Google's transit predictions, which use aggregated and anonymized Location History data, have been available since last year. But while Maps previously just told users how busy they could expect a train to be at certain times, now it tells them how busy the train is right now.
Maps is also adding a similar feature for when you're ordering food through the app, with expected wait and delivery times as well as live order status.
With cases rising alarmingly fast in the U.S. as well as the UK, public transport is a necessity for many, like the essential workers keeping people alive, fed, and safe. So to keep yourself and others healthy, wear your mask, stay as far from others as possible, and when possible, wait for a less crowded train or bus.