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Journal Article

Brake Burnishing Effect on AEB Performance

The Insurance Institute for Highway Safety (IIHS) evaluates autonomous emergency braking (AEB) systems as part of its front crash prevention (FCP) ratings. To prepare the test vehicles' brakes, each vehicle must have 200 miles on the odometer and be subjected to the abbreviated brake burnish procedure of Federal Motor Vehicle Safety Standard (FMVSS) 126. Other organizations conducting AEB testing follow the more extensive burnishing procedure described in FMVSS 135; Light Vehicle Brake Systems. This study compares the effects on AEB performance of the two burnishing procedures using seven 2014 model year vehicles. Six of the vehicles achieved maximum AEB speed reductions after 60 or fewer FMVSS 135 stops. After braking performance stabilized, the Mercedes ML350, BMW 328i, and Volvo S80 showed increased speed reductions compared with stops using brand new brake components.
Technical Paper

Structural Design Strategies for Improved Small Overlap Crashworthiness Performance

In 2012, the Insurance Institute for Highway Safety (IIHS) began a 64 km/h small overlap frontal crash test consumer information test program. Thirteen automakers already have redesigned models to improve test performance. One or more distinct strategies are evident in these redesigns: reinforcement of the occupant compartment, use of energy-absorbing fender structures, and the addition of engagement structures to induce vehicle lateral translation. Each strategy influences vehicle kinematics, posing additional challenges for the restraint systems. The objective of this two-part study was to examine how vehicles were modified to improve small overlap test performance and then to examine how these modifications affect dummy response and restraint system performance. Among eight models tested before and after design changes, occupant compartment intrusion reductions ranged from 6 cm to 45 cm, with the highest reductions observed in models with the largest number of modifications.
Technical Paper

Relationship between Pedestrian Headform Tests and Injury and Fatality Rates in Vehicle-to-Pedestrian Crashes in the United States

Pedestrian protection evaluations have been developed to encourage vehicle front-end designs that mitigate the consequences of vehicle-to-pedestrian crashes. The European New Car Assessment Program (Euro NCAP) evaluates pedestrian head protection with impacts against vehicle hood, windshield, and A-pillars. The Global Technical Regulation No. 9 (GTR 9), being evaluated for U.S. regulation, limits head protection evaluations to impacts against vehicle hoods. The objective of this study was to compare results from pedestrian head impact testing to the real-world rates of fatal and incapacitating injuries in U.S. pedestrian crashes. Data from police reported pedestrian crashes in 14 states were used to calculate real-world fatal and incapacitating injury rates for seven 2002-07 small cars. Rates were 2.17-4.04 per 100 pedestrians struck for fatal injuries and 10.45-15.35 for incapacitating injuries.
Technical Paper

Comparison of Hybrid III and THOR Dummies in Paired Small Overlap Tests

The Insurance Institute for Highway Safety (IIHS) is investigating small overlap crash test procedures for a possible consumer information program. Analysis of real-world small overlap crashes found a strong relationship between serious head and chest injuries and occupant compartment intrusion. The main sources of serious head injuries were from the A-pillar, dash panel, or door structure, suggesting head trajectories forward and outboard possibly bypassing the airbag. Chest injuries mainly were from steering wheel intrusion and seat belt loading. In developing this program, two test dummies were evaluated for predicting occupant injury risk: midsize male Hybrid III and THOR. In the collinear small overlap crash tests conducted here, results from the two dummies were similar. Both predicted a low risk of injury to the head and chest and sometimes a high risk of injury to the lower extremities. Head and torso kinematics also were similar between dummies.
Technical Paper

Evaluation of US Rear Underride Guard Regulation for Large Trucks Using Real-World Crashes

Current requirements for rear underride guards on large trucks are set by the National Highway Traffic Safety Administration in Federal Motor Vehicle Safety Standards (FMVSS) 223 and 224. The standards have been in place since 1998, but their adequacy has not been evaluated apart from two series of controlled crash tests. The current study used detailed reviews of real-world crashes from the Large Truck Crash Causation Study to assess the ability of guards that comply with certain aspects of the regulation to mitigate passenger vehicle underride. It also evaluated the dangers posed by underride of large trucks that are exempt from guard requirements. For the 115 cases meeting the inclusion criteria, coded data, case narratives, photographs, and measurements were used to examine the interaction between study vehicles. The presence and type of underride guard was determined, and its performance in mitigating underride was categorized.
Technical Paper

Measurement Error in Lateral Thoracic Deflection and Deflection Rate Due to Oblique Loading

Anthropometric test devices (ATDs) instrumented with potentiometers and accelerometers are used regularly to assess thoracic injury risk in side impact crash tests. Measurements from these sensors are compared with injury assessment reference values (IARVs) for lateral loading to establish the risk of injury for humans subjected to similar impacts. In crash tests, the deflections and deflection rates derived from these two types of sensors (potentiometers vs. accelerometers) have varying degrees of agreement. In some cases, differences can be relatively large. In the past, it was unclear whether the reason for the differences was off-axis loading that misaligned the accelerometers used in the calculation, an inherent inability of the potentiometer to capture high deflection rates under certain conditions, or some other phenomenon.
Technical Paper

