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The average body weight of the US population has increased over time. This study investigates the effect of increasing weight on seat and occupant responses in 15-18 km/h and 42 km/h rear sled tests. The effect of initial occupant posture is also discussed. Seven tests were conducted with lap-shoulder belted ATDs (anthropometric test device) placed on older and modern driver seats. Four tests were conducted with a 50th percentile male Hybrid III, two with 95th percentile male Hybrid III and one with a BioRID. The ATDs were ballasted to represent a Class I or II obese occupant in three tests. The tests were matched by seat model and sled velocity. The effect of occupant weight was assessed in three matches. The results indicated an increase in seatback deflection with increasing occupant weight.

Rollovers are an important vehicle safety issue. Various technologies have been developed to help prevent rollovers from occurring, but the evaluation of rollover resistance typically involves vehicle-handling tests that are conducted on flat road surfaces with a uniform or split coefficient of friction. The purpose of this study is to determine the precipitating events leading to rollovers by analyzing real-world rollover crashes. This is a first step in identifying and developing vehicle tests that are representative of the principal driving scenarios leading to rollovers. The sequence of events leading to rollovers was determined from 63 in-depth investigated cases in the NASS-CDS database from 1995-1999. The sequence was evaluated by vehicle maneuvers, vehicle stability, surface type, road and shoulder transition condition, posted and estimated speeds, vehicle type and driver injury severity.

Since more occupants are using rear seats of vehicles, a better understanding of priorities for rear occupant protection is needed as future safety initiatives are considered. A two-part study was conducted on occupant injuries in rear seating positions. In Part I, adult and teenage occupants ≥13 years of age are investigated. In Part II, children aged 4-12 years old and toddlers and infants aged 0-3 are studied separately because of the use of infant and child seats and boosters involve different injury mechanisms and tolerances. The objectives of this study on adult and teenager, rear-seated occupants (≥13 years old) are to: 1) review accident data, 2) identify the distribution of rear occupants, and 3) analyze injury risks in various crash modes, including rollovers, frontal, side and rear impacts. Three databases were investigated: NASS-CDS, GES and FARS.

Child safety continues to be an important issue in automotive safety for many reasons, including reported cases of serious injury from airbag deployments. As a result of extensive public education campaigns, most children are now placed in rear seats of vehicles. Accordingly, a more precise understanding of rear-seat occupant protection is developing as the second and third rows have become the primary seating area for children in SUVs, vans and passenger cars. The objective of this study was to review field crash and injury data from rear seats, identify the distribution of children and infants in rear seats, and analyze injury risks in various crash modes. The database used was the 1991-1999 NASS-CDS. When looking at crash configurations for 1st and 2nd row children, rollover crashes involved the highest incidence of MAIS 3+ injury, followed by frontal and side impacts. Lap-shoulder belt usage was similar for 1st and 2nd row children.

This study evaluates the comfort benefits of adjustable pedals by determining their effect on the distance between the occupant and steering wheel, occupant posture and foot kinematics. For the study, 20 volunteers were tested in a small and large vehicle equipped with adjustable pedals. Twenty volunteers were tested in a small and large vehicle at 3 pedal positions: normal, comfortable and maximum tolerable. In the small car, the decrease in ankle-to-steering wheel distance between the normal and comfortable position was higher in the short-statured group than the medium group. The mean change in chest-to-steering wheel distance was about 50 mm in the medium and in the order of 40 mm in the short group. The seatback angle increased by 2° in the medium group and decreased by 3° in the short group. In the large car, the decrease in ankle-to-steering wheel distance between comfortable and the normal position was about 70 mm in the short-statured and medium group.

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).

Occupant protection in rear crashes is complex. While seatbelts and head restraints are effective in rear impacts, seatbacks offer the primary restraint component to front-seat occupants in rear impacts. Seatback deflection due to occupant loading can occur in a previous rear crash and/or in multiple-rear event crashes. Seatback deflection will in-turn affect the plastic seatback deformation and energy absorption capabilities of the seat. This study was conducted to provide information on seatback deflection and seat energy consumption in low and high-speed rear impacts. The results can be used to examine seatback deflection and energy consumed in a previous rear impact, or in collisions with multiple rear impacts. Prior seatback deflection and energy absorption can affect the total remaining energy absorption and seat performance for a subsequent rear impact.

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.

