About every six months, ITO process road name data published from the UK Ordnance Survey and run a comparison against OSM. This is an interesting time as the differences show up new building sites you didn't know existed and are prime for survey.
The ITO service is not the only tool that does this, but I like the colour coding and overall view of both the UK as a whole, and individual differences.
The comparison also shows up fat-fingered mistakes, but don't assume OSM mappers are any better or worse than the professionals - OS data feeds from local authorities don't always match the 'ground truth' signage actually on the ground!
In particular, this means don't blindly accept the OS Locator data is correct and add a 'source:name=OS Locator' tag, particularly if OSM is marked source=survey. Take the time for a ground survey, and if there's no signage out there to contradict or correct, then an attributed name from OS is better than none. If Locator is wrong, use the tag 'not:name=' to show the issue to comparison sites like ITO, and also to OS so they can check themselves.
The indeterminate cases are harder - North Tyneside has a street with four signs on walls next to each other saying both 'EDWINS AVENUE' and 'EDWIN'S AVENUE'. As the apostrophe signage is newer, I've added it to the highway, with alt_name for the version without as the 'ground truth' really is both versions!
Looking at my local areas, Wansbeck had a couple of additions which are already surveyed so will update to a 100% match in a few days. Blyth Valley survey locations will be an easy cycle tomorrow to Seaton Delaval, leaving Castle Morpeth and North Tyneside to catch up over the next few weeks.
It is interesting watching the statistics tick closer and closer to 100% as local mappers fix issues, only for the stats to go back down in 6 months. Still, the whole of the UK is only just under 98% in agreement with OS (including where we agree to disagree) so not only is OSM comprehensive, it is keeping up with changes over time.
So, raise a glass to ITO for the service, and the local groups of fellow mappers! You will see the number of differences reduce sharply over the next few weeks as GPSr are turned on and notebooks written in.
Help turn all UK counties UK cyan on the overview map - a 100% match!