The Story of Circles Maps
Berlin, the first ever network diagram from 1931
A circle line or some sort of orbital loop occurs in many urban rail networks worldwide, and faced with such a potentially regular feature, many designers have been tempted to emphasise it geometrically as a cornerstone of a network diagram. Berlin was the first on both counts, first circle, first diagram for a full network, but this is only part of the story, because the straight lines on the Berlin diagram are at 'standard angles' (horizontal and straight lines, with diagonals at 45-degrees), two years before being introduced by the city more closely associated with them - London. Mixing circles with 'standard angle' straight lines is never completely satisfactory because, as we will see, it is hard to integrate the two.
Loterie Nationale Paris Metro map of 1936
The Paris Metro is a bit of a 'designers graveyard' in many ways, tempting all sorts of people to attempt solutions that might have seemed a good idea at the time. With Lines 2 and 6 forming an orbital loop, a circle might be a good way to show this. However, with Paris, for typographical and geographical reasons, this can result in a design that is unbalanced, chaotic, or both.
Lebre Paris Metro map of 1975
In both these examples, the designers ended up with straight lines at just about every angle possible, counteracting the organising effect of the circle. The earlier Berlin design was at least orderly, even if circles and the 'standard angles' don't necessarily go together.
Moscow Metro map from 1976 - the stations might have vaulted ceilings, marble, and chandeliers, but the print quality is terrible.
If ever a city has an iconic circle, it is the Moscow Metro, and in the 1970s designers created some designs that might be considered to be perfect diagrams. Just a perfect circle, and perfectly straight lines. The result is dramatically different compared with the more well-known London designs. Note that these straight lines are not at regular angles in any way, the designer chose whatever was necessary in order to straighten them. These maps are probably the most successful official versions to deviate from what is increasingly held to be the 'correct' way to design a schematic map.
First multiple concentric circles map, designed by Erik Spiekermann in 1989
For all previous maps, note that there is just one circle. The concept of concentric ones has not yet been investigated. The first map with multiple concentric circles and perfect spokes seems to have been designed by Erik Spiekermann, a radical design to mark the reunification of Berlin. I only became aware of this map recently, long after I designed my own Berlin map (see below). This map seems to have been discussed in a magazine article, possibly 'Print Magazine'. Do you have more details of this?
Fare zone map from Karlsruhe, 2002
Not a map for navigation, but a good example of where the structure of information has determined the shape of the design. Here, fare zones are in concentric circles, and therefore the lines have been shown in concentric circles and spokes to match. Maps for journey planning for this city were in a more conventional style.
Paris Metro map from art/shop/eat London 2004
Sometimes I see map and it makes me stop and think. This one did, going into the category of 'file for future reference'. This is the first map that I personally saw that explored the concept of concentric shapes, albeit ovals. As usual, it is the straight lines that are weakening the design, failing to match the orderliness of the curves. In my own experiments, concentric oval maps are far harder to make orderly, although in the case of Paris, these shapes fit the structure of the city better.
Amsterdam tram map, first designed in 2007 by Eric Hammink
Another concentric circles and spokes map that I only recently discovered, and one that works particularly well because of the compatibility between the design rules and the structure of the network.
Leipzig tram map, 2012. A conventional design with circles at the centre
A conventional map of Leipzig's tram network, with a circular centre. Would the design be stronger if the entire map was executed in this way? Circles seem to be an idea that currently interests many designers.
Concentric circles map of London by Jonathan Fisher, 2012
This is the map that inspired me to put pen to paper. Here is the first concentric circles design I know, although not without its problems. London has a Circle Line (more of a 'paperclip' these days), but its shape is anything but circular, and it is far wider than tall. Any attempt to turn this into a geometric circle is going to really distort geography. Not only this, but with the British preference for horizontal lettering, there is going to be an almighty battle with the typography of the design. Don't ever try to make the Circle Line a perfect circle, it just doesn't work (or prove me wrong!). This design also highlights the problem with mixing circles and 'standard angles' straight lines. These have do not relate well to each other, reducing the coherence of a design. If you are a circle, you don't really care about those particular angles. There is nothing special about them, making the different elements of the map harder to integrate. The result on this design is that it feels a bit arbitrary whether a particular route is deemed 'orbital' and made circular, or made a straight line. Compare the Docklands Light Railway (light green) to Lewisham in southeast London with the adjacent Overground lines (orange).
My concentric circles map of the London Underground, 2013
Still, for a design to be inspirational, there must be something special about it, but I wanted to make the circles and straight lines communicate more effectively. The solution was to make all the straight lines spokes, intercepting every circle at 90 degrees. Unfortunately, I ended up cheating. Some straight lines are merely parallel to other true spokes, others are tangents to circles. This is something I may have to address at a later date, once the new Thameslink service in London has been sorted out so that the goalposts have been fixed.
My concentric circles map of the London Berlin S- and U-Bahn, 2013
Madrid also reguired some cheating with the straight lines, Berlin is the first map where every one of these is a true spoke. It took me a few attempts to find an appropriate centre for the network (choose well, and the map falls into place, choose badly and it may never be right). For Berlin, it was staring me in the face, the station Stadtmitte - of course! And, after realising that, the rest of the map was easy, and this is probably the least geographically distorted design of all.
My concentric circles map of the New York Subway, 2013
I had always assumed that a concentric circles map would only be effective for a city with a circle or loop line, empasising a logical feature present in the network. Without this, and with a grid structure in Manhattan, I never expected New York to be a success at all. This time the centre of the map was off the mainland, but again once this was found the map really designed itself. Perhaps this is the most powerful orderly design to date.
Where next? Seoul and Beijing have large challenging networks, and so would be good to attempt, and maybe these rules can be adapted to suit some cities better. Perhaps concentric ovals will work well in the right circumstances. Perhaps spirals. There is an infinite space of possibilities to explore, so don't expect fast progress!