Like HowStuffWorks on Facebook!

How Whiplash-injury-lessening Seats Work


Whiplash-Injury-Lessening Seat Design
As the technology spreads, whiplash may no longer be the most common of all driving injuries.
As the technology spreads, whiplash may no longer be the most common of all driving injuries.
Andrew Bret Wallis/Digital Vision/Getty Images

Seat belts and harnesses really don't do much to protect your neck, at least not from the relatively small motions that are responsible for whiplash. Sure, when the harness snaps into place during a collision it can stop your torso from moving forward more than a few inches, but in the meantime your spine is busily coiling and uncoiling itself like a nervous snake. So what's a poor carmaker to do? Well, Toyota has come up with what they call a Whiplash Injury Lessening (WIL) Concept Seat. The cause of whiplash is the differential motion of your torso and head during the collision, so the principle behind a WIL seat is to keep these two parts of your body moving (or not moving) at exactly the same speed during the forward snap caused by a rear-end collision. But short of strapping the driver down with duct tape to prevent any forward movement at all, how exactly can they do this?

There are two parts to the WIL system. The first is in the back of the seat, which cushions the part of your spine that runs through your torso. This part of the seat is deliberately designed to compress during the forward motion of the collision, to minimize the pressure that pushes your torso forward. The second part of the system is in the headrest. As the lower part of the seat pushes against your torso, it also sends a signal to the headrest telling it slant upward at a diagonal angle (which is the position your neck is in when the s-shape occurs), then it pushes your head forward at exactly the same rate the back of the seat is pushing your torso forward. Result: Your spine maintains its normal shape during the collision and doesn't get bent. Ligaments aren't strained. Whiplash symptoms are less likely to occur.

At least that's the theory. The WIL seats are just starting to appear on models like the 2012 Camry and Lexus CT. The evidence so far is that, while whiplash may not completely be abolished by this new technology (something that still may not happen until self-driving cars come along), the severity of the injuries are now a lot less than they were before this technology arrived. And as the technology spreads to other models and manufacturers, whiplash may no longer be the most common of all driving injuries. It may be not even be very common at all.


More to Explore