VIEWPOINT: ADVANCES IN REAR-SEAT SAFETY

Today’s cars are fitted with as many as 10 airbags, and seatbelts that can be designed to automatically tighten before a crash. Much of this technology—and the government safety standards that dictate them—has focused on front-seat occupants. Applying similar technologies to rear seats is complex because of differences in seating position and packaging for the safety systems themselves. 

But that has not deterred ZF TRW from pursuing next-generation safety systems engineered specifically to help better protect rear-seat occupants in a crash. Steve Peterson, director of North America occupant safety systems engineering, explains the unique challenges and intriguing results of ZF TRW’s work to date on enhanced safety systems for rear-seat passengers.

Why is there a discrepancy between front and rear seat safety systems?

The short answer is that occupancy rates for rear seats in the U.S. are only about 10%. Of course the driver’s seat is 100% occupied, and in most cases the only other rider is in the front passenger seat, so those positions have received the most attention.

So why is rear-seat safety important?

The largest population riding in the rear seat is children. And while this is still the safest place for them to ride, we work to design improvements for the rear seating environment to help further protect them. Most injuries to children in rear seat crashes are head injuries, in which they strike hard objects within the rear vehicle interior. So softening the surfaces in the rear seat environment could be helpful. 

Elderly people make up another significant population of rear seat occupants. Their primary injuries in crashes are to the chest and torso. This is where load-limiting seatbelt technologies and perhaps rear seat airbags could help mitigate such injuries.

Are there quick steps that could improve rear-seat safety?

There are several. We support the use of a seatbelt reminder system for the rear-seat occupants. Studies show that seatbelt usage by rear-seat occupants is more than 10% lower than for occupants in the front seating row, where a reminder light and chime are present. 

We also recommend that rear-seat belt system include the seatbelt pretensioning and load-limiting technologies used in the front row to improve the effectiveness of rear seatbelts.

What’s next in rear-seat safety?

Government agencies are now paying greater attention to this issue. For example, Europe’s New European Driving Cycle introduced a new ratings scheme in 2015 that demands systems perform for a wider range of occupant sizes to earn a top five-star rating. 

In the U.S., the National Highway Traffic Safety Administration is looking at advances in rear-seat safety that could eventually lead to new safety standards. ZF TRW worked closely with NHTSA and the University of Michigan Transportation Research Institute in Ann Arbor on a study of rear-seat safety that included seatbelt technologies and the potential use of rear seat frontal airbags that can deploy from the roof or the rear of the front seat.

Are rear-seat airbags the same as systems used in the front seat?

The concept is the same. But the execution is very different. In the front seats, you have a steering wheel or dashboard in which to mount airbags, and there is a relatively narrow range of distances between those mounting points and the person sitting in front of them. It’s a different situation in the rear seat. 

To deploy an airbag in front of an occupant in a rear seat, you need to account for the fact that the seat directly in front of the occupant could be moved forward, slid back or reclined. If the airbag is mounted in the ceiling (bag-in-roof), it has to deploy properly regardless of where the front seatback is positioned. Likewise, if the bag is mounted in the back of the front seat (scarab bag), it has to adapt to both the angle of the front seatback and the distance between the seatback and rear occupant. ZF TRW has developed prototypes of both airbag configurations.

Click HERE to learn more about ZF TRW safety systems.