Yes, Carto Metro is great - though even it has the odd place where the congestion of overlaid tunnels makes it just possible to miss something. For instance - precisely in the context of this question - the Northern-Piccadilly link at Kings Cross (the sole access to the Northern from any other line, I seem to remember), between the southbound Northern and the northbound Picc, is hidden under the SSL station diagram, and if you don't know what's going on there it might just be possible to misconstrue what's being shown.
There is actually an inset of the Kings Cross area at the top of the map (next to Cheshunt). This shows a larger, detailed version and includes the disused main line connection between the City Widened Lines and the Met / Circle line.
As the CM map is to scale, it is obviously difficult to shown everything clearly where there is a lot going on, especially at KX with the several lines at different levels in a small area (KX is probably the worst area on the map for this). It also helps to zoom right in where an area is particularly congested (1200-2400 magnification is good).
Elsewhere on the map, where there is more space, Franklin has, where necessary, drawn superimposed tracks side by side with a notation stating this. Elsewhere, tracks may have been slightly deviated from the true scale path for clarity.
@Slimjim 1694
I agree that, depending on what level of information is required, it’s better to use more than one source if necessary. By its very nature, the CM map is limited to what it can show historically. As it is a scale map, there just isn’t the space to show all the changes that have occurred over the years without it becoming unreadable in places, especially where there have been many big layout changes.
The map shows some historical information, more out of interest than specifically aiming to show everything. This is especially so on the tube lines where there are usually fewer changes over time than on the main line. Usually where the changes occur, they are often on the parts of the line that originally had main line trains running over them and thus goods yards etc. (many of which are now car parks).
I use the CM maps on a daily basis because it is a quick and easy reference if I want to look something up. However, for local, in depth, information, I will use other sources, such as the London Rail Atlas. The NLS map site is also an excellent source for looking at track layouts, with the large scale Ordnance Survey maps giving great details.
