Recently, on reddit, someone linked to a map of the US interstate system laid out “subway style.” Rather than including all the geographical features of the United States, the artist opted to realign everything on a relatively simple aligned grid, emphasizing the purpose of the system (“get me from here to there”) rather than the implementation (“via this bridge over this river, using this exit by this town”). The artist himself complains tongue-in-cheek about the complexity of the existing system:

You know, the Interstate System is a pretty incredible bit of infrastructure, but have you ever looked at a map? It’s all over the place! Did those civil engineers never hear of a ruler?

Perhaps such a map is a nice idea in practice, but in the name of becoming simple, the map loses so much information that it becomes nearly worthless. The elimination of any sense of scale leaves you no idea how long it will take to get between two points. The absence of any geographical information means you have no idea what conditions or weather you may encounter. The elimination of intermediate place-names means that you cannot get to a location not on the map, no matter how close it may be to places that are on the map, unless you already know the complex system that the simplified layout is trying to hide. In an attempt to isolate the reader from the complexity of the Interstate, the map has given up an overwhelming amount of what made that same Interstate useful to begin with.

This whole discussion may seem like an aimless rant. After all, no one is seriously proposing to replace our normal Interstate maps with this simplified design. Yet such systems already dominate major mass transit maps. Take a look at the maps for the Chicago “L”, the DC Metro, or the T in Boston. The maps all list place names, but street names and major landmarks are completely missing (except for the Loop insert on the Chicago map), and times can vary tremendously. (Stops on the DC map, for example, go from at least one minute to about five with no indication, and relative distances on the map can be horribly misleading. Judging by the map, Foggy Bottom to Court House should be the same time as Metro Center to Farragut North, with both among the longest inter-station travel times in the system. That’s not even close to being correct.)

The New York Subway map is better in some ways and worse than some ways than Chicago, Boston, and DC. Taking advantage of the fact that most parts of the city are on grid systems, the map emphasizes intersections over place names. Although the map still lacks any meaningful scale, the grid system is simple enough that even a newcomer to the city, with a minute or two instruction, could make at least a rough guess for travel times—at least in Manhattan north of Houston. Even here, though, the map falls short. If someone wants to get to downtown Manhattan or one of the outer boroughs, they’re stuck. The map does not include enough information to make rational decisions without consulting an additional, detailed, scale map, just as with the other systems.

Now take a look at onnyturf’s map of the New York Subway. The subways and their stops still stand out and are easy to find, but now the entire map is to scale. The lines no longer run graceful curves; instead, the small blips and squiggles of long-forgotten zoning fights and long-gone support pillars for defunct skyscrapers are there for all the eye to see. Yet, if anything, the map has actually become easier to use. Someone completely new to the New York Subway could make a decent guess about how to get from one point to another, even if he were trying to get to a place not on the official New York Subway map. The added complexity actually simplifies the utility.

Simplicity is a good thing, but the focus should always be on simplicity for the user, not of the item itself. Sometimes, making something simple to involves exposing its warts.