New legislation pushes for new tractor trailer guards

(CBS) -- This is what can happen when a car hits the side of tractor-trailer. With the vehicle traveling under the trailer, the force nearly rips the roof off.

It's called an underride crash and can also happen when a vehicle collides with the back corner. The Insurance Institute for Highway Safety believes about 250 Americans are killed every year in these type of crashes.

Marianne Karth lost her two daughters, Annaleah and Mary, in a crash four years ago. The family was hit from behind. Their car spun around and the back slammed under a tractor-trailer. The two girls in the backseat were killed... Marianne, who was in the front, survived.

"Their lives were just abruptly ended, they didn't set out that day knowing that their lives were going to be over," she says.

Marianne joined a group of lawmakers on Capitol Hill who plan to introduce new legislation to prevent these accidents. It would require big rigs to have guards on the side to stop a car from going under.It also calls for stronger and wider guards on the back.

Congressman Steve Cohen (D-TN) says that could save hundreds of lives every year.

"They should be mandated, it's not different then airbags or seatbelts," he says.

The added weight of new guards could force truckers to reduce their payloads, which could lead to more trucks on the road.The Truck Trailers Manufacturers Association told us they want to review the new legislation before commenting.

"I know that truck crashes can be survivable," Marianne says.

Marianne believes that if new guards were in place during her crash, her children would be alive today.