In message ,
at 20:28:53 on Thu, 28 Oct 2004, Tom Anderson
remarked:
But how do you know whether a map is accurate? That you can evaluate them
implies that you have some sort of authoritative source of knowledge about
the routes - which is what i'm after!

Maps like that have to be pieced together from a wide range of sources.
For example, the W&C map I posted a link to. An earlier in the year
there was a long discussion about the approaches to Morden (another
place where there's been a "joining the dots" rather than accurately
depicting the route). I've got some other original maps of the Northern
as it crosses the Thames. Others have spoken of the Piccadilly near
South Ken, and the Jubilee north of Baker St being formerly Bakerloo
makes the right-angle crossing shown rather implausible. I don't see a
huge bend at Bank-Central, which one observes when on the train. And so
on. Lots of little things to put together, each of which will improve
one small part.
--
Roland Perry