The perfect transit map is a slippery creature. A scale model of the world is terrible for navigation, with twisty intersecting train lines and stations names competing with their neighbors. A hybrid, hewing to reality but cleaning up irregularities—like the current, standard NYC subway map—risks being deceptive. "A map that pretends to be geographical but isn’t quite correct is potentially misleading, implying to people greater distances than exist in reality," says Max Roberts, a map critic and mapmaker based in the U.K. "The more geographical a map looks, the more people might be fooled into taking its distortions literally."
Finally, at the other end of the spectrum, are maps that are less "map" than diagram—representing the network rather than reality. This is what Roberts had in mind with his "circle maps" for New York City and London: diagrams that transform cities’ transit systems into a series of concentric circles.
In his book on subway maps, Roberts scores alternatives based on simplicity, coherence, balance, harmony, and avoiding geographic distortion. "These circles maps score poorly for simplicity: the line trajectories have lots of twists and turns, but score well for coherence: the city is forced into an unprecedented level of organization," says Roberts. It’s clearly geographically distorted, but for this map that’s not part of the goal (and the current subway map is the same way, Manhattan is not actually that wide when compared to Brooklyn). "It’s not trying to show where the network is," says Roberts. "It’s trying to show how the elements of the network relate to each other."
As those network relations become clear through better organization, and map becomes diagram, it may actually become easier to navigate. Later this year, Roberts plans to put this prospect to the real-world test with usability studies.
But regardless of navigational usability, there’s a practical value to being new and eye-catching. "If a map is striking and people like to look at it, then this is half the battle won for a designer," says Roberts. "It makes people less likely to give up and ask a computer for help instead."
The domain of visually striking transit maps is much bigger than circles. Once you throw out geography, the world is your design palette. "My ambition is to create a periodic table of maps, different cities and different rules, systematically exploring each city for each of the possibilities," says Roberts. "That way, I hope to understand how network structure and design rules interact to create a usable (or less usable map)." For New York City alone, he envisions creating at least 10 different maps.
Even among circles, the possibilities are endless, with a new map for any chosen center (not all of them useful). In the case of New York City, Roberts picked a point in the ocean, halfway between Liberty Island and Governor’s Island. "If I had chosen a center higher up (Canal Street station complex was my first hunch) then the lines in the north of Queens might have been straighter, but mid and Lower Manhattan would have been nasty," says Roberts. "This would be a lovely project for graphic design students: give each one a different center and see what they come up with!"