Currently I am at a workshop in Dagstuhl about Drawing Maps and Graphs with Curves. Part of this workshop is the exhibition Bending Reality: Where arc and science meet, which is, well, about drawings of maps and graphs with curved edges. I will write about the exhibition in a different post. Today I concentrate on a series of beautiful drawings of metro network maps by Maxwell J. Roberts, which were shown at the exhibition. Max also gave an interesting talk about the ideas and the motivation behind his drawings. Often one has to distinguish between artistic design criteria and usability. I am mostly interested in these drawings as art, and there were quite a few exceptional drawings presented.
Since the workshop is about curved arcs, also most of the metro maps were using curved edges, quite to the contrary to the prominent octolinear design rule. Here is an example of the network map of Paris. The network in Paris is one of the densest in the world. At the first glimpse I thought that the curved version is a bit chaotic due to the absence of parallel lines. However I find it absolutely plausible, that it is easier to navigate compared to the official Paris map. Maybe most important, the ring formed by the lines 2 and 6 is not very visible in the official map, whereas it is the crucial feature in the curved map. Max claimed that people can navigate on the curved map 50% faster. Still half of the people would prefer the traditional map.
In contrast to the Paris map there were a few very recent maps with a drawing style called concentric drawing. These maps might not be the best for navigating, but they are absolutely stunning. The idea is to route all lines either on a set of concentric circles, or an a set of rays emanating from the circles' center. By this you get nice 90° crossings. Of course you have to diverge from the design rule at some places if you have a complicated network. Below you can see the maps of Madrid and Berlin. Funny fact about Berlin: the station at the center is called "Stadtmitte", which translates to "city centre". Despite the name, the station is rather small and somehow in the middle of nowhere. So at least the location in the concentric layout justifies the name. Alternative maps from Berlin can be found here.
If you are interested in more information you can have a look at Max' website. Here you can order prints of the maps or you can purchase Max' book about metro network (I had the chance to have a look at the book, it covers the historical developments in the metro map business as well as design criteria. Great book!).
By coincidence today's xkcd comic was about metro maps. I especially like the idea of having an extension of Boston's green line to Canada.