The head of the National Highway Traffic Safety Administration on Thursday re-emphasized the agency’s call for seat belts on school buses in the aftermath of a crash in Chattanooga that killed six students.

Administrator Mark Rosekind said at a transportation safety conference in Washington that while school buses remain the safest way for children to get to and from school, they “can be safer.”

“And as the recent tragic crash in Chattanooga reminds us, there is no more heartrending, dreadful, tragic crash than when children are involved,” he said.

An average of five school-age children a year have died on school buses between 2006 and 2016, according to data compiled by the agency.

Until recently, federal regulators did not push the idea of requiring safety restraints. That changed in November 2015 when Rosekind called for a three-point seat belt on every bus.

Administrators in school districts where the over-the-shoulder belts have been introduced have noticed that they also help keep students in their seats and reduce disciplinary problems and distractions for drivers, said Derek Graham, director of pupil transportation in North Carolina.

Robert Molloy of the National Transportation Safety Board said he welcomes what he called “secondary benefits” of having seat belts in school buses. “But the reality is that it does save lives,” he said.

An NTSB investigation into a 2014 school bus wreck in Anaheim, California, found that one child “was in fact saved in that crash” by wearing a seat belt, Molloy said. By contrast, the agency found that school bus crashes in Chesterfield, New Jersey, and Port St. Lucie, Florida, resulted in fatalities that could have been prevented by the use of seat belts.

Molloy said that efforts to introduce seat belts on school buses are hampered by what he called “a lot of myths,” including that disoriented children might be trapped if the bus crashes or if a fire breaks out.

“I’ve never seen that, I’ve never heard that actually happening,” he said.

Only six states require seat belts on large buses. Many others, including Tennessee, have considered but dropped such legislation in recent years out of concerns including cost.

Federal agencies have estimated the price of lap and shoulder belts at $7,000 to $10,000 per bus. But Dan Daniels, an executive with school bus seat maker HSM Solutions, said at the conference that the price will come down as more school districts adopt three-point seat belts.

“As we get more participation, everybody’s going to benefit,” he said.

In the Chattanooga crash, police say the driver was speeding along a narrow, winding road with 37 elementary school students aboard when he wrapped the bus around a tree. The NTSB has not yet determined whether seat belts would have saved lives or reduced injuries on the bus.

(AP)