One note concerning the controllers. I do seem to remember from reading past incident reports, that when a controller clears an aircraft to cross a runway, they have certain responsibilities, such as looking to confirm a runway is clear and possibly looking at the aircraft being cleared to cross to confirm its position for where it will cross. I do wonder how they do all this at busy times in complicated situations when the chatter is non-stop. In addition, the crossing clearance may have been given well before the aircraft reached Kilo taxiway making such a task more difficult in a busy environment.