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Study Gives Ratings for Head Restraints and Seat Belts in SUVs, Pickup
Trucks and Minivans
http://www.ohsonline.com/articles/49003
THE
designs of seats and head restraints in 21 current SUV, pickup and
minivan models are rated good for protecting people in rear impacts, but
those in 54 other models are rated marginal or poor. Another 12 are
rated acceptable.
The latest evaluations of occupant protection in rear-end collisions by
the Insurance Institute for Highway Safety found that the seat/head
restraints in more than half of light truck and minivan models fall
short of state-of-the-art protection from neck injury or whiplash.
The ratings for 87 current models are based on geometric measurements of
head restraints and simulated crashes that together assess how well
people of different sizes would be protected in a typical rear crash.
Among the best performers are the seat/head restraint combinations in
SUVs made by Subaru and Volvo and new designs from Acura, Ford, Honda
and Hyundai. Seat/head restraints in three minivan models from Hyundai
and Ford earn good ratings. The redesigned Toyota Tundra is the only
pickup model evaluated with seat/head restraints rated good for rear
crash protection.
"In stop and go commuter traffic, you're more likely to get in a
rear-end collision than any other crash type," said David Zuby, senior
vice president of the institute's
Rear-end collisions are frequent, and neck injuries are the most common
injuries reported in auto crashes. They account for 2 million insurance
claims each year, costing at least $8.5 billion. Such injuries aren't
life-threatening, but they can be painful and debilitating.
Good seat/head restraint designs keep people's heads and torsos moving
together: When a vehicle is struck in the rear and driven forward, its
seats accelerate occupants' torsos forward. Unsupported, an occupant's
head will lag behind this forward torso movement, and the differential
motion causes the neck to bend 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 whiplash injury risk is to keep the head and torso
moving together, the institute stated. To accomplish this, the geometry
of a head restraint has to be adequate -- high enough to be near the
back of the head. Then the seat structure and stiffness characteristics
must be designed to work in concert with the head restraint to support
an occupant's neck and head, accelerating them with the torso as the
vehicle is pushed forward.
In the latest evaluations, the seat/head restraint combinations in 17 of
59 SUV models are rated good, five are acceptable, 14 are marginal, and
23 are rated poor. In minivans, seat/head restraints in three models are
rated good, two are acceptable, one is marginal, and five are rated
poor. In pickups one is good, five are acceptable, five are marginal,
and six are rated poor.
While there hasn't been much overall improvement among pickups and
minivans since the last time the institute evaluated protection in rear
crashes, the performance of the seat/head restraints in SUVs is much
better. In 2006 those in only six of 44 SUV models earned a good rating.
"The reason may be that automakers have updated or introduced many new
SUVs since 2006, but minivans and pickups are being updated more
slowly," Zuby stated.
In the latest tests seat/head restraints in the Mitsubishi Outlander
improved to good from the previous design that was rated acceptable.
Those in the Acura MDX, Honda CR-V, Honda Element, Hyundai Santa Fe and
Kia Sorento improved from their previous ratings of poor to good. Those
in the Honda Pilot and Mercedes M class improved from marginal to good.
The seat/head restraints in the Toyota Tundra pickup improved to good
from acceptable.
In contrast some manufacturers have introduced new models with subpar
seat designs, the institute stated. The ones in the BMW X5, Dodge Nitro,
and Suzuki XL7 are rated poor. Those in the new Mazda CX-7 and CX-9 are
rated marginal.
Among the poor-rated seats in the new evaluations, those in seven models
didn't make it to the testing stage because the geometry of their head
restraints is marginal or poor. This means they can't be positioned to
protect many taller people, so the institute doesn't test them. Among
these lowest rated seats are those in the Cadillac SRX SUV, Nissan Quest
minivan and Ford Ranger pickup.
Safety ratings and government rules are driving the changes: Some
manufacturers are making changes to the seat/head restraint designs in
their vehicles to earn the institute's "Top Safety Pick" award. Other
improvements are being spurred by changes to federal safety rules.
Front-seat head restraints will have to extend higher and fit closer to
the backs of people's heads under a rule issued by the National Highway
Traffic Safety Administration in 2004. Originally set to go into effect
for front-seat head restraints in September 2008, the agency recently
delayed the effective date in response to petitions for reconsideration.
Under the new phase-in schedule, manufacturers must start to fit better
front-seat head restraints in 80 percent of their models beginning in
September 2009. Front-seat head restraints in all new vehicles made
after September 2010 must comply.
"There's lots of room for improvement in the designs of seats and head
restraints," Zuby said. "We know many manufacturers are trying to fit
better head restraints in their vehicles, and some have been working
with us to boost their ratings as they introduce new models. Some
manufacturers were waiting for resolution of regulatory issues before
fitting better designs in their vehicles. And some didn't get changes
made in time for the Institute's tests. For example, BMW plans to
redesign the seats in the X5 and X3 SUVs to earn better ratings for the
2008 model year."
For more information, contact the institute at
http://www.iihs.org.
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