OpenStreetMap
I went for a walk photographing street names, then I uploaded the GPS traces for my wife's running routes. When I started to edit the map it raised more questions than it answered, so I'll need to do some more fieldwork.
I noticed that the outline of Williamson Park is very approximate. I'll try to walk the boundary sometime. Also I noticed that the location of the canal where it passes underneath the A6 isn't right. This area needs to be re-worked.
Discussion
Comment from Stead on 15 May 2008 at 17:40
Yea, i've found most of the rivers/railways/major roads seem either quite off, or quite a bit off, have to bend rivers around roads i've mapped sometimes (of course it could just be everything i've mapped is wrong...but I get the impression a lot of the major roads were just imported as with rail links?
Comment from davidearl on 15 May 2008 at 20:17
If waterways have been traced from NPE out-of-copyright maps they can lose 200m accuracy over about 3 or 4km (at least in my eastern part of the UK - I found them better in mid Wales for example), and the lines on them are so wide you couldn't get it accurately to get a bridge say. But trunk roads shouldn't have come from NPE, and as a canal is always accessible, there shouldn't be any problem improviong its accuaracy - except in deep cuttings or lots of overhangling wooded bits that are common on canals where the GPS signal drops out.