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Status Report, Vol. 38, No. 7 | SPECIAL ISSUE: SIDE IMPACT CRASHWORTHINESS | June 28, 2003 Subscribe

First side impact testsHow 12 small SUVs fared

For the first time, the Insurance Institute for Highway Safety has evaluated vehicles in side impact crash tests to provide consumer information. The best performers among the 12 small SUVs tested (2003 models) are the Subaru Forester and the Ford Escape with optional side airbags.

In contrast, 7 other small SUVs earned the lowest rating of poor — the Escape without optional side airbags, Toyota RAV4, Suzuki Grand Vitara/Vitara/Chevrolet Tracker, Land Rover Freelander, Mitsubishi Outlander, Saturn VUE, and Honda Element. The Jeep Wrangler and Honda CR-V are rated marginal, and the Hyundai Santa Fe is acceptable.

The Subaru Forester is the only one of the 12 small SUVs to earn a good rating in both the side impact crashworthiness evaluation and the Institute's frontal offset crash test.

The side impact test represents what happens when a passenger vehicle is struck in the side by a pickup truck or SUV at about 30 mph. The results of this test expand the Institute's program of crash tests for consumer information. For eight years the Institute has been providing comparative rankings of passenger vehicles based on performance in frontal offset crash tests at 40 mph. Now most new passenger vehicles are being designed to earn good ratings in this test.

"Our side impact test is severe," says Institute president Brian O'Neill. "Given the designs of today's vehicles, it's unlikely that people in real-world crashes as severe as this would emerge uninjured. But with good side impact protection, people should be able to survive crashes of this severity without serious injuries."

O'Neill adds that he expects this new crashworthiness evaluation program to influence consumers' car-buying choices. "This is what happened with our frontal crash test results, and now we expect consumers will use the new test results to help them choose vehicles with good occupant protection in both front and side impacts."

Because consumers pay attention to the Institute's crash test results, automakers are expected to upgrade their vehicles' side impact protection, just as they've upgraded the protection their vehicles offer in frontal crashes.

"Ideally, passenger vehicles should be good performers in both tests — a double good," O'Neill says.

The configuration of the Institute's side impact test is a 31 mph perpendicular impact into the driver side of a passenger vehicle. The moving deformable barrier that strikes the test vehicle weighs 3,300 pounds and has a front end shaped to simulate the typical front end of a pickup or SUV. In each side-struck vehicle are two instrumented dummies, one in the driver seat and one in the rear seat behind the driver. These dummies are the size of a short (5th percentile) woman or a 12-year-old child.

"This is the first consumer information test program in the United States to use a dummy that represents small females," O'Neill points out.

Forester is best and Outlander is worst

The side airbag in the Subaru Forester kept the injury measures recorded on the driver dummy relatively low. The dummy in the rear seat also recorded relatively low measures, although its head did hit the pillar behind the back door — an area required by federal standard to limit head impact forces. There was somewhat less intrusion into the Forester than into several of the other small SUVs the Institute tested.

The Ford Escape with optional side airbags also is rated good. However, it was only a marginal performer in the Institute's frontal offset crash test.

In contrast, the Mitsubishi Outlander was the worst performer in the side impact test. There was more intrusion into the occupant compartment than in many of the other vehicles tested. The Outlander that was tested didn't have side airbags. The barrier struck the driver dummy's head, and injury measures recorded on the head as well as on the torso and pelvis were very high.


Crashworthiness evaluations

Side Front
Subaru Forester
G
G
Hyundai Santa Fe
A
G
Honda CR-V
M
G
Ford Escape/Mazda Tribute with side airbags
G
M
Escape/Tribute without side airbags
P
M
Jeep Wrangler
M
A
Honda Element
P
G
Saturn Vue
P
G
Mitsubishi Outlander
P
G
Land Rover Freelander
P
A
Suzuki Grand Vitara/Vitara/Chevrolet Tracker
P
A
Toyota RAV4
P
A
GOOD
G
ACCEPTABLE
A
MARGINAL
M
POOR
P

How the small SUVs are evaluated

Each vehicle's overall side impact evaluation is based on (1) injury measures recorded on the two instrumented SID-IIs dummies, (2) assessment of head protection countermeasures, and (3) each vehicle's structural performance during the impact.

(1) Injury measures are obtained from two SID-IIs dummies, one in the driver seat and the other in the rear seat behind the driver. These measures are used to determine the likelihood that a driver and/or passenger would have sustained serious injury to various body regions. Measures are recorded from the head, neck, chest, abdomen, pelvis, and leg. These injury measures, especially those from the head/neck and torso (chest and abdomen), are major components of each vehicle's overall evaluation.

(2) To supplement head injury measures, researchers evaluate the movements and contacts of the dummies' heads during the crash. This assessment is more important for seating positions without head protection airbags, which (assuming they perform as intended) should prevent injurious head contacts. Very high head injury measures typically are recorded when the moving deformable barrier hits a dummy's head during impact. However, a "near miss" or a grazing contact also indicates a potential risk of serious injury in a real-world crash. This is because small differences in occupants' heights or in their seating positions compared with the test dummies could result in a hard contact and high risk of serious head injury. In the rear seat, the potential for serious injury is influenced by whether the seating position puts occupants' heads in proximity to areas designed with padding or something else to reduce impact forces versus areas with hard or unprotected structures.

