It's interesting that the sign is in English, though. I guess that Italians ignore them as a matter of principle, whereas there's at least a small chance that someone from the British Isles or North America might obey them.
Oh, the train in question was this one:
€20 for a 21km ride through the countryside — very agreeable. Mind you, the €8 ride to pick the train up at the start was less fun, especially when the driver ran into the back of the car in front then drove off after the other driver pulled over...