Frog is what they call, why I don't know? When I worked in a mine they called this thing a frog. They came in handy when a muck car full of dirt came off the track. You'd drag that derail over a frog and most the time the detail would jump back on the track, but not always. If that didn't work you'd get all the mine management coming in to work their ideas and barking orders, especially if you had a main haulage shut down. It was a big deal when no trains could go in and out.