The Mini Metros project can trace its origins to my futile attempt to make an iPhone app several years ago. Coding is not my forte, but I had fun designing mockups. One of the things I liked the most were these very simple icons for navigating menus in the app. I liked that the icon for the Washington Metro map was so recognizable, even at such a small size. So I did more.
All of the cities in the project had the same requirements: they had to fit in a 120px circle (with 10px of padding), the lines had to be 3px wide with a minimum of another 3px between the next parallel line, and all diagonals had to be 45-degrees. The systems themselves needed to be full-fledged heavy rail metro systems or light rail networks that were distinct enough from trolleys or streetcars.
There were many cities that were difficult to fit into these requirements, but it was very satisfying creating very complex maps that still resembled their full-size counterparts at very small sizes. Below are the cities that were the most challenging, and how they compare.