the GWR too.
- if there are no roads at all for the municipality in question in the GWR and OSM has roads as described above, add all the relevant GWR objects to the GWR road count.
The GWR numbers reported are corrected correspondingly. As of today this reduced the object count for “unknown” by 8’374 and for no object type by 4’438, adding a total of 12’812 to the GWR road count. For continuity and documentation purposes the old statistics are still calculated daily and are still available.
More interesting than the above changes is how much progress we have made over the past year. In the following table non-road objects are summarised in one number.
|GWR 2012-06-01||OSM 2012-11-01||%||GWR 2013-12-01||OSM 2013-12-27||%|
As can be seen from the above we managed to add 20’024 names in just over a year, confirming that we should have as good as possible coverage of street names latest in two years.
To conclude, and most impressive, a map from early 2013, and current versions using the old and new logic
December 2013 Old
December 2013 New