The BusGraphs Project

Whenever I talk about the way that I measure transit access, I run into a problem. The numbers are horrendous. Their magnitudes don’t line up with human-scale quantities. Consider some examples from the analysis in the last post. The number of possible journeys is in the low trillions. The total composite score works out to be a hair over 20 sextillion, a number that sounds fake. It doesn’t get better when expressing access as a ratio between the number of completed and possible journeys. Sectors around the Madison Park terminal of route 11—a reasonably frequent route—have ratios with three zeroes to the right of the decimal point. The purpose of the last two access analyses has been to evaluate whether the transit service of a sector is exceptionally good relative to the entire region. Numbers like these lack the innate sense of scale to communicate that assessment clearly.

As I was running the access analysis supporting Of Buses and Ballot Boxes, I encountered something that fascinated me. It wasn’t relevant to the piece itself, so I didn’t emphasize it there, but I knew it had to be the next thing I investigated.

I needed a way to test my suspicion that the ballot box designated by King County Elections as serving downtown was far less transit-accessible than other points in the downtown core. My analysis would divide Seattle into a grid of 80 meter by 80 meter sectors, and score them using a transit access measurement. Sorting the sectors by their score would allow me to compare the one containing that ballot box to others in downtown Seattle, which I knew, for sure, would dominate the top of the list.

I’m a last-minute voter, so I avail myself of King County’s ballot drop boxes. In the waning days of an election cycle, a ballot dropped in a mailbox might not get postmarked in time to count. Last election day, I was looking for a drop box near my place of work in downtown Seattle. I was surprised to find none in what I would consider the core of downtown. The walk down to South King Street and 2nd Avenue South wasn’t onerous, but it left me with a question.

In 2015, I became fascinated by King County Metro’s efforts to restructure its bus network in anticipation of the opening of two new Link Light Rail stops. At the same time, I found out about isochrone maps and the larger idea of access in transit. While I was creating software to measure the latter, the former served as a motivator and test case. I hoped that I’d be able to evaluate Metro’s proposed alternatives, come up with some on my own, and present objective measurements of which was best. As Metro’s plans proceeded through a series of revisions, I followed along through the outreach materials that they produced. The process never felt very scientific, and that frustrated me, but I dreamed of a day where tools like the one I was building would make that so.

“What if we planned public transit with the goal of freedom?” asks public transportation consultant Jarrett Walker in a blog post from this March. A little over five years ago, a presentation that he gave planted this question in my mind. Having a background in software, and unaware of anyone else who was thinking about this question¹, I started creating the tools that I would need to measure the freedom conferred by public transit systems. Within a year, I had sold my car and quit my job to focus full time on transit. I envisioned myself as establishing my own consultancy that would guide transit agencies through network redesigns using my software for generating measurements of transit network quality.