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Technical Paper

Lumbar Spine Fractures in Undercarriage Impacts: Analysis of 1997-2015 NASS-CDS

2018-04-03
2018-01-0546
Objective: This is a descriptive study of the incidence of spinal injury by crash type using NASS-CDS. It provides an understanding of impacts to the undercarriage of the vehicle and injuries to the lumbar spine by reviewing electronic cases in NASS-CDS to determine crash circumstances for fractures of the lumbar spine with undercarriage impacts. Methods: 1997-2015 NASS-CDS was evaluated for serious injury (MAIS 3 + F) to front-seat occupants by seatbelt use and crash type in 1994+ MY vehicles. Undercarriage impacts were defined by GAD1 = U without a rollover. Serious injury was defined as MAIS 3 + F. Spinal injuries AIS 3+ were separated into cervical, thoracic and lumbar regions. Weighted data was determined using ratio weight. NASS-CDS electronic cases were downloaded from NHTSA with AIS 3+ lumbar spine injuries in undercarriage impacts. Results: There were 2,160 MAIS 3 + F injured occupants in undercarriage impacts. This was 0.23% of all serious injury.
Technical Paper

Abdominal Injuries in Frontal Crashes: Influence of Occupant Age and Seating Position

2018-04-03
2018-01-0535
Objective: This study investigated the incidence of abdominal injuries in frontal crashes by occupant age and seating position. It determined the risk for abdominal injury (AIS 2+) by organ and injury source. Methods: 1997-2015 NASS-CDS was analyzed to estimate the occurrence of abdominal injuries in non-ejected, belted occupants involved in frontal crashes. Vehicles were included with 1997+ model year (MY). The annual incidence and rate for different types of abdominal injury were estimated with standard errors. The sources for abdominal injury were determined. Results: 77.8% of occupants were drivers, 16.7% were right-front passengers and 5.4% were rear passengers. Rear passengers accounted for 77.1% of 8-11 year old (yo) and 17.2% of 12-17 yo group. The risk for moderate abdominal injury (MAIS 2 + abdo) was 0.30% ± 0.053% in drivers, 0.32% ± 0.086% in right-front passengers and 0.38% ± 0.063% in rear occupants.
Journal Article

Basilar Skull Fractures by Crash Type and Injury Source

2011-04-12
2011-01-1126
Purpose: This study investigates NASS-CDS data on basilar skull fractures by crash type and injury source for various crash scenarios to understand the injury risks, injury mechanisms and contact sources. Methods: 1993-2008 NASS-CDS data was used to study basilar skull fractures in adult front occupants by crash type and injury source. Injury risks were determined using weighted data for occupants with known injury status in 1994+ model year vehicles. In-depth analysis was made of far-side occupants in side impacts and rear crashes using the NASS electronic cases. Results: Basilar skull fractures occur in 0.507 ± 0.059% of rollovers and 0.255 ± 0.025% of side impacts. The lowest risk is in rear impacts at 0.015 ± 0.007%. The most common contact source is the roof, side rails and header (39.0%) in rollovers, the B-pillar (25.8%) in side impacts and head restraint (55.3%) in rear crashes.
Technical Paper

Fracture-Dislocation of the Thoracic Spine in Extension by Upright Seats in Severe Rear Crashes

2011-04-12
2011-01-0274
Purpose: This study presents cases of fracture-dislocation of the thoracic spine in extension during severe rear impacts. The mechanism of injury was investigated. Methods: Four crashes were investigated where a lap-shoulder-belted, front-seat occupant experienced fracture-dislocation of the thoracic spine and paraplegia in a severe rear impact. Police, investigator and medical records were reviewed, the vehicle was inspected and the seat detrimmed. Vehicle dynamics, occupant kinematics and injury mechanisms were determined in this case study. Results: Each case involved a lap-shoulder-belted occupant in a high retention seat with ≻1,700 Nm moment or ≻5.5 kN strength for rearward loading. The crashes were offset rear impacts with 40-56 km/h delta V involving under-ride or override by the impacting vehicle and yaw of the struck vehicle. In each case, the occupant's pelvis was restrained on the seat by the open perimeter frame of the seatback and lap belt.
Technical Paper

Front-Seat Occupant Injuries in Rear Impacts: Analysis of the Seatback Incline Variable in NASS-CDS

