was there a curve nearby so that the train could not be seen until it was right on them?? it seems like it took so many by surprise. I just don't understand that unless there was limited view of the tracks
I don't think so. Looking at the photos appears to be pretty straight. I think the sirens in the parade might have prevented the driver from paying attention to the sounds made by the train. Also, it appears to me the first truck passed, but didn't leave room for the second truck to pass all the way through.
Presumably the second truck should have waited until he had room to go all the way through.