Frontal offset crash test details
Ratings criteria
Crash test verification
Today's passenger vehicles are designed to be more crashworthy than they used to be. Still, about 30,000 passenger vehicle occupants die in crashes on US roads each year. About half of the deaths occur in frontal crashes.
Since the late 1970s, the federal New Car Assessment Program has compared frontal crashworthiness among new passenger vehicles. This program, which involves 35 mph crash tests into a full-width rigid barrier, has been highly successful in providing consumers with comparative crashworthiness information. It also has been a major contributor to the crashworthiness improvements that characterize recent passenger vehicle models.
The very success of the New Car Assessment Program means remaining differences in performance among most new vehicles in full-width tests are small. This doesn't mean important crashworthiness differences no longer exist. They do exist, and additional crash test configurations can highlight these differences. One such test is the frontal offset crash.
Full-width and offset tests complement each other. Crashing the full width of a vehicle into a rigid barrier maximizes energy absorption so that the integrity of the occupant compartment, or safety cage, can be maintained well in all but very high-speed crashes. Full-width rigid-barrier tests produce high occupant compartment decelerations, so they're especially demanding of restraint systems. In offset tests, only one side of a vehicle's front end, not the full width, hits the barrier so that a smaller area of the structure must manage the crash energy. This means the front end on the struck side crushes more than in a full-width test, and intrusion into the occupant compartment is more likely. The bottom line is that full-width tests are especially demanding of restraints but less demanding of structure, while the reverse is true in offsets.
The Institute began frontal offset crash testing in 1995. In the Institute's 40 mph offset test, 40 percent of the total width of each vehicle strikes a barrier on the driver side. The barrier's deformable face is made of aluminum honeycomb, which makes the forces in the test similar to those involved in a frontal offset crash between two vehicles of the same weight, each going just less than 40 mph. Test results can be compared only among vehicles of similar weight. Like full-width crash test results, the results of offset tests cannot be used to compare vehicle performance across weight classes. This is because the kinetic energy involved in the frontal test depends on the speed and weight of the test vehicle, and the crash is more severe for heavier vehicles. Given equivalent frontal ratings for heavier and lighter vehicles, the heavier vehicle typically will offer better protection in real-world crashes.
Ratings criteria
 Overall evaluation (frontal): The three factors evaluated
in the frontal offset crash test — structural performance, injury
measures, and restraints/dummy kinematics — determine each vehicle's
overall frontal offset crashworthiness evaluation. The order in which
vehicles are listed depends on performance in side impact tests as well
as frontal offset crash tests. Ideally vehicles should be good performers
in both test configurations — a double good. Head restraint and
bumper evaluations influence the rankings of vehicles with otherwise similar
overall crashworthiness performance.
Structure/safety cage: Structural performance is based on measurements indicating the amount and pattern of intrusion into the occupant compartment during the offset test. This assessment indicates how well the front-end crush zone managed the crash energy and how well the safety cage limited intrusion into the driver space. Intrusion is measured at 9 places in the driver seating area by comparing the precrash and postcrash positions of these 9 points. (The steering wheel intrusion is split into upward and rearward components to obtain a total of 10 measurements.) Larger intrusion numbers indicate more collapse of the safety cage. For more information about how these measurements are made and compared, read our
Performance of the structure/safety cage is a major component of each vehicle's overall evaluation.
Injury measures: Obtained from a 50th percentile male Hybrid III dummy in the driver seat, injury measures are used to determine the likelihood that a driver would have sustained injury to various body regions. The measures recorded from the head, neck, chest, legs, and feet of the dummy indicate the level of stress/strain on that part of the body. Thus, greater numbers mean bigger stresses/strains and a greater risk of injury. For more information about how these measurements are made and compared, read our
Like structural performance, this assessment also is a major component of each vehicle's overall evaluation.
Restraints/dummy kinematics (movement): Significant injury risk can result from undesirable dummy kinematics — for example, partial ejection from the occupant compartment — in the absence of high injury measures. This aspect of performance involves how safety belts, airbags, steering columns, head restraints, and other aspects of restraint systems interact to control dummy movement. For more information about how these measurements and judgments are made and compared, read our
Although this assessment is important, it doesn't contribute as much as structural performance or injury measures to each vehicle's overall evaluation.
Test verification
Verification ratings are based on 40 mph frontal offset crash tests conducted by manufacturers for vehicles meeting requirements established by the Institute. Manufacturers supply information on basic vehicle and test parameters, measurements of intrusion into the occupant compartment, injury data recorded on a dummy representing an average-size man in the driver seat, and video of the tests. Institute engineers review this information and rate vehicles based on the same evaluation parameters used for the Institute's frontal offset test. To ensure manufacturers' good faith participation, the Institute is conducting audit tests.
Only redesigned vehicles with immediate predecessors that earned the top rating of good in previous Institute tests are eligible for the verification approach. Substantially redesigned vehicles with significant changes in size, weight, or body style aren't eligible. The Institute will continue testing these vehicles.
The verification approach assures that automakers still pay attention to offset crash protection as they redesign their vehicles and introduce new ones. This approach is possible because of the manufacturers' actions during the past decade. They have incorporated offset crash test performance plus government-required and other consumer information crash testing into their guidelines. They routinely conduct their own offset tests during the design process.
Recognizing this effort, the verification approach goes a step beyond an Institute policy in place since the beginning of the frontal test program. Manufacturers always have been asked to confirm whether the Institute's ratings could be carried over from one model year to the next. Based on this information, the Institute has been carrying over ratings for vehicles with no significant design changes.
Frontal offset crash tests conducted by the Institute since 1995 have prompted huge improvements in how vehicles protect people in frontal crashes.
When the Institute began evaluating frontal crashworthiness by vehicle group, beginning in the mid-1990s, about half of the vehicles that were tested earned marginal or poor ratings. More were rated poor than good.
Then manufacturers responded by changing the designs of their vehicles to improve frontal crashworthiness. The result has been a turnaround in the frontal ratings. Now virtually every current passenger vehicle design the Institute has evaluated earns good ratings.
The Institute's test primarily assesses how well a vehicle's front-end crush zone absorbs energy during a crash and, in turn, how well the occupant compartment, or safety cage, holds together. If the compartment remains largely intact, then the restraint systems can control the motion of the crash test dummy and help keep injury measures low. But if there's significant deformation of the safety cage and intrusion into the compartment, then the restraint systems are less likely to keep the measures low. Newer vehicles have much stronger occupant compartments, in large part because of the steps automakers have taken in the past decade to earn good ratings in the Institute's frontal tests. Frontal crash test verification will ensure that these gains are maintained. |
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