The only studies done have been are head-on collisions. Most school bus injuries are from roll overs as school buses are very top heavy.
Also...School bus injuries and deaths are compared to **all** travel in cars regardless of who is doing the driving and when. No studies have been done comparing the school bus with the parents driving the child to and from school with the child secured in a seat belt.
There are approximately 60,000/year admissions to the emergency room for school bus injuries. Nearly all could be prevented with seat belts and having an adult ( other than the driver) supervision in the back of the bus.
The saddest school bus injuries are when the book bag straps or clothing of a child is caught in the doors of the school buses and the child is dragged ( usually to their death.)
Finally,....School bus design is STUPID. There are rarely escape doors in the roof on the buses and this complicates rescue when the bus rolls over.
How safe are school buses compared to all other motor vehicles? School buses are one of the safest forms of transportation in the United States. More than 42,000 people are killed in traffic crashes on U.S. roads every year. Every year, approximately 450,000 public school buses travel about 4.3 billion miles to transport 23.5 million children to and from school and school-related activities. Yet, on average, every year, six school age children (throughout the U.S.) die in school bus crashes as passengers. NHTSA strives to ensure that there are no fatalities in school buses.