BGR Media reports that Google Maps is popping up alerts, asking for information on how crowded the train/subway is:
https://bgr.com/2019/04/17/google-maps-features-how-crowded-is-your-train-question-explained/ .
This is just the start of beefing up Maps’ ability to predict traffic levels – I expect Google will be collecting much more information about public transportation, and use that data to power its AI. In the future I could see Google Home offering route planning comparisons between an Uber or train: including informed predictions about how long each will take, how crowded the train will be, etc.