Interesting discussion.

Though it's been quite a few years, I've seen small self-propelled cranes
(not truck-mounted hi-rail cranes) pulling or pushing a few flatcars with
work supplies.

I assume the operators of these cranes, where they still exist, do not
need to be qualified engineers and movements are made under MoW rules. I
do not remember whether these cranes had compressors for air brakes on the
flatcars. I would presume that they do.


Another interesting note is that while large rail-only cranes have basically
disappeared in North America, they can still be found in Europe and new
cranes of this type can still be purchased by railroads. Many of these
cranes have hydraulically-extendable booms specifically designed wor work
under catenary.

-- Ernest