Should school buses have seat belts for children?

HOUSTON (KTRK) -- Five years ago, Texas school districts were told to include seat belts on new buses they purchased. It had been a debate for years, and it often came down to the financial costs associated with the restraint devices.

The deaths of two students in a bus accident in North Texas convinced the legislature to enact the requirement. It did not require older buses to be retrofitted with seat belts.

The bus involved in Tuesday's horrific accident was purchased in 2008; however, the district said it did have lap seat belts. They could be seen in the wreckage of the bus Tuesday morning on the South Loop feeder.

PHOTOS: Deadly school bus crash in southeast Houston

Seat belts are always recommended, but according to a skilled accident investigator, they are no guarantee against serious injury or even death.

Robert Swint is CEO of ATA associates. The firm has been involved in a number of high-profile accident investigations. It applies forensic engineering analysis and 3-D technology to determine what went wrong in crashes, collisions and malfunctions.

"You have different forces affecting a body in accidents," he said. "From the front, from behind, and then from the side."

It's the lateral impacts that often cause the most serious injuries.

He cannot say whether the seat belts saved the two surviving students, and the driver. It could be where they were in relation to the impact of a 20,000-30,000 pound bus hit nose-first onto the pavement, after falling some 15 feet from the overpass. It could be where they were when the bus then fell onto its side.

"It's a very serious event, and you really can't design for that," he said.

Swint says the most advanced seat belts are those used in professional racing, like the Indy500, which cost thousands of dollars.