Both posts above are quite true, all employees watch trains by as their duties allow and they will notify the crew that they have watched the train by, in the days of cabooses, they would wave/signal the rear end crew, modern days its on the radio.
For example if I were by myself, at mp 20 watching the train with the ABC2345 by, I would tell the train, "ABC Husman at mp 20 to the AB2345, hiball the west side." or "... good inspection west side." If somebody was with me or I was with a gang, it might be ".... hiball both sides."
Dave H. Painted side goes up. My website : wnbranch.com
Further to NHTX's posting you hear this on scanner chatter where I railfan (a double track CP mainline that sees Amtrak service). All crews comment to a train they have met or passed over the radio, as do crews on the ground. We don't see the CP railroad police as often as we used to, but they too would invariably say something to any train that went by.
I have seen CN engineers get out of the cabs to inspect a passing train but usually that is in summer when they likely also want a breath of fresher and cooler air. I remember a particularly hot day where the entire crew was not only on the ground but one walked over to me and offered me a small bottle of chilled water! So I guess they were inspecting the railfans too.
Dave Nelson
To build on what Mr. Husman said about inspecting passing trains, many railroad rule books required ALL employees trackside, to inspect passing trains for defects such as overheated journals, sticking brakes, dragging equipment, low hanging air hoses, shifted loads and such. This included station agents, tower operators, signal maintainers and MOW personnel, as well as other train crews. In today's electronic world and, in the absence of many of these employees, the railroads now rely on machines, which aren't fool-proof either.
I would like to throw a little prototype technicolor on the process shown in the Trackside Photos of a passing train being inspected.
Normally the engineer does not get on the ground to inspect a passing train, he inspects it from the cab window. The fireman and head brakeman would be the ones on the ground inspecting the train. They would also get off on the field side (outside) of the siding and stand ahead of their engine clear of both the siding and the main track to roll the other train by. Generally standing between tracks when a train is going by at speed is considered a very dangerous thing to do.
Similarly the conductor and/or rear brakeman would be on the ground on the field side of the siding, behind the caboose.