Truck & trailer don't appear to be totaled... Might have some dents and such but should be OK. Glad it wasn't worse and that dad is OK. The other driver who caused it, may not have even realized what he'd done if your dad din't contact his vehicle in any way. Pretty obvious that person wasn't really paying attention to begin with. So they could cause the wreck, and just continue on not even knowing. Still sucks of course, for you and your dad.