2009-04-20
2009-01-1200
Objective: This study addresses severe injury risks in rear impacts for front-outboard occupants using the seatback incline variable in NASS-CDS. Methods: Severe injury risk (MAIS 4+F) was determined for front-seat occupants in rear impacts involving passenger cars from 1995–2006 NASS-CDS data. The risk of severe injury to front-seat occupants was determined as a function of the rotated position of the seatback and crash severity in three delta V ranges: <20, 20–30, >30 mph. The data was also analyzed for newer model vehicles (≥1997 MY) to assess changes with newer seats and head restraints. The effects of seatbelt use, occupant age and BMI (Body Mass Index) were also examined. Individual NASS-CDS electronic cases were also reviewed with MAIS 4+F injury. There were 25 injured occupants in rotated seats and 46 in non-rotated seats. Results: Severe injury risk for front-seat occupants in rear impacts is lower with a rotated seatback in the most severe rear crashes.
Journal Article

Front Seat Performance in Rear Impacts: Effect on 1st and 2nd Row Occupant Injury

2009-04-20
2009-01-0252
Purpose: This study analyzes the effect of front seat performance on occupant injury in rear crashes where there is a 2nd row passenger seated behind the front occupant. Methods: The study was carried out for rear impact crashes in the 1991–2006 NASS-CDS. Only cases where there was a 2nd row occupant seated behind an occupied front seat were chosen. Serious injury (MAIS 3+F) was determined for the front and 2nd row occupants. The performance of the front seat was determined using eight NASS-CDS investigator categories, including no failure, seat failure of the adjuster, seatback or track-anchor and seat deformation by the occupant or intrusion. The rear crashes were subdivided into four severities (<15, 15–25, 25–45 and >45 mph). The risk for serious injury was determined for each category of seat performance. Next, individual cases were reviewed from the online NASS electronic files to better understand the determination of seat performance by the NASS-CDS investigators.
Journal Article

Jaw Loading Response of Current ATDs

2009-04-20
2009-01-0388
Biomechanical surrogates are used in various forms to study head impact response in automotive applications and for assessing helmet performance. Surrogate headforms include those from the National Operating Committee on Standards for Athletic Equipment (NOCSAE) and the many variants of the Hybrid III. However, the response of these surrogates to loading at the chin and how that response may affect the loads transferred from the jaw to the rest of the head are unknown. To address part of that question, the current study compares the chin impact response performance of select human surrogates to that of the cadaver. A selection of Hybrid III and NOCSAE based surrogates with fixed and articulating jaws were tested under drop mass impact conditions that were used to describe post mortem human subject (PMHS) response to impacts at the chin (Craig et al., 2008). Results were compared to the PMHS response with cumulative variance technique (Rhule et al., 2002).
Journal Article

Vehicle and Occupant Responses in a Friction Trip Rollover Test

2009-04-20
2009-01-0830
Objective: A friction rollover test was conducted as part of a rollover sensing project. This study evaluates vehicle and occupant responses in the test. Methods: A flat dolly carried a Saab 9-3 sedan laterally, passenger-side leading to a release point at 42 km/h (26 mph) onto a high-friction surface. The vehicle was equipped with roll, pitch and yaw gyros near the center of gravity. Accelerometers were placed at the vehicle center tunnel, A-pillar near the roof, B-pillar near the sill, suspension sub-frame and wheels. Five off-board and two on-board cameras recorded kinematics. Hybrid III dummies were instrumented for head and chest acceleration and upper neck force and moment. Belt loads were measured. Results: The vehicle release caused the tires and then wheel rims to skid on the high-friction surface. The trip involved roll angular velocities >300 deg/s at 0.5 s and a far-side impact on the driver’s side roof at 0.94 s. The driver was inverted in the far-side, ground impact.
Technical Paper

Fatalities by Seating Position and Principal Direction of Force (PDOF) for 1st, 2nd and 3rd Row Occupants

2008-05-12
2008-01-1850
Purpose: A better understanding of rear occupant fatality risks is needed to guide the development of safety improvements for 2nd and 3rd row occupants. This study investigates fatal accidents of 1st, 2nd and 3rd row occupants by principal direction of force (PDOF), irrespective of restraint use. It determined the number of fatalities, exposure and fatality risk. Methods: 1996-2005 FARS was analyzed for occupant fatalities by seating position (1st, 2nd and 3rd row) and principal direction of force (1-12 o'clock PDOF, rollover and other/unknown). Light vehicles were included with model year 1990+. 1996-2005 NASS-CDS was similarly analyzed for occupant exposure. Fatality risk was defined as the number of fatalities in FARS for a given category divided by the exposure from NASS-CDS. Results: Ten percent (9.6%) of fatalities were to 2nd row occupants in FARS. About 2,080 deaths occur to 2nd row occupants annually. 38.4% died in rollovers and 26.8% in frontal crashes.
Technical Paper

