For the first time the Insurance Institute for Highway Safety has evaluated the performance of minivans in side impact crash tests. The tests simulate crashes in which SUVs or pickup trucks strike the sides of minivans. These are the kinds of crashes that can occur at intersections when a vehicle runs a red light or stop sign.
Three minivans with standard side airbags — Toyota Sienna, Nissan Quest, and Honda Odyssey — earned the Institute's highest rating of good (side airbags were optional in the 2005 Sienna). The Sienna and Quest earned the added designation of "best pick" for side crash protection. The Sienna also is a "best pick" in the Institute's frontal offset test, so this minivan with side airbags is a "double best pick" for front and side crashworthiness.
The Ford Freestar with optional side airbags earned a rating of acceptable. When the Freestar and Mazda MPV were tested without their optional side airbags, both earned the lowest rating of poor (the MPV with optional side airbags wasn't tested; see note below).
These ratings reflect performance in a side impact crash test in which a moving deformable barrier strikes the driver side of a passenger vehicle at 31 mph. The barrier weighs 3,300 pounds and has a front end that is shaped like the front of a typical pickup or SUV. In each side-struck vehicle are two instrumented dummies the size of a small (5th percentile) woman, one positioned in the driver seat and one in the rear seat behind the driver.
The Institute didn't test the Chevrolet Uplander or the Dodge Grand Caravan/ Chrysler Town & Country minivans because design changes intended to improve their performance in side impact crashes are under way. The Institute will test these vehicles plus the redesigned Kia Sedona early next year.
"The risk of dying in frontal crashes has been reduced dramatically in recent years," says Institute chief operating officer Adrian Lund. "But there haven't been the same risk reductions in side impact crashes. We expect this test to drive manufacturers to make side airbags with head protection standard and improve side structures to better protect occupants in side impacts."
Federal test doesn't reflect many real-world crashes: The federal government also conducts side impact tests for consumer information but uses a barrier that was designed in the 1980s when cars represented most vehicles on the road. The height of the barrier's front end is below the heads of the dummies that measure injury risks in side-struck vehicles. The federal test doesn't assess the risks of head injury from impacts with vehicles like SUVs and pickups.
Federal moving deformable barrier
IIHS moving deformable barrier
The changed vehicle mix and high risks to people in 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 an SUV or pickup. The result is a barrier that's taller and higher off the ground.
All of the minivans in this round of tests performed well, earning four or five stars, in the government's side impact test. In contrast, the range of performance in the Institute's test indicates significant differences in how well these vehicles would protect their occupants in crashes with SUVs or pickups. Since SUVs and pickups now make up nearly half of new passenger vehicle sales each year, the type of crash simulated in the Institute's test is becoming more common.
Top performers have side airbags and structures that resist major intrusion: The minivans that earned good ratings in the side test are equipped with curtain-style airbags designed to protect the heads of people in all three rows of seats.
"In each of the top-performing minivans, the curtain airbags did a good job of keeping the dummies' heads from being struck by the intruding barrier," Lund says. "This is important because head injuries are factors in many serious side impact crashes, especially when the striking vehicle is a pickup or SUV with a tall front end. Manufacturers should follow the lead of Honda, Nissan, and Toyota in making head-protecting side airbags standard in their minivans. Important safety equipment like this shouldn't be optional."
The good performers also have side structures that resist major intrusion into the occupant compartment.
MPV and Freestar without side airbags are poor: In the test of the MPV, the driver dummy's head was struck by the intruding barrier. This didn't produce high injury measures, but head hits with intruding objects such as other vehicles, trees, or poles should be prevented.
"Plus the MPV's structure was marginal, so there was more intrusion that contributed to high forces on other parts of the dummies," Lund points out. "In a crash of similar severity in the real world, it's likely that a driver would suffer internal organ injuries as well as rib fractures. The rear passenger possibly would sustain a fractured pelvis."
In the Freestar without side airbags, the barrier came close to hitting the driver dummy's head. This indicates that only slightly different crash circumstances could produce a direct hit to a person's head. The Freestar's structure also is poor, which in the absence of optional side airbags contributed to high forces on the driver dummy's chest.
Note: The Mazda MPV does have optional combination side airbags designed to protect the torsos and heads of front-seat occupants, but when side airbags are optional the Institute tests vehicles without this option. If a manufacturer selling this option requests the Institute to conduct an additional test with the option and agrees to reimburse the Institute for the cost of the vehicle, a second test is conducted. Mazda didn't request such a test of the MPV. Ford requested a test of the Freestar with optional curtain-style airbags. Nissan requested a test of the Quest with optional torso airbags in addition to standard curtain airbags. Both Quests are good performers and "best picks."
Side airbags reduce risks in real-world crashes: Almost 10,000 passenger vehicle occupants die each year in side impacts, and head injuries are a leading cause. Institute research shows that side airbags with head protection are reducing deaths by about 45 percent among drivers of cars struck on the driver side. Before the availability of head-protecting airbags, there was virtually nothing to prevent people's heads from being struck by intruding vehicles or rigid objects like trees or poles in serious side impacts. Side airbags that protect the chest and abdomen, but not the head, also are reducing deaths but are less effective (about a 10 percent reduction in deaths).
How vehicles are evaluated: The Institute's frontal crashworthiness evaluations are based on results of frontal offset crash tests at 40 mph. Each vehicle's overall evaluation is based on three aspects of performance — measurements of intrusion into the occupant compartment, injury measures from a Hybrid III dummy positioned in the driver seat, and analysis of slow-motion film to assess how well the restraint system controlled dummy movement during the test.
Each vehicle's overall side evaluation is based on injury measures recorded on two instrumented SID-IIs dummies, assessment of head protection countermeasures, and the vehicle's structural performance during the impact. Injury measures obtained from the two dummies, one in the driver seat and the other in the rear seat behind the driver, are used to determine the likelihood that a driver and/ or passenger in a real-world crash would have sustained serious injury to various body regions. The movements and contacts of the dummies' heads during the crash also are evaluated. This assessment is more important for seating positions without head-protecting airbags which, assuming they perform as intended, should prevent injurious head contacts. Structural performance is based on measurements indicating the amount of B-pillar intrusion into the occupant compartment. Some intrusion into the compartment is inevitable in serious side impacts, but any intrusion that does occur should be uniform both horizontally and vertically and shouldn't seriously compromise the driver or passenger space.