Some of you may have noticed that I added a "missing" column to http://qa.poole.ch/ch-roads/ end of last year, this is the difference between the total number of objects in the GWR list (with a house number) and the matches found in OSM for the municipality (1).
As an anniversary project and proof of concept, over the last couple of weeks I've systematically gone through the list and have added missing streets and street names, and other place objects (mainly farms) for the Canton Aargau by using the localisation provided by the addresses from the GWR http://qa.poole.ch/addresses/ch/ to as far as possible determine the correct names and add anything that is missing.
Back in 2014 I had already lifted the street names up to nearly complete by cycling to these places and checking in person, so I was already starting at a fairly high level, and actually most of the missing roads were new developments. On the area like objects one of the main issues I noticed was that, while lots of these had been mapped as landuse=farmyard and in many cases already had the correct names, but were missing a place=farm, further when addresses were present they often were using addr:street instead of addr:place to reference the place (2).
In any case the net result is that of a total of 20'030 entries we now only have 41 missing, that is a 99.8% match ratio, this is better than say for Solothurn where the street data was originally imported and any other canton (the absolute difference in Basel-Stadt is smaller, but they have a factor 10 less roads). The 41 missing are typically either streets where the geometry is unclear, objects missing from the address data, or other issues with the address data, in some cases it just needs another check. For example there is a road missing in Mumpf which likely does really exist, but will need an on the ground survey to determine where it actually is as it might be partially covered.
Simon
(1) One of the noticeable issues with the current GWR data, particularly since the update last fall is that we have a lot more systematic spelling differences, in particular Genève seems to have changed their capitalisation policy which creates a lot of "false positives" in an area in which we previously had very good matches. I'm not proposing that anything should be done in these cases for now, at least not before we get to the bottom of it (if they've flipped one way, they might flip back next time, just as the weird issue in FR where roads are currently being declared as area objects). The matching criteria are deliberately strict to highlight such differences, but in practical terms they shouldn't have an impact in day to day use.
(2) Even in the same canton there are large differences how municipalities treat farms and similar settlements, some will assign proper house numbers, some don't, some do actually name the roads others don't googlefy things.