Field Accident Data Analysis of 2nd Row Children and Individual Case Reviews

2008-05-12
2008-01-1851
Child safety is an important issue. The objective of this study was to analyze field accident data for 0-7 year old children in the 2nd row by vehicle and crash type, irrespective of restraint use. The data was obtained from NASS-CDS for calendar years 1991-2005. Accidents were selected based on 2nd row occupancy in towaway light vehicles with model year 1990 or newer. Side impacts caused 30.9% of serious-to-fatal injury (MAIS 3+F) to 2nd row children followed by frontal impacts (29.8%), rollovers (24.4%) and rear crashes (15.0%). The highest risk for MAIS 3+F was in rollovers (2.8 ± 0.7%) followed by rear (1.4 ± 0.4%), side (1.0 ± 0.2%) and frontal (0.46 ± 0.10%) crashes. The differences are statistically significant (p <0.01). Individual rear and frontal impact cases were also reviewed to better understand injury mechanisms of children in the 2nd row. The cases were obtained from the 1997-2005 NASS-CDS electronic database.
Technical Paper

Crash Injury Risks for Obese Occupants

2008-04-14
2008-01-0528
Obesity rates are reaching an epidemic worldwide. In the US, nearly 40 million people are obese. The automotive safety community is starting to question the impact of obesity on occupant protection. This study investigates fatality and serious injury risks for front-seat occupants by Body Mass Index (BMI). NASS-CDS data was analyzed for calendar years 1993-2004. Occupant exposure and injury was divided in seven BMI categories with obese defined as those with BMI ≥ 30 kg/m2. Injuries were studied for drivers and right-front passengers and included analysis of lap-shoulder belted and unbelted occupants. The results show that obese occupants have a higher fatality risk compared to normal BMI occupants; morbidly obese occupants (BMI ≥ 40 kg/m2) have 2.25 times higher fatality risk (1.15% v 0.51%). The fatality risk for belted obese drivers was 0.29%, which was 6.7 times lower than the 1.94% for those unbelted. These rates are similar to other BMI occupants.
Technical Paper

Occupant Responses in High-Speed Rear Crashes: Analysis of Government-Sponsored Tests

2008-04-14
2008-01-0188
The objective of this study was to analyze available anthropomorphic test device (ATD) responses from FMVSS 301-type rear impact tests. Rear impact test data was obtained from NHTSA and consisted of dummy responses, test observations, photos and videos. The data was organized in four test series: 1) NCAP series of 30 New Car Assessment Program tests carried out at 35 mph with 1979-1980 model year vehicles, 2) Mobility series of 14 FMVSS 301 tests carried out at 30 mph with 1993 model year vehicles, 3) 301 MY 95+ series of 79 FMVSS 301 tests carried out at 30 mph with 1995-2005 model year vehicles and 4) ODB series of 17 Offset Deformable Barrier tests carried out at 50 mph with a 70% overlap using 1996-1999 model year vehicles. The results indicate very good occupant performance in yielding seats in the NCAP, Mobility and 301 MY 95+ test series.
Technical Paper

Serious Injury in Very-Low and Very-High Speed Rear Impacts

2008-04-14
2008-01-1485
The objective of this study was to analyze rear crashes for the risk of serious injury (AIS 3+) by delta V. Rear impacts were analyzed for occupants sitting in front seats of light vehicles. Data was obtained from NASS-CDS for calendar years 1991-2004. Tow-away crashes with ≤15 mph rear delta V account for 67% of rear impacts and 15% of serious injury. Even for crashes <30 mph delta V, the risk for serious injury is only 0.24% (less than 1 per 420 exposed occupants). Risks increase for higher delta Vs. Individual cases in the 1997-2004 NASS-CDS electronic database were reviewed for serious injury in crashes with ≤15 mph delta V and ≥35 mph for light vehicles with calendar year >1996 to better understand injury mechanisms. Nine cases were available where a front-seat occupant was seriously injured in ≤15 mph rear delta V impact. Most cases involved older occupants, some of whom had stenosis of the cervical spine.
Technical Paper

Stiff versus Yielding Seats: Analysis of Matched Rear Impact Tests

2007-04-16
2007-01-0708
The objective of this study was to analyze available anthropomorphic test device (ATD) responses from KARCO rear impact tests and to evaluate an injury predictive model based on crash severity and occupant weight presented by Saczalski et al. (2004). The KARCO tests were carried out with various seat designs. Biomechanical responses were evaluated in speed ranges of 7-12, 13-17, 18-23 and 24-34 mph. For this analysis, all tests with matching yielding and stiff seats and matching occupant size and weight were analyzed for cases without 2nd row occupant interaction. Overall, the test data shows that conventional yielding seats provide a high degree of safety for small to large adult occupants in rear crashes; this data is also consistent with good field performance as found in NASS-CDS. Saczalski et al.'s (2004) predictive model of occupant injury is not correct as there are numerous cases from NASS-CDS that show no or minor injury in the region where serious injury is predicted.
Book

