School buses transport millions of children to school across the nation every day. They're billed as the safest way to travel the roads. But a growing number of experts are saying they're not safe enough.

There is a heated debate on the issue nationwide, and it's not all about safety. It has a lot to do with money, technology, and politics.

The big yellow school bus is an icon, a symbol of America's public education system. But like any vehicle, it doesn't always reach its destination safely.

Just a few weeks ago a school bus in Churchill County rolled, sending three students to the hospital. Although the injuries were just bumps and bruises, it could have been much worse. School bus rollovers have been caught on on-board security cameras, showing students tumbling through the seats and aisles.

In most cases, students weren't wearing seatbelts, because in most school districts around the country, as well as in Nevada, seatbelts on buses are not required.

"Front impact, the student would be sitting here," Washoe County School District Transportation Director Rick Martin explained, during a tour of a school bus' safety features. "They would go forward, then back," he said, describing the effects of a collision.

The current system is based around a concept called "compartmentalization."

It is the system of high, padded seat backs and closely spaced seats that is supposed to act like a sort of cocoon, shielding students from harm in a front- or rear-impact accident.

"If there is an impact, they're not moving," Martin said.

Compartmentalization is the method endorsed by the National Highway Traffic Safety Administration, the group responsible for making recommendations to Congress.

In 2002, the group testified to Congress that this system is "effective," and that seatbelts were unnecessary, citing the relatively small number of deaths of student passengers-- six per year on average.

But in 2006 another federal agency, the National Transportation Safety Board, came out in opposition, saying compartmentalization doesn't protect all passengers in all types of crashes.

One year later, the American Academy of Pediatrics came out in favor of seatbelts on buses.

That's a priority shared by many parent organizations around the nation.

"Compartmentalization doesn't work," National Coalition for School Bus Safety President Dr. Alan Ross said. "The simple way to avoid the child being thrown around like a missile is to apply a safety belt."

Still, seven years after the NTSB's recommendation, very few school districts have made the change.

One reason for that is cost.

"The only reason why we're not doing it is because of profit and politics," Ross said. "The school bus industry is a multi-billion dollar a year private industry that spends a lot on lobbying."

Retrofitting a fleet with seatbelts can cost up to $30,000 per bus. It's money most districts just don't have.

"Obviously in these economic times, it's not like we have a surplus of money to put into a lot of different things," Martin said.

Written by Arianna Bennett