Thesis successfully defended!

And here it is.

I’m pretty proud to say that beside searching for the elusive schedule padding, and possibly finding some, I managed fit in a comment about the inevitability of death, a quote from Jerry Seinfeld, and a self-deprecating jab at the idea of human rights.

Also, I put videos in a PDF1. Who the hell knew that was possible?

Show 1 footnote

  1. but I’ve taken the liberty of sparing you from that in the version I’ve uploaded here.
Comments: 2
Posted in: Analysis | Method | Priorities | Technology Choices
Tags: | | | |

GIF of the day

Just another way of looking at speed distributions. This shows the distribution of observed speeds across several thousand route segments by percentile of the speeds on each segment. The animation changes as we’re shown different parts of the speed distribution on each segment.

relative speed distributions on route segmentsNot totally sure if it’s useful yet, but it is kind of pretty.

Comments: Leave one?
Posted in: Data
Tags: | | | |

Average vs Scheduled Speeds

Some news from the thesis front:

I think I’ve finally perfected my method for linking real-time data with scheduled stops. This is a comparison of the average (weekly) scheduled speeds to the observed average speed for each stop->stop segment. Results that look roughly as expected are what we all hope for.

TTC - differences in observed and scheduled speeds

Note that each classification is broken into eight equal sized quantiles

There is a lot of information in that little gif! More than I can explain here. More to come…

Higher resolution here by the way. It’s interesting to look at even if you don’t know Toronto. Also, the line widths are determined by the number of trips scheduled for each segment.

Comments: Leave one?
Posted in: Data | Maps | Method
Tags: | | | | |

Coloring Transit GPS Tracks by Azimuth

I’ve been spending today getting pretty seriously turned on by more than 400,000 transit GPS tracks colored according to their azimuth (measured from start and end points). Beside being pretty, it ends up being a stupendously good way to differentiate tracks which otherwise run quite close together.

Would anyone be interested in prints if I were to make some?

Comments: 7
Posted in: Design | Maps
Tags: | | | |

Making tracks

Here are some early results from my efforts to track transit vehicles, these ones in Toronto:


It looks like a crude system map, and it is, but it’s actually made of thousands of vehicle GPS tracks.

The vehicle tracks are oddly pretty; I keep wasting time just zooming in on different spots as new tracks are added. Here’s a transfer point at one of the subway stations:

transit station

Bus stops shown as ~20m circles

And what looks like perhaps a train station or a bus garage, below. This image also shows the relative frequency of service on different streets, something that becomes quite visible in the data when the lines are given a high degree of transparency.

bus garage?

Buildings for scale

And here’s an expressway carrying some limited-stop services:

expresswayAs of now, after just a week of  erratic development and testing, I’ve collected ~60,000 unique tracks, representing ~160 scheduled lines, derived from 3,200,000+ vehicle location records. About 50 new vehicle locations come in each second that I have my little script running.

Here’s what I’m doing so far, described algorithmically here, and implemented in a Python script:

A track is a set of ordered points, each point with a position and a time. The next step is to line the tracks up with the stop segments to which they’re scheduled, and if they’re actually close and the direction matches, to calculate stop times and segment durations from the observations. That’s actually turning out to be pretty difficult, but I’m sure I’ll crack it fairly soon. One thing I’ll have to seriously consider as I’m doing this is error in the location reports.

downtown signal degredationAs the first image and the one immediately above show, there is significant error in the data, particularly downtown where tall buildings are presumably interfering with GPS signal reception.

Comments: 2
Posted in: Data
Tags: |

Thesis Topics! (potential)

I’m being urged to get my act together regarding my masters thesis. I have a set of datasets I know I want to explore but I need to find a question of sorts that I can quite thoroughly answer with them. I also need to decide what type of person would be good to oversee this project — the ‘committee’ and whatnot. As I so often do, I’ll use you anonymous readers as the spur to set my thoughts to bytes and thereby make rigorous my abstractions.

SO: My dataset is real-time transit data feeds. I don’t care what buses are doing right now unless I’m waiting for them — I care what patterns they’re scratching into our lives. I’ve already demonstrated a Python script that will make random requests from a real-time API and store the results. There exist comparable API’s from other agencies that this script can easily be adapted to. As many agencies as have APIs I could squirrel data from.  That’s the dataset or set thereof.

My question has been more difficult to discover. I have so many! Here are a few:

I suppose  the first question is probably my best shot. Though #5 is certainly intriguing.  Now on to the lit review I suppose? *deep breath*

And then the committee! Beside my adviser, who is a regular transit user and quantitative geographer, I want another statistician/data-person, and this shouldn’t be too hard to find. I also want someone really good at graphic communication. For that latter, I want someone from DAAP. But I want to be sure that they don’t think or feel or act as though I’ve invited them to proof my presentation while others address it’s content; content is inseparable from presentation. Form does not follow function; rather both form and function must mirror each other. If I fail to make that happen, I will have miscommunicated or misunderstood my project.

Oh dear readers, what would you want to know if you knew, as I may, where all the buses are all the time?

Comments: 2
Posted in: Analysis | Psychological
Tags: | | | |