With rear end collisions, there is always the possibility of the victims suffering from whiplash. That’s why head restraints are so important to your safety provided they function properly.
Although the primary purpose of a head restraint is to prevent injury to your neck during a rear end crash, there are significant differences in the way head restraints are made. Some are adjustable, while others remain in a fixed position. Some adjustable restraints can be locked into position, but others are not manufactured to lock. There are also variations in height as well as the distance from the back of a person’s head.
The Insurance Institute for Highway Safety recently conducted a study of the seat/head restraint combinations in 44 current model SUVs. Only six of the models tested received a passing rating for protection against whiplash injuries in rear end crashes.
According to the study, if a seat/head restraint is well designed, it should keep the head and torso moving together during a rear end collision. When a car is struck in the rear, the seats push the occupants’ torsos forward. If the occupants’ heads are not supported properly, they will remain behind as the torso moves forward. This difference in motion between the two body parts results in the neck being snapped back. The faster the torso moves, the more sudden the movement, and the greater the forces exerted on the neck, which makes the possibility of whiplash more likely.
A head restraint needs to extend at least as high as the center of gravity of the tallest occupant’s head. A restraint should be located close to the back of an occupant’s head so it can provide support at the point of impact.
The Institute evaluated the seat/head restraints with a two-part test. First, the restraint geometry was measured to determine its height and distance from the head of an average-size man. Seats/head restraint combinations that flunked the geometry test were immediately given a poor rating because they cannot provide protection for enough different body types in rear-end crashes. If the seat/head restraint combination was rated either good or acceptable for its geometry, it was then tested to see how it performed while in motion. The testers used a movable platform and a dummy to measure forces on the neck. This test, known as a sled test, simulates a collision in which a non-moving vehicle is struck in the rear end by a vehicle of the same weight traveling at 20 mph.
In general, the researchers found that four out of five SUV seat/head restraint combinations tested were marginal or poor in terms of whiplash protection. This was the first time the Insurance Institute for Highway Safety had tested SUV seats using a dummy to measure forces exerted on the neck during a rear-end crash.
The SUVs whose seat/head restraint combinations received an overall good rating were the Ford Freestyle, Honda Pilot, Jeep Grand Cherokee, Land Rover LR3, Subaru Forester, and Volvo XC90. SUVs with poor ratings included such popular models as the Chevrolet TrailBlazer, Ford Explorer, and Toyota 4Runner.