Analysis of the movement and contact points of the dummies' heads during the crash test is used to assess this aspect of protection.

(3) Structural performance is based on measurements indicating the amount of intrusion into the occupant compartment around the B-pillar (between the doors). This assessment indicates how well a vehicle's side structure resisted intrusion into the driver and rear-seat passenger space. Some intrusion into the compartment is inevitable in serious side impacts. Any intrusion that does occur should be uniform both horizontally and vertically and shouldn't seriously compromise the driver and passenger space. Less intrusion helps assure that other occupants of sizes and in seating positions different from the dummies also would have lower injury risks.

These three factors determine each vehicle's overall side crashworthiness evaluation. The order in which the vehicles are listed depends on performance in the Institute's frontal offset crash test as well as the side impact test.

Since 1997 the federal New Car Assessment Program, which compares crashworthiness among new passenger vehicles, has included side impacts. In these tests, an impactor with a deformable front end representing the front of a car is used to strike the sides of the vehicles being assessed.

This moving deformable barrier was developed in the early 1980s, when cars represented most of the vehicles on the road. The height of the barrier's front end is below the heads of the dummies that measure injury risks in the side-struck vehicles. These federal tests don't assess the risks of head injury from impacts with vehicles like SUVs or pickups.

The changed vehicle mix and high risks to occupants of side-struck vehicles when the striking vehicles are SUVs or pickups led the Institute to modify the moving deformable barrier used in the federal test so the front end represents the geometry of a typical SUV or pickup. The result is a barrier that's higher off the ground, taller, and contoured.

The design of this barrier and choice of test speed (31 mph) reflect extensive developmental tests, including tests comparing the results from side impacts with barriers versus side impacts with SUVs and pickups.

Another difference between Institute and federal side impact tests involves the choice of test dummies. The Institute uses SID-IIs dummies, which are smaller than the dummy (SID) used in the federal government's test. SID-IIs is a newer design than SID, which was developed in the 1970s, and it records more injury measures across more body regions.

SID-IIs represents a small (5th percentile) female or a 12 year-old. This choice of dummies reflects the fact that women are more likely than men to suffer serious head injuries in real-world side impacts. The head of the smaller SID-IIs driver dummy is in the window area where people's heads are more vulnerable to being struck by the front end of a striking vehicle in a real-world side impact.


SID: The side impact test dummy (SID) represents an average-size male. Developed in the 1970s, SID principally is used to measure acceleration in the chest (rib cage and spine) during the test. It doesn't measure chest compression. Nor is there any measure of injury risk in the abdomen or leg.

Federal side impact test: The front of the moving deformable barrier represents vehicle designs of the early 1980s. The barrier travels toward the test vehicle along a "crabbed," or angular, path at a speed that simulates a two-vehicle intersection collision in which the striking vehicle is going 34 mph and the struck vehicle is going 17 mph.

SID-IIs: The Institute's side impact test dummy, called SID-IIs, represents a small woman or a 12 year-old. The chest of SID-IIs measures compression as well as acceleration, and this test dummy records injury risk in the abdomen, pelvis, and leg.

IIHS side impact test: The moving deformable barrier is higher off the ground and taller than in the federal test. The barrier's front end represents the front of a pickup or SUV. It travels toward the test vehicle along a perpendicular path instead of "crabbed," as in the federal test (a difference that has little effect on injury measures, according to developmental tests).


Federal side impact test

The front of the moving deformable barrier represents vehicle designs of the early 1980s. The barrier travels toward the test vehicle along a "crabbed," or angular, path at a speed that simulates a two-vehicle intersection collision in which the striking vehicle is going 34 mph and the struck vehicle is going 17 mph.

The side impact test dummy (SID) represents an average-size male. Developed in the 1970s, SID principally is used to measure acceleration in the chest (rib cage and spine) during the test. It doesn't measure chest compression. Nor is there any measure of injury risk in the abdomen or leg.

Institute side impact test

The moving deformable barrier is higher off the ground and taller than in the federal test. The barrier's front end represents the front of a pickup or SUV. It travels toward the test vehicle along a perpendicular path instead of "crabbed," as in the federal test (a difference that has little effect on injury measures, according to developmental tests).

The Institute's side impact test dummy, called SID-IIs, represents a small woman or a 12 year-old. The chest of SID-IIs measures compression as well as acceleration, and this test dummy records injury risk in the abdomen, pelvis, and leg.

The design of the moving deformable barrier used in the Institute's side impact crash test reflects extensive developmental testing. This research included a pair of tests, one in which the barrier hit the side of a Ford Focus (above left) and another in which a Ford Explorer (midsize SUV) hit the side of a Focus. Damage patterns were similar, indicating the barrier does a good job of representing the damage inflicted by SUVs and pickups in real-world crashes.

Barrier into Ford Focus

Ford Explorer into Ford Focus

The design of the moving deformable barrier used in the Institute's side impact crash test reflects extensive developmental testing. This research included a pair of tests, one in which the barrier hit the side of a Ford Focus (above left) and another in which a Ford Explorer (midsize SUV) hit the side of a Focus. Damage patterns were similar, indicating the barrier does a good job of representing the damage inflicted by SUVs and pickups in real-world crashes.

SIDEBAR
Head protection is key

Head injuries are a leading cause of death in side crashes. Head-protecting side airbags can help.

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