I’ve been mapping the National Cycling Network around Thirsk and the signs on the ground don’t match the routes on the Sustrans website (www.sustrans.org.uk). The area is just north of YO7 1AU.
For instance, Route 657 is shown as going Northwestwards from South Kilvington to join Route 65 but this is not as it is signposted on the ground. The signpost indicates that 65 is 3 miles away but 657 itself seems to stop at that point.
The Sustrans map also shows route 71 but I couldn’t see any indication of this on the ground.
What should I do? Duplicate what the Sustrans website has or show what’s actually there? Would there be a copyright problem to take Sustrans’ version?
Mapping (or even cycling) the NCN can take a bit of ‘interpolation’, though, as the signs can sometimes be erratic! In the example you’ve quoted I don’t think there’s any other way that 657 could go - all the other roads from South Kilvington look too major to route an NCN route along. But I don’t know the area.
OSM does of course have a presumption against copying from other maps. In this particular case I think Sustrans wouldn’t mind, but there’s the possibility of some residual copyright by the Ordnance Survey and they can be very aggressive. So best not to copy.