Author here. I self-published this book as a sequel to my previous book, The Definitive Guide to GTFS.

The first one is all about public transit schedules in GTFS format (used by Google, Apple and most public transit apps).

This one is about real-time data that complements the scheduled data (data such as vehicle positions, trip cancellations, etc...)

If you have any questions about transit, GTFS, or self-publishing, I'll be here all day!