Tougher IIHS Crash Tests Mean Safer Cars

New Safety Technologies Demand More Stringent Testing


  • IIHS Crash Test - Frontal Impact

    IIHS Crash Test - Frontal Impact

    Frontal-offset and side-impact crash tests demonstrate how much vehicles deform even at lower-than-normal highway speeds. | March 18, 2010

7 Photos

The estimated 39,800 people killed on U.S. roads in 2008 represent thousands more who mourn their unnecessary deaths. Yet the government looks at these 39,800 deaths as an improvement, because even with more vehicles on the road and more miles being driven, actual death rates are declining. A historical look at vehicle safety ratings shows how much safer cars have become over time. But to keep fatality figures headed in a downward direction, crash tests — which are key in proving what actually works — are getting tougher.

The private Insurance Institute for Highway Safety (IIHS) is a major vehicle tester and issues its own vehicle safety ratings. The IIHS was first to revamp its tests to replicate collisions with SUVs and trucks. In fact, the big testing overhaul coming from the National Highway Traffic and Safety Administration (NHTSA) was likely inspired by the changes the IIHS had made to its tests. The institute revises its tests to keep up with real-world road conditions, and has also made electronic stability control (ESC) a requirement for any vehicle that wants to be a "Top Safety Pick," the IIHS's top rating. In 2008, the Toyota Tundra became the first pickup truck to earn that status due in part to its inclusion of ESC and side airbags as standard features.

IIHS Tests
IIHS crash testing includes frontal offset crash tests, side-impact tests and rear collision tests that evaluate seat/head restraints, and new low-impact bumper tests. The IIHS ranks vehicles "Good," "Acceptable," "Marginal" or "Poor."

The IIHS created its top safety picks in 2006. Top picks must receive a "Good" rating in three institute tests and must offer electronic stability control. Winners for the 2009 model year included the Acura MDX, Ford Fusion and Volkswagen Passat.

Frontal Offset Crash
Frontal offset crashes are a lower percentage of total frontal crashes but they are more dangerous because they cause structural damage that can penetrate the cabin. That's because a smaller area of the structure must manage the full crash energy.

The IIHS crashes the driver side of a vehicle's front end at an offset angle into a deformable barrier at 40 mph. The forces are similar to those involved in a frontal offset crash between two vehicles of the same weight or size, each going just less than 40 mph. "We're looking at adding another evaluation to our crash tests," said Adrian Lund, president of the IIHS. "We have done a good job with frontal crashes, but there's more work to do in other areas such as rollover."

The institute now allows manufacturers to do their own frontal impact testing on refreshed versions of previous models that have earned top ratings. It will issue ratings based on manufacturers' tests and conduct audits to verify manufacturers' results. The IIHS continues its testing of substantially redesigned vehicles.

Being chosen as an IIHS "Top Safety Pick" is a boast-worthy title for a vehicle. The toughening of the IIHS tests, along with the federal mandates, has prompted many automakers to improve their seats and head restraints and to add more standard safety equipment to their models. These improvements have caused everyone to score better across the board. For the 2009 model year, there were 72 models chosen as "Top Safety Picks" — twice as many as in 2008 and about three times as many as in 2007.

Side Impact
The IIHS introduced its side-impact test in 2003. It uses a contoured moving barrier weighing 3,300 pounds that crushes on impact to mimic a crash with an SUV. The barrier strikes the driver side of a passenger vehicle on a perpendicular angle at 31 mph. Two dummies are placed in the vehicle: One is positioned in the driver seat; the other, representing an adolescent, is positioned in the rear seat behind the driver.

This was the first consumer test program to use a female dummy. Women tend to sit closer to the steering wheel, which places their heads in the middle of the side window. This makes them susceptible to serious head injury in a side impact. Men, who sit farther back, are protected by a vehicle's B-pillar (center pillar).

The use of a smaller dummy could push designers of side airbags to offer better protection for smaller drivers.

Rear Collision Tests
In the IIHS's rear collision procedure, seat/head restraints are measured to ensure that they fit the heads and necks of different-size occupants. Those that meet the requirements go on to the sled test.

The sled test uses a special dummy with a flexible spine, belted into a vehicle seat. The seat runs on rails fixed to a movable steel platform to simulate a stationary vehicle being struck from the rear at 20 mph by a vehicle of similar weight. It re-creates the effects of acceleration on occupants during a crash.

According to the IIHS, 26 out of 180 eligible vehicles fell short of earning a Top Safety Pick in 2009 because of inadequate head-restraint designs.

Accident Prevention, Active Safety Systems
Both the IIHS and NHTSA are testing active safety systems. These systems decide an accident is coming and jam on the brakes or adjust head restraints and tighten seatbelts. Newer systems give you a warning, to which you must respond. They include lane departure warnings (vibrating seats and steering wheels or beeping) and collision avoidance systems. They differ from passive systems like airbags that aim to protect once an accident has occurred.

The best of the active safety systems is ESC. The most significant safety advance since seatbelts, ESC uses electronic sensors to help control a vehicle's direction and keep it on course. It's particularly effective at preventing rollovers. The government has mandated the system for all cars sold in the U.S. by the 2012 model year.

"These new technologies could prevent some of the fatalities, but we need to sort through which of these ideas are actually going to work," says the IIHS's Lund. "When you change the driving task, you have to find out if drivers will pay attention and how behavior will change."

Although the new features aren't in enough vehicles to fully predict their effectiveness, the IIHS has found that forward collision warning and lane departure warning have shown great potential to prevent or reduce the severity of relevant crashes.

Front and Rear Bumper Tests
Front and rear bumper low-speed collisions occur when vehicle bumpers slide under or over each other. Braking before impact can lower the front end of a striking vehicle just before it hits the other vehicle. Bumper incompatibility can cause costly damage to vehicle grilles, headlights, hoods and fenders.

The IIHS performs four bumper tests to replicate low-speed collisions: front and rear full-width impacts at 6 mph and front and rear corner impacts at 3 mph. A vehicle is run into a barrier that's designed to mimic a car bumper that is 18 inches off the ground in the full-width tests and 16 inches from the ground in the corner impacts. The IIHS pointed out that even if they do hit the bumper of the vehicle they crash into head-on, the bars underneath bumper covers often aren't up to absorbing the energy. This can cause more damage to other parts of the vehicle and increase the cost of repairs. The Ford Focus stood out as an example of a reasonably good bumper design, while the bumper on the Toyota Prius was found to be too low to protect the taillights and rear hatch from damage in an accident. These tests are not included in the IIHS's top safety rankings, but the institute is considering developing a separate score.

Roof Strength Rating System
In early 2009 the IIHS introduced its roof strength rating system. Vehicles rated "good" must have roofs that are more than twice as strong as the minimum federal safety standard.

In the test, a metal plate pushes against one side of the roof at a constant speed. To earn a good rating, the roof must withstand a force of four times the vehicle's weight before being crushed five inches deep. This is called a strength-to-weight ratio. For an acceptable rating, the minimum required strength to-weight ratio is 3.25. A marginal rating value is 2.5. Anything lower than that is poor.

Twelve small SUVs were the included the inaugural test. As a testament to their rigorous testing, only four earned the top rating of "good".

Specific IIHS vehicle safety ratings are available at the IIHS Web site. Safety ratings and features for any car are also listed in the Edmunds Safety Index by car name.

Related Articles:
Protect Your Neck: Warding off Whiplash With Head Restraints
Crash Tests: Feds Raise the Bar on Car Safety

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