Have been using MBTARailCommuterRail for years; it’s the best $1 I ever spent! So, so worth it - train tracking, alerts, and updates from fellow riders about everything. Passengers are able to post information/updates in realtime: track numbers, delays, breakdowns, track issues, and train configuration, which cars have heat or A/C, number of conductors, which doors are opened, and so forth - much more detailed info and provided earlier than the MBTA does. Users can favorite their lines & train numbers, app pinpoints on map where train is located (great when running for the train), and shows ETAs for stations along the line. Depending on the users, there are sometimes even funny debates - at Halloween for instance, whether candy corn is great or a product of the devil (spoiler alert - I happen to like it ) Highly recommend!