How safe is a school bus without seat belts when it comes to protecting children in the event of a crash?
NBC News investigative and consumer correspondent Vicky Nguyen traveled to a commercial crash test facility to see what can happen when an accident occurs in a bus without seat belts, which aren't required under federal law.
Three people were injured after a school bus fell onto its side in a crash in November in Arizona, and other incidents have occurred in Texas, North Carolina and Florida in the last year. Only eight states make it mandatory to have seat belts on large school buses, according to the National Conference of State Legislatures.
To observe the potential dangers of buses without seat belts, Nguyen went to a facility in Indiana called CAPE, where engineers rigged a bus with sensors and cameras to capture every angle inside the cabin.
The bus was filled with 15 dummies, eight wearing seat belts and seven without them, and then was driven off a ramp at 35 mph to simulate a rollover scenario. The seat belts used in the demonstration are manufactured by IMMI and cost about $7,000 to $10,000 per bus.
One unbelted passenger went flying across the aisle, snapping their neck on a seat, while two other unbelted passengers became human projectiles, slamming into another passenger. Meanwhile, all the passengers with seat belts remained in their seats.
Nguyen showed the footage to Sen. Tammy Duckworth (D-Ill.), who recently reintroduced the School Bus Safety Act, which would require three-point seat belts, data recorders and automatic braking for all school buses.
"Anybody that cares about children, if they saw this, they would just be horrified at the dangers that they are putting their children into,'' Duckworth told Nguyen.
The National Transportation Safety Board recommends that all new school buses be equipped with three-point seat belts, but the National Highway Traffic Safety Administration says the compartmented seats provide protection in a crash. The NHTSA declined a request by NBC News for an interview.
"Most people have not seen this kind of footage, and I think that if parents saw what was happening inside these school buses, they wouldn't put their kids in these buses without seat belts,'' Duckworth said.
-With Scott Stump