[OSM-talk] road classes

Richard Fairhurst richard at systemeD.net
Fri May 26 15:54:48 BST 2006

Lars wrote:

> Are Collins Bartholomew maps in these scales in general considered
> useful and accurate?  Or do they often make unexpected omissions?

I only know about the UK maps at this scale, I'm afraid, but:

There are certainly some mistakes: it's just taken me 60 seconds  
scrolling around the UK to find two. (A road south of Lichfield is  
mistakenly classed as A38, and the declassified B4544 in Aston  
Clinton, Bucks, is still labelled as such.)

The positional accuracy can be way out, far, far beyond what  
generalisation might demand. I used the same Bartholomew dataset for  
the mapping at Waterscape.com, which has (OS-derived) canal lines  
superimposed, and it's sometimes embarrassing how much the  
superimposed lines don't tally with the canal lines on the Bartholomew  
rasters. (To be fair, this level of positional accuracy is not  
remotely a concern for the target users of such a map.)

But omissions? I'm struggling to find any. On average, I'd say the  
Bartholomew maps at that scale make a better job of selecting which  
roads to include, and which not, than the Google Maps at a comparable  


More information about the talk mailing list