I am sure most of you have noticed that there is something missing in the London underground map (September 09 edition) or at least that there is something different in it. If not, please take some minutes and look at it below:
Well, yes, the Thames -the entire river!- has been removed from the tube map. Weird, isn’t it? The more I keep thinking about it, the more I wonder why…
I did a quick research about it (articles, online newspapers, blogs), and apparently TFL wanted to delete all irrelevant information from the tube map to make it simpler because it was too complex and has become too cluttered (in simple words, that it had too much information).
So, I asked myself the following question: can a river (in the case of London the only natural landmark) be considered as irrelevant information in both colloquial and technical languages? For me, it was hard to find arguments to support positive answers to this question.
Moreover, London is a city that constantly refers to the Thames in different ways and people usually speak about the city as in two halves: over the river (north) and under the river (south). For both Londoners and tourists the river is an undeniable reference point and a key navigation device.
In this post, I am not going to discuss further why the Thames cannot be removed from the London tube map, but I do want to point out that this was not the best solution for the problem of complexity. Even more, if they have argued that tube map had too many elements, why they added an extra reference code box on the right bottom corner, instead of keeping all the reference information together in the right column?
And, was so useless the tariff zone information to be also removed? Now, will people know how much is their journey fare?
I know that the mapping information issue is not easy. However it is essential to know the difference between visual simplicity in terms of visual elements, and visual simplicity in terms of content and information. That means that not because of having less visual elements a diagram is less complex. The key point is to understand exactly which is the additional information in terms of content and what can be removed without the main purpose of a specific diagram being distorted.
Hopefully, in the December 09 tube map edition, the Thames will be back.
Bridging Theory and Practice 
I agree with your point of view!!!!
Visual simplicity implies rational comprehension. What confused ideas have those who decided to remove the “North” of London!!!!
Congratulations!!