OpenStreetMap
I just noticed that a huge section of NCN national route 75 has disappeared. There's a note on the OpenStreetMap data (added by user Mappo?) that says "closed due to reopening of railway line. Due to be replaced with new route by 2010". I guess it has something to do with this Airdrie-Bathgate Rail Link, which I've never heard of before. I'm not quite sure exactly why Edinburgh needs a fourth rail link to Glasgow (that takes 24 minutes longer than the existing 50 minute train) but it brings up an interesting question - given that every cycle map apart from OpenStreetMap will show NCN75 as being complete, people looking here will automatically assume that OSM is incomplete... maybe some alternative rendering for closed routes would be appropriate.
Discussion
Comment from Richard on 24 November 2008 at 06:43
http://www.airdriebathgateraillink.co.uk/faq has lots more. From the FAQ it doesn't seem that the route is all necessarily closing instantly. I'd be tempted to keep it tagged for the time being but with a note/description tag.
Comment from Andy Allan on 24 November 2008 at 10:51
I'd definitely leave it in there, there's a whole state = proposed concept that can easily be extended to state = closed or whatever.
Comment from Mappo on 24 November 2008 at 11:28
Hi, that was me. We're not the only cycle map with a big gap now, as it was when I saw that Sustrans had updated theirs, and announced that the route had closed, that I made the change:
http://www.sustrans.org.uk/default.asp?sID=1095084657765
http://www.sustrans.org.uk/webfiles/map%20updates/Clyde%20to%20Forth%20-%20NN75.pdf
There's slightly more to this though. At zoom level 11 (e.g. your link) it looks like there's a big gap in 75 (which there is), but if you zoom one level further then you can see the cycleway, so it still looks like you can cycle the route, it just isn't an official ncn route.
I marked the closed sections with access=no, which I hoped might be rendered in a way that shows that it isn't simply missing at the high level, and show it's still there, but (apparently) closed. Of course, as well as being a "closed" cycle route, this should also now be marked up as a "proposed" railway line, and a new "proposed" cycle route following a route somewhere alongside it which might complicate things further.
I guess confusing people who compare with paper maps is a general hazard of online mapping. Another change discussed by sustrans is rcn 43 becoming ncn 754. I changed the whole route into a relation so that it can easily be switched whenever it becomes "official" but you're guaranteed to have someone looking for 754 before it changes, and 43 afterwards and assuming we're wrong, because we're not a 'proper' map. Should we transition these things in some way for say 6 months, a year?