Crossing gates should come down 20-30 seconds before the train gets there, pretty much regardless of train speed. I suppose that the difference may be that, at

Crossing gates should come down 20-30 seconds before the train gets there, pretty much regardless of train speed. I suppose that the difference may be that, at higher speeds, the train is further away when the gates come down, and people don't realize how soon it's going to get there, and so decide to go around the gates. (And, I suppose, when there is an accident, it's more likely to be fatal because of the speed.) If you meant anything other than those two options, though, I'm not sure why you think that "grade crossings are inherently unsafe at those speeds".