TransitFlow

About

TransitFlow is an experimental set of tools to generate animated transit maps and vehicle counts based on scheduled frequency.

TransitFlow consists of two parts:

1. A python script to retrieve and wrangle transit schedule data from Transitland, an open data service sponsored by Mapzen that aggregates public transportation data from around the world. Transitland enables us to merge transit schedules from different operators without having to interact directly with each operator’s GTFS data.
2. A template to generate a Processing sketch to animate that data.

Let’s look at a few examples of what you can do with TransitFlow.

Examples

Bay Area

python transitflow.py --name=bay_area --bbox=-123.280334,37.011326,-120.607910,38.955137 --clip_to_bbox

San Francisco

python transitflow.py --name=san_francisco --bbox=-122.515411,37.710714,-122.349243,37.853983 --clip_to_bbox

Chicago

python transitflow.py --name=chicago --bbox=-87.992249,41.605175,-87.302856,42.126747 --clip_to_bbox

Mexico City

python transitflow.py --name=mexico_city --bbox=-100.041504,18.453557,-97.701416,20.040450 --clip_to_bbox --date=2016-06-01 Many more examples available here.

How it Works

Getting the Data

TransitFlow makes use of three Transitland API endpoints to get the data:

1. Stops to get transit stop locations
2. Routes to get operator vehicle types
3. ScheduleStopPairs to get origin -> destination schedule stop pairs

The ScheduleStopPairs endpoint does the bulk of the work. Each ScheduleStopPair is an edge between an origin stop and a destination stop. Each ScheduleStopPair includes origin departure time and location, destination arrival time and location, and a service calendar which tells you which days a trip is possible. TransitFlow searches for all ScheduleStopPairs for a specified operator or for many operators within a specified bounding box. It then parses the data, calculates trip durations and bearings, and concatenates everything into a tidy, tabular dataset. It then outputs this dataset to single CSV file, which will drive the animation.

Visualizing the Data

TransitFlow generates a Processing sketch file based on your command line arguments. The Processing sketch reads in the CSV file from the previous step, uses the Unfolding Maps library to load map tiles and convert geolocations into screen positions, and animates vehicle movements from origin stop to destination stop using linear interpolation. Note, that we are animating between stops and not yet following the exact route line.

How to Use It

First, navigate to the github repository and follow the relatively painless set-up instructions.

You can visualize a single transit operator by passing in the operator’s Onestop ID as a command line argument.

What’s a Onestop ID, you ask? As part of Transitland’s Onestop ID Scheme, every transit operator, route, feed and stop are assigned a unique identifier called a Onestop ID. You may look up an operator’s Onestop ID using the Transitland Feed Registry.

For example, the onestop ID for San Francisco BART is o-9q9-bart. To visualize BART’s schedule on today’s date:

python transitflow.py --name=bart --operator=o-9q9-bart

You can also visualize many operators within a region by passing in your bounding box of interest as a command line argument. I like using bboxfinder to draw a bounding box. The bounding box must be in the format: West, South, East, North. For example, to visualize Portland transit flows on today’s date:

python transitflow.py --name=portland --bbox=-123.035889,45.257489,-122.250366,45.798170 --clip_to_bbox

To view your transit visualization, navigate to sketches\{name}\{date}\sketch and open the sketch.pde file. This should open the Processing application. Simply click the play button or command + r to run the animation.

Command line arguments

Key	Status	Description	Example
--name	required	The name of your project	--name==Boston
--date	optional	Defaults to today's date	--date=2017-08-25
--operator	optional	Operator onestop_id	--operator=o-drt-mbta
--bbox	optional	West, South, East, North	--bbox=-71.4811,42.1135,-70.6709,42.6157
--clip_to_bbox	optional	Clip results to bounding box	--clip_to_bbox
--exclude	optional	Operators to be excluded	--exclude=o-9-amtrak
--apikey	optional	Mapzen API key	--apikey=mapzen-abc1234