IN A CAR, a seat belt is often the sole factor in whether someone lives or dies in a crash.

Airplanes have them and even amusement rides have them. When it comes to passenger trains, like Amtrak Train 188, which derailed in Frankford on Tuesday night, seat belts are uncommon and often studies have not recommended them, though some wonder whether it's time to look again.

"I've wondered when I boarded the trains about the idea of seat belts. I think it's something the department of transportation, the NTSB, should look at," former U.S. Secretary of Transportation Ray LaHood told CNBC on Wednesday.

The Daily News reached out to the National Transportation Safety Board yesterday and a spokesman referred seat-belt questions to the Federal Railroad Administration. An FRA spokesman said decades of research and oversight has meant passenger rail cars are "engineered with various passive restraint interior design features" that allows passengers to "ride-out an accident in a contained space."

"Given their size and mass, passenger trains are able to absorb collision energy better than automobiles and commercial aircraft," the spokesman said.

Robert Paaswell, director of the University Transportation Research Center at the City College of New York, in a guest column in the New York Daily News yesterday, said seat belts "probably would not have saved the victims." He said they can't be compared to airplanes or cars.

"They are much bigger, and when they crash, seat belts that might keep a rider in place could actually injure the person from the sheer force of impact," Paaswell wrote. "Also, seat belts could hinder passengers from escaping a train that has crashed."

On Twitter: @JasonNark