All of the above can contribute to an accident. But the thing about speed is that it increases the severity of an accident, and the injuries. My son was in an intersection accident. he was broadsided by a speeding driver in a 4x4 pick up truck. He suffered traumatic brain injuries because his brain went from 0 to 45 miles per hour in less than 1/100 of a second. the car he was a passenger in was pushed over 100' past the point of impact. My son will never be the same, and he requires 24 hr care. If the other driver had been doing the speed limit she could have slowed her truck enough that my son would have suffered no injuries, or she could have avoided the accident all together. Her speed caused his injuries.