Changes in Vehicle Designs from Frontal Offset and Side Impact Crash Testing

The Insurance Institute for Highway Safety (IIHS) has been conducting frontal offset crash tests of new passenger vehicles and providing comparative crashworthiness information to the public since 1995. This program has resulted in large improvements in frontal crashworthiness largely because vehicle structures have been redesigned to prevent significant collapse of the occupant compartment. In late 2002, IIHS began a side impact crash test program in which the side-impacting barrier has been designed to simulate the geometry of the front ends of SUVs and pickups, which pose a much larger threat in side impacts than the lower front ends of cars. It is anticipated that this program, too, will result in changes in vehicle structure, in this case the structure of the vehicle side pillars and door hardware. Good performance in the side impact test also is likely to require installation of side airbags (or comparable system) to protect the head and/or chest.
Technical Paper

Comparison of EuroSID-2 and SID-IIs in Vehicle Side Impact Tests with the IIHS Barrier

The Insurance Institute for Highway Safety (IIHS) has recently developed and evaluated a new side impact barrier to represent the front profile of pickup trucks and sport utility vehicles for a new consumer information program. In the development of this program, two dummies were considered for assessing driver injury risk in side-struck vehicles: EuroSID-2 (50th percentile male dummy) and SID-IIs (5th percentile female dummy). The purpose of this study was to compare injury responses and kinematics for these two dummies in side impact crash tests. The findings suggest that SID-IIs will be more effective in driving relevant improvements in side impact crash protection.
Technical Paper

Effect of Hybrid III Leg Geometry on Upper Tibia Bending Moments

The knee and ankle joint pivots of the Hybrid III dummy's leg are positioned in approximately the same orientation as the knee and ankle joint rotation centers of a human in a normal driving posture. However, the dummy's leg assembly is not simply a straight member between these two pivots. It is a zigzag-shaped solid link composed of one long straight section in the middle and short angled sections at either end, which form the pivots. The upper and lower tibia load cells are mounted on the straight middle section, making the upper tibia load cell location anterior to the line between the ankle and knee pivots and the lower tibia load cell location slightly posterior to the line between the pivots. Hence, an approximately vertical force on the foot can act along the line behind the upper tibia load cell and in front of the lower tibia load cell, creating bending moments.
Technical Paper

Child Restraint Durability in High-Speed Crashes

The Insurance Institute for Highway Safety installed a variety of infant, toddler, and booster restraints in vehicles subjected to high-speed frontal offset crash tests to assess the effects of severe crashes on the structural integrity of the restraints and their associated hardware (harnesses, buckles, clips, etc.). The child restraints were inspected before and after each test, and all damage was recorded. In some of the tests, forces and accelerations were recorded on the appropriate size child dummy properly secured in the child restraint. After a single severe crash, most restraints had sustained some damage, albeit minimal. Repeated tests indicated that these child restraints could withstand the forces of an additional crash with only minor additional damage. Dummy injury results suggest that current injury risk curves overstate the risk of neck injury to most properly restrained children.
Technical Paper

Analysis of Driver Fatalities in Frontal Crashes of Airbag-Equipped Vehicles in 1990-98 NASS/CDS

This study, which is an extension of an earlier study, examined an additional 64 frontal crashes of airbag-equipped vehicles in the 1997-98 National Automotive Sampling System Crashworthiness Data System (NASS/CDS) in which the driver died. The principal cause of death in each case was determined based on an examination of the publicly available case materials, which primarily consisted of the crash narrative, the injury/source summary, and photographs of the crashed vehicle. Results were consistent with the earlier analyses of the 1990-96 NASS/CDS files. In the combined data set (1990-98), gross deformation of the occupant compartment was the leading cause (42 percent) of driver deaths in these 116 frontal crashes. The force of the deploying airbag (16 percent) and ejection from the vehicle (13 percent) also accounted for significant portions of the driver deaths in these frontal crashes. There continues to be little or no evidence that airbags deploy with too little energy.
Technical Paper

Driver Fatalities in Frontal Crashes of Airbag-Equipped Vehicles: A Review of 1989-96 NASS Cases

Using data from the National Automotive Sampling System/Crashworthiness Data System (NASS/CDS) for1995-96, this study updates previous analyses of driver fatalities in airbag-equipped vehicles in the NASS/CDS database for 1989-93 and 1989-94. A total of 59 cases of frontal crashes of airbag-equipped vehicles with driver fatalities were identified in these 8 years of NASS/CDS data, but in 9 cases the fatalities were not related to the impacts (e.g., fire, medical condition). Vehicle intrusion was the cause of the fatal injuries in 27 cases, and 7drivers died from injuries sustained when they were either partially or totally ejected from their vehicles. There was one case in which the airbag did not deploy, although the crash conditions indicated it should have. One driver died from contact with a nonintruding vehicle surface, and the causes of the fatal injuries in 5 cases were unknown.
Technical Paper

