"It's disappointing that so many minivan seats are rated poor for rear impact protection," Lund says. "Drivers of minivans spend a lot of time on urban and suburban roads where rear-end collisions are common in stop-and-go traffic. Moms often are behind the wheel, and women are more vulnerable to whiplash injuries so they especially need good seats and head restraints."
Neck injuries are the most common kind reported in automobile crashes, says Lund, and are most likely to occur in rear impacts. Whiplash is the most serious injury reported in about two million U.S.-based insurance claims each year, which cost at least US$8.5 billion. "Such injuries aren't life-threatening," Lund admits, "but they can be painful and debilitating."
Rear-end crashes are common events in urban and suburban traffic, the IIHS has found.
When a vehicle is struck in the rear and driven forward, Lund explains, the vehicle seats accelerate occupants' torsos forward. Unsupported, their heads will lag behind the forward movement of their torsos. This differential motion causes the neck to bend back and stretch. The higher the torso acceleration the more sudden the motion, the higher the forces on the neck, and the more likely a neck injury is to occur.
"The key to reducing neck injury risk is to keep the head and torso moving together," Lund says. "To ensure this happens, a seat and head restraint have to work in concert to support the head, accelerating it with the torso as the vehicle is driven forward in a rear impact. This means the geometry of a head restraint has to be adequate, and so do the stiffness characteristics of the vehicle seat and head restraint."
A head restraint should extend at least as high as the top of the ears of the tallest expected occupant, Lund says. A restraint also should be positioned close to the back of an occupant's head so it can contact the head and support it early in a rear-end crash.
"But good head restraint geometry by itself isn't sufficient," Lund says. "A seat has to be designed so it doesn't move backward and away from the head during a rear impact. A seat also needs to 'give' so an occupant will sink into it, moving the head closer to the restraint."
Neck injuries are the most common kind reported in automobile crashes, says Lund, and are most likely to occur in rear impacts. Whiplash is the most serious injury reported in about two million U.S.-based insurance claims each year, which cost at least US$8.5 billion. "Such injuries aren't life-threatening," Lund admits, "but they can be painful and debilitating."
Rear-end crashes are common events in urban and suburban traffic, the IIHS has found.
When a vehicle is struck in the rear and driven forward, Lund explains, the vehicle seats accelerate occupants' torsos forward. Unsupported, their heads will lag behind the forward movement of their torsos. This differential motion causes the neck to bend back and stretch. The higher the torso acceleration the more sudden the motion, the higher the forces on the neck, and the more likely a neck injury is to occur.
"The key to reducing neck injury risk is to keep the head and torso moving together," Lund says. "To ensure this happens, a seat and head restraint have to work in concert to support the head, accelerating it with the torso as the vehicle is driven forward in a rear impact. This means the geometry of a head restraint has to be adequate, and so do the stiffness characteristics of the vehicle seat and head restraint."
A head restraint should extend at least as high as the top of the ears of the tallest expected occupant, Lund says. A restraint also should be positioned close to the back of an occupant's head so it can contact the head and support it early in a rear-end crash.
"But good head restraint geometry by itself isn't sufficient," Lund says. "A seat has to be designed so it doesn't move backward and away from the head during a rear impact. A seat also needs to 'give' so an occupant will sink into it, moving the head closer to the restraint."