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Status Report, Vol. 36, No. 1 | SPECIAL ISSUE: HEAD PROTECTION IN SIDE IMPACTS | January 6, 2001 Subscribe

Institute crash tests show value of head-protecting side airbags

You could survive a severe crash like this because of new technology — side airbag head protection. Many cars, including not only luxury models but also some popular and less expensive cars, are being equipped with side airbags designed to protect people's heads. New Institute crash tests of the BMW X5 and Volvo S80 — car-into-pole and vehicle-to-vehicle tests — demonstrate the important benefits afforded to occupants by these side airbag head protection systems.

Pickup truck into side of Volvo S80

The Institute conducted two crash tests in which the fronts of Chevrolet pickup trucks struck the sides of 1999 Volvo S80s. The S80 in one test included side airbag head protection, while in the other test the S80 didn't (both S80s had side airbags for torso protection). In each test, the pickup was going 32 mph, the S80 16 mph. Results show the head airbags provide very important protection in addition to what is afforded by the torso bags.

In the test without the head protection airbag, the heads of the driver and rear passenger dummies were struck by the hood of the pickup truck. The forces recorded on the rear-seat dummy's head were high — in fact, sufficient to cause fatal head injuries. The driver dummy's head contact didn't produce high forces, but the fact that the contact occurred means the head barely escaped severe impact. In contrast, in the test with the head protection airbag both dummies recorded low head forces because the inflatable curtain provided a cushion between the dummies' heads and the hood of the pickup truck.

Injury measures taken from the dummies' torsos were similar in the two Volvo S80s, with and without head protection. In both cars, these measures were low except for abdomen compression on the rear-seat dummies, which were at levels at which a person could sustain serious, though survivable, injuries to the spleen, kidney, or colon.

"These tests demonstrate that head airbags can make very serious vehicle-to-vehicle side impacts survivable by preventing the intruding vehicle structure from striking occupants' heads. Without head airbags, serious or fatal head injuries become more likely," says Institute president Brian O'Neill.

Pickup going 32 mph into Volvo S80 going 16 mph,
with and without side airbag head protection

With head protection Without head protection
Injury
reference value
Driver Rear
passenger
Driver Rear
passenger
Head injury criterion 700 140 561 167 1868
Neck compression (kN) -4.0 -0.49 -0.12 -0.39 -0.17
Neck tension (kN) 3.3 0.8 1.4 1.6 2.6
Thoracic trauma index (g) 85 56 75 66 67
Abdomen compression (mm) 39 46 46
Lateral pelvic acceleration (g) 130 70 47 79 49
Red: value exceeds threshold, indicated by injury reference, above which serious injury is increasingly likely. Note: SID H3 driver dummies are modified versions of the dummy specified in federal side impact tests. SID H3 s head and neck are from Hybrid III dummies. Rear-seat dummies are BioSIDs which, unlike SIDs, are specifically designed to measure both acceleration and compression of the chest and abdomen.

Car-into-pole crash tests

The Institute also conducted side-into-pole crash tests of a BMW X5 and Volvo S80, both equipped with side airbag head protection — an inflatable curtain in the Volvo and an inflatable tube-shaped airbag in the BMW. In each test, the vehicle was propelled sideways at 18 mph into a rigid pole.

The 18 mph speed of this test "might not sound like one at which a crash could be serious," O'Neill says, "but impacts into rigid objects such as poles or trees at 18 mph are, in fact, very severe." The intrusion into the X5 and S80 indicates the severity. The pole is relatively narrow, so there was major penetration into the side of each car. Yet the forces recorded on the dummies' heads in these tests were low.

This isn't the first time the Institute has tested a BMW with head protection airbags (see "Airbags for heads reduce injuries in side impact crashes," Dec. 27, 1997).

"All of these tests demonstrate that people can survive serious side impact crashes in the real world because head airbags prevent their heads from striking rigid objects," O'Neill says. He adds that "side airbags with head protection represent a very important safety development that will save lives and prevent major head trauma in a range of serious side impact crashes."

All four recent crash tests involving Volvos and a BMW were conducted in cooperation with the automakers.

BMW X5
Injury
reference value
Test result
2001 BMW X5 with side airbag head protection,
18 mph into pole

Head injury criterion 700 439
Neck compression (kN) -4.0 -0.47
Neck tension (kN) 3.3 1.5
Thoracic trauma index (g) 85 51
Abdomen compression (mm)
Lateral pelvic acceleration (g) 130 43
Note: test dummy (SID H3) doesn't record abdomen compression.
Injury
reference value
Test result
1999 Volvo S80 with side airbag head protection,
18 mph into pole

Head injury criterion 700 265
Neck compression (kN) -4.0 -0.16
Neck tension (kN) 3.3 1.0
Thoracic trauma index (g) 85 37
Abdomen compression (mm)
Lateral pelvic acceleration (g) 130 43
Note: test dummy (SID H3) doesn't record abdomen compression.
SIDEBAR
Real-world crashes show need for airbags

Many of the nearly 10,000 deaths that occur each year in side crashes are the result of head injuries. Side airbags with head protection could prevent many of them.

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