I originally posted this map on Twitter, but I’m also putting it on the blog for posterity, as well as to fully detail the design decisions that went into it.

I’ve long thought that there’s been a design opportunity with Denver rail maps for a large circular arc for the light rail stations running south around the edge of the downtown area out of Union Station. I’ve doodled with ideas over the years, but I’ve never found them particularly satisfying or aesthetically pleasing. There was always a disconnect between the curved sections and the regular orthogonal lines which stopped the map acting as a cohesive whole. Until finally, I thought: what if I did away with straight lines all together?

It was certainly a concept well outside my comfort zone, as I’m very much used to working with straight lines and 45-degree angles. The relationship between elements is fairly easy for me to define when working within these “regular” design rules, but curved lines are another whole world to me! I had to draw an intentionally loose working diagram with a Sharpie before I even started work on the computer to convince myself that this could even be done. The fat tip of the Sharpie prevented me from getting overly concerned with detail, allowing me to concentrate on the general form and flow of the map. One thing it showed me was that such a diagram was still basically topologically correct: all the lines ended up in the pretty much the right place relative to each other. Encouraged, I began!

Even with the sketch, it look me a few different versions before I finally hit upon a workable solution to my problem: spirals! Concentric circles were almost there, but created an ugly “peanut” shape in the middle of the map (which you can see in the working sketch), where I really wanted a smooth curve from Union Station all the way around to Peoria. Some trial-and-error gave me the right spiral decay required to achieve this and still leave room for station labelling, and then I set up a set of nested spirals for all the lines out of Union Station to act as master curves. From there, it was really just a matter of cutting the spirals at the right points and rotating/reflecting them to join back together correctly. In a way, I basically “unrolled” the spirals to go where I needed them to – along with a couple of shorter connecting curves where the lines change direction sharply (see the “G” and “W” lines). Spacing stations evenly along the curves provided a new challenge, but I was able to work out a system that gave pleasing results: there’s a lot more eyeballing and manual adjustment of labels to get things looking optically “right” than there is with standard 45-degree maps!

The downtown loop was probably the most challenging part of the map, and I almost chickened out and made those lines straight. However, I persevered and came up with a solution that allowed me to keep everything curvy while still staying somewhat true to the real-world alignment of things. I’m especially pleased with the way that the “L” line swoops gracefully up to join the “A” line at 38th & Blake: it made this troublesome part worth the effort!

While I’m extremely happy with the finished product, there are still a few things that I can improve – not the least of which is learning to manipulate Bezier curves so that the end result looks more organic and a little less mathematical. It’s a real skill, and I’m not quite there yet. Some have commented that the map is incomplete without the downtown/mall shuttle buses and the Flatiron Flyer bus services to Boulder, and these concerns are completely valid. I’m not sure I’ll ever address them, as I feel I’ve done what I wanted to with this proof-of-concept map, but I hear you!

However, the map has generally been received quite well, which is pretty darn gratifying when you take a left-field design approach. Some comments from Twitter are featured below: let me know what you think in the comments!