Crash Compatibility Issue in Perspective

Despite extensive media coverage to the contrary, mismatches among cars, utility vehicles, and pickups in crashes is not a big problem from a societal perspective. On the other hand, if you are riding in a small car that is about to be hit by a big utility vehicle, then the problem looms large. Crash compatibility has attracted a lot of attention lately because utility vehicles have become so popular. The concern is that their designs pose a threat to people riding in smaller cars. But the fact is, two-vehicle collisions between cars (including passenger vans) and utility vehicles or pickups account for only about 15 percent of all car occupant deaths. As a result, countermeasures that focus on making utility vehicles and pickups more crash compatible, however appropriate, can have only small effects on crash injuries and fatalities. On the other hand, improvements in crashworthiness not only reduce crash incompatibilities but also protect across a wider spectrum of crashes.
Technical Paper

Factors Contributing to Front-Side Compatibility: a Comparison of Crash Test Results

The occupants of passenger vehicles struck in the side by another vehicle are more likely to be fatally injured than are occupants of the striking vehicle. The risk of fatality in a side-struck car is higher still when the striking vehicle is a pickup or utility vehicle rather than a passenger car of the same mass. This suggests there are other factors inherent to pickup and utility vehicle design in addition to mass that contribute to this increased risk. In this paper, results are presented from a series of six 90-degree, front-to-side crash tests conducted with both vehicles moving. The side-struck vehicle, a Mercury Grand Marquis with a BioSID (biofidelic side impact dummy) in the driver position, was moving at 24 km/h (15 mi/h) in all tests.
Technical Paper

Crash Test Evaluation of Whiplash Injury Risk

A BioRID (biofidelic rear impact dummy) representing a 50th percentile adult male was seated in the front passenger seat of six new vehicle models in a series of low-speed crash tests. The neck injury criterion (NIC) and other dummy responses that may indicate whiplash injury risk were recorded. Both front-into- rear and rear-into-barrier tests with an average velocity change of 11 km/h were conducted. Head restraints were tested in both adjusted (up) and unadjusted (down) positions. Damage to all models was minor, and longitudinal vehicle accelerations were low (less than 7 g). Neck extension angles and bending moments were much less than injury assessment reference values (IARV) (80 degrees and 57 Nm, respectively), indicating low risk of hyperextension injuries. Neck tension and transverse forces also were less than IARVs used to indicate the risk of more serious neck injuries.
Technical Paper

Potential Strategies for Improving Crash Compatibility in the U.S. Vehicle Fleet

After decades of focus on car designs that improve the crash protection of occupants in their own cars, some theorists have refocused their attention on vehicle aggressivity, or more generally, the compatibility of vehicles when they crash with each other. Real-world fatal crash data reveal important issues of compatibility related to the broad mix of types and sizes of vehicles in the fleet. However, these data also show that incompatibility among passenger vehicles has accounted for only a small proportion of crash fatalities on U.S. roads and that modifications of the more aggressive vehicles, though appropriate and necessary, will have relatively small effects. Interventions to curtail the development and sale of the largest and heaviest passenger vehicles would be ineffective.
Technical Paper

Risk of Death Among Child Passengers in Front and Rear Seating Positions

Using 1988-95 data from the Fatality Analysis Reporting System, risk of death was compared among front- and rear-seated passengers ages 12 and younger involved in fatal crashes, controlling for restraint use, passenger airbags, and other variables. Among children sitting in the rear, risk of death was reduced about 35 percent in vehicles without passenger airbags and about 50 percent in vehicles with passenger airbags (difference was not statistically significant). Rear seats were protective for both restrained and unrestrained children. Children were about 10-20 percent less likely to die in rear center than in rear outboard positions.
Technical Paper

Fatalities in Air Bag-Equipped Cars: A Review of 1989-93 NASS Cases

A review of 39 driver fatalities in 1990-93 cars with air bags from the National Accident Sampling System indicated most of these fatalities were due to causes unrelated to frontal air bag performance. Two-thirds occurred in side-impact or rollover crashes, in which air bag effectiveness is limited; of 15 frontal crash fatalities, 6 died of causes unrelated to the frontal impact and 5 in cars with severe intrusion. The remaining four fatalities, three of whom were unbelted, were in moderate to high severity crashes which could have been survivable; however the deploying air bags, instead of protecting, probably contributed to the fatal injuries. A similar review of 12 fatalities of unbelted drivers in cars without air bags revealed 3 could have been prevented by air bags, but 4 were in crashes that could have put them in position to be injured by the air bag.