The first time I rode on one of these, my wife and I were on the way to Zermatt and the gps led us to a train station. We got to the ticket machine snd thought it was some kind of toll until we saw the train arrive and it all made sense. It’s honestly kind of terrifying at first, but also pretty cool. Not sure how I would feel driving into a train somewhere else though.
It's called the Furka car train. I think the price depends on when you book, but I think we paid 27 CHF on the spot. The train takes 15 minutes vs 45 minutes to drive the pass under good conditions. Sometimes the pass is closed and the train is the only realistic way. https://www.zermatt.ch/en/arrival/Arrival-by-car/Car-Train/Furka-Car-Train