I didn’t realize that trackmobiles have been around for many decades. I was leafing thru my magazine The Military Engineer (I’m associate editor) and found some ads depicting them in the early 1950s. Only then, they were called switchmobiles. They had large rubber tires and train wheels and could be switched back and forth in minutes.
Also advertised were some non-flanged wheeled bulldozers that were shown shoving freight cars around. I’m sure these latter vehicles damaged some of the cars. Interestingly, a few weeks ago I observed a back hoe pushing a NS boxcar into place at the Robinson Terminal in Alexandria, Va where I work.