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Blunt impacts to the back of the torso can occur in vehicle crashes due to interaction with unrestrained occupants, or cargo in frontal crashes, or intrusion in rear crashes, for example. Six pendulum tests were conducted on the back of an instrumented 50th percentile male Hybrid III ATD (Anthropomorphic Test Device) to determine kinematic and biomechanical responses. The impact locations were centered with the top of a 15-cm diameter impactor at the T1 or at T6 level of the thoracic spine. The impact speed varied from 16 to 24 km/h. Two 24 km/h tests were conducted at the T1 level and showed repeatability of setup and ATD responses. The 16 and 24 km/h tests at T1 and T6 were compared. Results indicated greater head rotation, neck extension moments and neck shear forces at T1 level impacts. For example, lower neck extension was 2.6 times and 3.8 times greater at T1 versus T6 impacts at 16 and 24 km/h, respectively.

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.

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.

This study analyzed FMVSS 301 rear impact tests with an instrumented rear-seat dummy. NHTSA conducted 15 FMVSS 301 rear crash tests with an instrumented and belted 50th Hybrid III dummy in the rear seat. In series 1, there were three repeat tests with the Jeep Liberty and two others, but no onboard camera view. In series 2, there were 8 tests with 2003-2005 MY (model year) vehicles that had rear head restraints. In series 3, there were two tests with 2004-2005 MY vehicles that did not have rear head restraints. There was an onboard camera view of the rear occupant in series 2 and 3. The dummy responses were evaluated and compared to relevant IARVs (injury assessment reference values). Based on the HRMD, the average height of the rear head restraints was 80.4 ± 3.4 cm (31.6″ ± 1.3″) above the H-point. In series 1, the delta V was 24.4 ± 2.0 km/h (15.2 ± 1.3 mph).

Objective: This study involved a number of different tests addressing theories for recliner and track release of front seats in rear impacts. It addresses the validity of the theories. Method: Several separate test series were conducted to address claims made about recliner and track release of front seats in rear impacts. The following theories were evaluated to see the validity of the issues: 1 Recliner teeth slipping with minimal damage to the teeth 2 Recliner teeth bypass by disengaging and re-engaging under load without damaging the teeth 3 Recliner shaft bending and torque releasing the recliners 4 Track release by heel loading 5 Track release with occupant load on the seat 6 Recliner handle rotation causing recliner release 7 Double pull body block tests Results: Many of the theories were found to be uncorroborated once actual test data was available to judge the merits of the issue raised. The laboratory tests were set-up to specifically address particular issues.

Objective: This study analyzed available rear impact sled tests with Starcraft-type seats that use a diagonal belt behind the seatback. The study focused on neck responses for out-of-position (OOP) and in-position seated dummies. Methods: Thirteen rear sled tests were identified with out-of-position and in-position 5 th , 50 th and 95 th Hybrid III dummies in up to 47.6 mph rear delta Vs involving Starcraft-type seats. The tests were conducted at Ford, Exponent and CSE. Seven KARCO rear sled tests were found with in-position 5 th and 50 th Hybrid III dummies in 21.1-29.5 mph rear delta Vs involving Starcraft-type seats. In all of the in-position and one of the out-of-position series, comparable tests were run with production seats. Biomechanical responses of the dummies and test videos were analyzed.

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.

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.

Objective: This study analyzes rear sled tests with a 95th% male and 5th% female Hybrid III dummy in various seating positions on ABTS (All Belt to Seat) seats in severe rear impact tests. Dummy interactions with the deforming seatback and upper body extension around the seat frame are considered. Methods: The 1st series involved an open sled fixture with a Sebring ABTS seat at 30 mph rear delta V. A 95th% Hybrid III dummy was placed in four different seating positions: 1) normal, 2) leaning inboard, 3) leaning forward and inboard, and 4) leaning forward and outboard. The 2nd series used a 5th% female Hybrid III dummy in a Grand Voyager body buck at 25 mph rear delta V. The dummy was leaned forward and inboard on a LeSabre ABTS or Voyager seat. The 3rd series used a 5th% female Hybrid III dummy in an Explorer body buck at 26 mph rear delta V. The dummy was leaned forward and inboard on a Sebring ABTS or Explorer seat.

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.

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.

Motorized shoulder belt tensioning is a new automotive seatbelt technology which has shown promise to reduce automotive crash injuries. The current study was conducted to determine if the Hybrid III family of dummies is an appropriate biofidelic surrogate for studying motorized shoulder belt tensioning. The objective was to measure torso retraction time, torso position, torso velocity, internal resistive moment, changes in torso curvature and the center of rotation of torso extension during seatbelt tensioning for the Hybrid III family. A previous study developed a protocol and test fixture to measure the biomechanics of volunteers subject to quasi-static loading by a motorized shoulder belt tensioner. A fixture supported the occupant leaning forward and applied shoulder belt tension. Kinematics were quantified by analyzing the motion of reflective markers on the dummy using an eight camera digital video system. A three axis load cell measured internal resistance to extension.

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.

Motorized shoulder belt tensioning is an occupant protection technology that has promise to reduce automotive crash injuries. The objective of this study was to model the response of a diverse forward-leaning occupant population (6-year-old child, 5th female, 50th male, 95th male) to shoulder belt tensioning during straight line pre-crash braking. The lumped mass model was based on experimental volunteer data for motorized shoulder belt tensioning gathered in a previous quasistatic study. The three dimensional model incorporated the biomechanical properties of the occupant populations, a motorized shoulder belt tensioner (DC motor and controller) and shoulder belt webbing models. Model validation was achieved against the volunteer experiments for angular torso position, torso velocity and shoulder belt moment applied to the torso.

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.

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.

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.

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.

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.

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.