Occupant and Vehicle Responses in Rollovers

2004-03-08
During the past decade, there has been a steady increase in studies addressing rollover crashes and injuries. Though rollovers are not the most frequent crash type, they are significant with respect to serious injury and interest in rollovers has grown with the introduction of SUVs, vans, and light trucks. A review of Occupant and Vehicle Responses in Rollovers examines relevant conditions for field roll overs, vehicle responses, and occupant kinetics in the vehicle. This book edited by Dr. David C. Viano and Dr. Chantal S. Parenteau includes 62 technical documents covering 15 years of rollover crash safety, including field crash statistics, pre- and rollover dynamics, test procedures and dummy responses.
Technical Paper

Bounce-Overs: Fixed Object Impacts Followed by Rollovers

2004-03-08
2004-01-0334
In this study, U.S. crash data was analyzed to better understand bounce-over rollovers. Crash data was reviewed to evaluate the distribution of bounce-over crashes and injuries, initiation objects and impact locations. In passenger cars, bounce-over crashes account for 8.4% of rollovers but involve 36.2% of the seriously injured belted drivers. Most bounce-overs are initiated by contact with narrow objects such as a pole, tree or barrier, or large objects such as a ditch or embankment. Contact often occurs in the front of the vehicle. After contact, the vehicle yaws and rolls, and serious injuries are often sustained to the head. Based on field data, a laboratory test was developed to simulate a narrow object bounce-over. The test consists of towing a vehicle laterally on a fixture towards a stationary, angled barrier resting in gravel. The moving fixture is decelerated and the vehicle is released. The vehicle front impacts the edge of the barrier, simulating a narrow object impact.
Technical Paper

Rollover Crash Sensing and Safety Overview

2004-03-08
2004-01-0342
This paper provides an overview of rollover crash safety, including field crash statistics, pre- and rollover dynamics, test procedures and dummy responses as well as a bibliography of pertinent literature. Based on the 2001 Traffic Safety Facts published by NHTSA, rollovers account for 10.5% of the first harmful events in fatal crashes; but, 19.5% of vehicles in fatal crashes had a rollover in the impact sequence. Based on an analysis of the 1993-2001 NASS for non-ejected occupants, 10.5% of occupants are exposed to rollovers, but these occupants experience a high proportion of AIS 3-6 injury (16.1% for belted and 23.9% for unbelted occupants). The head and thorax are the most seriously injured body regions in rollovers. This paper also describes a research program aimed at defining rollover sensing requirements to activate belt pretensioners, roof-rail airbags and convertible pop-up rollbars.
Book

The Debate Between Stiff and Yielding Seats

2004-01-16
In 1967, Derwyn M. Severy and his colleagues published several SAE papers that demonstrated improvements in occupant retention with rigid (stiff) seats, sparking a debate that lasted for nearly four decades. The Debate Between Stiff and Yielding Seats presents an interesting and informative history of this debate, delving into the many questions and answers that continue to surround each of these seat types. The Debate Between Stiff and Yielding Seats begins with new material from editor David C. Viano, explaining the key factors that allowed the debate to be resolved. The publication then analyzes the effects of stiff and yielding seats on various crash scenarios, followed by an exploration of high retention seats. Patent information, new studies, and historical information are also included, making this comprehensive collection an essential resource for any safety professional's library.
Technical Paper

Effectiveness of High-Retention Seats in Preventing Fatality: Initial Results and Trends

2003-03-03
2003-01-1351
In 1995, new seat specifications were adopted by GM to provide high retention and improve occupant safety in rear crashes. With more than five years of phase-in of high retention (HR) seats, an analysis of FARS was undertaken to determine the initial field performance of HR seats in preventing fatalities. The 1991-2000 FARS was sorted for fatal rear-impacted vehicles. Using a VIN decoder, GM vehicles with HR front seats were sorted from those with baseline (pre-HR) seats. The fatal rear-impacted vehicle crashes were subdivided into several groups for analysis: 1) single-vehicle rear impacts, 2) two-vehicle rear crashes involving light striking vehicles, and 3) two-vehicle crashes involving heavy trucks and tractor-trailers, and multi-vehicle (3+) rear crashes.
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