If the crossing watchman is protecting the crossing and in communication with the train, then the train crew wouldn't have to stop and flag the crossing themselves.

Sorry, I'm straying a bit from the original post.

On our railroad, a crossing watchman communicates actively with highway traffic using his Stop Sign, flag, and lantern. However, except in case of emergency, he only communicates passively with the train crew, that is, they can see him performing his duties. A flag man does signal the train to proceed over the crossing.

Do you require flagging when pushing over a crossing protected by a Crossing Watchman who does not signal trains to proceed?

I'm definitely not professing to have all the answers and more seem to crop up as I go along, but here I go:

A crossing watchman is considered an "active warning device," but according to the law, the person protecting the shove must be in communication with the train. It would be very easy for the crossing watchman to give a hand signal to the train crew to let them the crossing is protected and it is clear to proceed. And once they're in communication, they fall under Hours of Service.

Now since the law concerning shove moves specifically states that you can only shove through a grade crossing equipped with flashing lights and gates, then the crossing watchman would effectively have to become a flagger for a minute or two until the train is clear in order for a train to shove through without stopping.

As to your question (and in my opinion how the laws are worded), if the crossing watchman is not in communication with the train, then the train crew would have to flag the crossing. I know that sounds stupid, but I'm pretty sure I'm correct on this one. I emailed our FRA guy with some questions and he's been very helpful, so I might suggest you do the same just to be sure. So many laws all tied together and it can get confusing!!!

At our museum, we don't have a crossing watchman, but we do have a watchman's shanty! Maybe I can recruit somebody to do that job...