This software polls the CTA Bus Tracker API once per minute in order to collect "stop events," each one representing a bus passing (or stopping at) a bus stop at a particular time. Each stop event is associated with a geocoded location. Stop events are stored in a PostgreSQL database. The resulting data is suitable for analyzing or mapping bus frequency by geographic boundary, time, date, etc.
You'll need PostgreSQL and the PostGIS extension installed. Create a database and load cta.ddl to set up the schema.
You will need SBCL to run chicago-transit, along with the Quicklisp library manager.
Copy the file config.lisp.example to config.lisp and set the *bus-api-key* (you can obtain a key at http://www.transitchicago.com/developers/bustracker.aspx) and *database-connection-spec* parameters.
Run ./build.sh in the top-level directory. The first time you do this, Quicklisp will download and install all of the Lisp dependencies.
Run the chicago-transit binary in the same directory as your config.lisp. This will open a REPL where you can interact with the application, as well as a Swank listener on the default port (4005) so that you can connect to it from Slime in Emacs.
Every time you start the application, it will immediately update its local list of CTA routes and stops. It will then update that list every night at midnight, and retrieve predictions (and generate stop events) for every bus every minute on the minute.
All logging is done to the syslog facility using the identifier bus-api. On older systems, you'll want to look in /var/log/syslog or /var/log/messages or something like that. To watch the logs on a modern system using systemd, run journalctl -f SYSLOG_IDENTIFIER=bus-api.
(cta.controller:start) at the REPL starts the polling loops (but this should not be necessary unless you have manually stopped them). (cta.controller:stop) suspends them. (cta.controller:debugging-on) and (cta.controller:debugging-off) enable and disable a debugging mode where the URL of every HTTP request made to the bus tracker API is logged to syslog.