Submitted by Nick, who says:

I’ve been following your blog for a little while now and have really enjoyed your posts on transit maps – both familiar and completely new to me. I’ve recently become interested in different ways of looking at maps from a data standpoint. I’ve attached a screenshot of a project I just released that I thought you or your readers may enjoy. It’s not a map or diagram but it’s a data visualization based on the colors used in all the official rapid transit diagrams from around the world and where they are on a global spectrum of colors.

Transit Maps says:

Quite simply, this is phenomenal work. Seeing how route colours are used by transit maps around the world is absolutely fascinating, and the number of ways that Nick presents the data is astounding. As a designer, I can see that this could be an invaluable tool for creating a colour palette for maps, although I wish that the charts included the RGB or Hex values for each colour for easy reference. I could easily lose track of time exploring this!

Source: Nick’s Global Subway Spectrum website