Usability of London's Tube Map

A colleague of mine just got back from London, where use of "the tubes" (subway) is highly encouraged. As a newbie to the system, she relied heavily on the tube map to get around.



She had good things to say about this map (it's aesthetically pleasing, it's easy to use). But her biggest complaint was that she could not tell that a certain destination was going to be twice as far as the last one.

Not being one to take a challenge lying down, I thought about it. The map crams a lot of information into a fairly small space (the image above is reduced a lot). It is fairly information rich. What could be added to that map that would still preserve its aesthetics and simplicity?

How about we give up our preconception that every map has only one scale? (A scale is a ratio of say map miles to real inches of map distance.) What if a map had multiple scales? What if it had a variable scale? Could we present a solution that would service both users who want to get real distances and those who want relative?

Here is what I came up with. Suppose that we put tick marks on the tracks. Each tick mark would represent a distance (say 2 km). This would be true for the whole map. This would allow users to quickly eyeball a source and a destination and either visually compare or actually count the distance. Notice that the actual map inches for each tick is variable. Check out a small section that I blew up and modified.


I think the idea is ready for usability testing! ;-)