“Dodecalinear” is fancy designer-speak for a 30-degree grid: it refers to the fact that the route lines can be laid out in twelve directions instead of the eight allowed by a standard 45-degree or octolinear map.
To put it in simpler terms: imagine six lines that pass through a central point – from that point, you can now travel in any of twelve directions. Technically, you can use any combination of opposing angles and still have a dodecalinear structure, it’s just that the regular spacing of 30-degree angles usually creates the most visually appealing look.
That said, creating a competent dodecalinear transit map is easier said than done, and should really only be attempted when it can bring a tangible benefit to the map. I used this form of map to great effect in my own unofficial rail map for Portland, Oregon – here, the 30/60-degree angles allowed me to more accurately depict the street grid in the downtown area of the city.
This map, designed by Joan Zalacain as part of his Masters of Information Design at the renowned University of Reading, certainly uses the extra angles to good effect. Amsterdam’s radial canals almost beg for this type of approach, and it’s executed deftly. The final version at the bottom right of this panel, with all the details of the city added in, looks quite superb, even in this dimly-lit Instagram photo.
Source: nghtwrks/Instagram – link no longer active
