I have been thinking the same thing. I've got a railroad bridge over a major waterway near me. The RR bridge carries Amtrak, freight trains and (I think) a little commuter rail. The RR bridge opens often to allow tall marine traffic to pass through below. I would expect that the bridge openings and train crossings are all scheduled, and that the schedule would be made available somewhere. I've yet to find any resources listing regularly scheduled trains or bridge openings.I've looked for freight train tracking information and have found nothing in the US. Amtrak has live tracking for their passenger service.
It's odd that you can find very precise real-time tracking information for commercial airplanes and ships, but not for freight trains.
I suppose I could find the daily Amtrak schedule and extrapolate from the arrival/departure times, but as you say...so much other scheduled transportation info is so easily available online, it seems odd that rail schedules are so hard to find.