As I noted in the introduction to this blog I have been working since last spring to try to encourage some friendly interaction between strangers in a space that’s normally fairly fallow socially: a bus stop.

People in public spaces tend to politely avoid social contact with each other, other than brief phatic1 communication. In the case of people at a bus stop, you’ve frequently got a small clump of people standing in close proximity to each other, with ostensibly no place to be, since they are after all waiting for a bus. It’s a group that’s ripe for some sort of intervention.

I am certainly not the first person to think it would be interesting to “activate” a bus stop and encourage social contact where none had been before. I’ve found many delightful examples of clever installations in and around public transit spaces, and in fact many transit systems go so far as to provide funding for art pieces. My particular interest, though, is in not merely pleasing the transit patrons with some piece of interesting or beautiful art, but rather getting them to interact with each other in a fun, and hopefully rewarding way.

A machine

Towards this end, I am working on a second iteration of a machine to do just this. Its mechanism and theory of operation are the same as an Etch-a-Sketch, insofar as it’s got two control dials: one for up/down and the other for left/right. The difference in my version is that the dials have intentionally been separated so that one user can’t possibly reach both at the same time. This then necessitates a collaboration between two users if they’re to make a drawing that isn’t just a horizontal or vertical line.


Instead of doing everything using hand tools as I did last time, this time around I’ve been looking to hone some of my digital fabrication skills. There’s an open-source piece of two-dimensional drawing software I’ve been using called LibreCAD which is both and free-as-in-speech (“libre”) but also free-as-in-beer (“gratis”). And what’s better than combining free beer and speech? Not much.

The software has, as is par for the course in digital design land, a bit of a steep learning curve. I spent a lot of hours getting many things wrong before I got to a point where I was finally able to more consistently and effectively get things right.

I have gone through many (~10) revisions of the mechanical drawing for the bus stop installation. Here’s the version that’s current as of this writing:

bus stop machine cut plan

The big things sticking out to the right and left are the knob controls for the two users. The left knob drives the X gantry, and the right knob drives the Y gantry. The different colors are different layers of the drawing, which illustrate different subsystems. Here’s the original DXF file if you’re interested in seeing it more closely. I don’t know how universal the DXF format is, so if you want to preserve the layer names, etc., you may need to use LibreCAD to open this file.

  1. I was introduced to this term in Kio Stark’s book When Strangers Meet. Phatic communication is the formal linguistic term for language with only formal meaning, e.g. “hi, how are you?” when the speaker doesn’t actually mean to inquire how the other person is. Wikipedia page on phatic communication.