The purpose of this paper is to investigate occupant injuries which may be sustained during a single-event crash with known roll mechanism. The data was obtained from the weighted National Automotive Sampling System/ Crashworthiness Data System (NASS-CDS) for calendar years 1992 to 1996. The effect of number of rollover turns, roll direction, ejection and belt usage on driver injury responses was analyzed in single-event trip-overs. Trip-overs were chosen for the analysis because they account for over 50% of rollover crashes. The number of rollovers was divided in 3 categories: ¼ to ½ turn, ¾ to 1 turn and above 1 turn. Roll direction was either roll-left or a rollright along the longitudinal axis of the vehicle. Roll-left represents a roll with the driver side leading, while a roll right is with the right front passenger side leading. In the database used in this study, there were three times more belted drivers than unbelted.

Seats have become stronger over the past two decades and remain more upright in rear impacts. While head restraints are higher and more forward providing support for the head and neck, serious-to-fatal injuries to the thoracic and cervical spine have been seen in occupants with spinal disorders, such as DISH (diffuse idiopathic skeletal hyperostosis), ankylosis, spondylosis and/or osteophytes that ossify the joints in the spine. This case study addresses the influence of spinal disorders on fracture-dislocation and spinal cord injury in rear impacts with relatively upright seats. Nineteen field accidents were investigated where serious-to-fatal injuries of the thoracic and cervical spine occurred with the seat remaining upright or slightly reclined. The occupants were lap-shoulder belted, some with belt pretensioning and cinching latch plate.

Objective: Sled test video and data were independently analyzed to assess the validity of statements and conclusions reported in Bidez et al. SAE paper 2005-01-1708 [7]. Method: An independent review and analysis of the test data and video was conducted for 9 sled tests at 35 km/h (21.5 mph). The 5th female Hybrid III was lap-shoulder belted in the 2nd or 3rd row seat of a SUV buck. For one series, the angle was varied from 0, 15, 30, 45 and 60 deg PDOF. The second series involved shoulder belt pretensioning and other belt modifications. Results: Bidez et al. [7] claimed “The lap belts moved up and over the pelvis of the small female dummy for all impact angles tested.” We found that there was no submarining in any of the tests with the production lap-shoulder belts. Bidez et al. [7] claimed “H3-5F dummies began to roll out of their shoulder belt at… 30 degrees. Complete loss of torso support was seen at 45 degrees without significant kinetic energy dissipation.”

The risk for severe injury (MAIS 4+F) was determined by crash type, seatbelt use and crash severity (delta V) using 22 years of NASS-CDS from 1994-2015 with all light vehicles and occupants 15+ years old. There were 9 increments of delta V from <16-72+ km/h (<10-45+ mph). Crashes were grouped by the location of damage to the front, near-side, far-side and rear. Injury risk was calculated by dividing the number of severely injured (MAIS 4+F) by the number of exposure (MAIS 0+F) occupants using weighted data. Standard errors were determined. The data and plots provide a national estimate of injury by delta V in front, near-side, far-side and rear impacts based on the multi-year field data in NASS-CDS.

Interest in rear-seat occupant safety has increased in recent years. Information relevant to rear-seat occupant interior space and kinematics are needed to evaluate injury risks in real-world accidents. This study was conducted to first assess the effect of size and restraint conditions, including belt misuse, on second-row occupant kinematics and to then document key clearance measurements for an Anthropomorphic Test Device (ATD) seated in the second row in modern vehicles from model years 2015-2020. Twenty-two tests were performed with non-instrumented ATDs; three with a 5th percentile female Hybrid III, 10 tests with a 10-year-old Hybrid III, and 9 tests with a 6-year-old Hybrid III. Test conditions included two sled bucks (mid-size car and sport utility vehicle (SUV)), two test speeds (56 and 64 km/h), and various restraint configurations (properly restrained and improperly restrained configurations). Head and knee trajectories were assessed.

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.

Crash safety researchers have an increased concern regarding the decreased thoracic deflection and the contributing injury causation factors among the elderly population. Sternum fractures are categorized as moderate severity injuries, but can have long term effects depending on the fragility and frailty of the occupant. Current research has provided detail on rib morphology, but very little information on sternum morphology, sternum fracture locations, and mechanisms of injury. The objective of this study is two-fold (1) quantify sternum morphology and (2) document sternum fracture locations using computed tomography (CT) scans and crash data. Thoracic CT scans from the University of Michigan Hospital database were used to measure thoracic depth, manubriosternal joint, sternum thickness and bone density. The sternum fracture locations and descriptions were extracted from 63 International Center for Automotive Medicine (ICAM) crash cases, of which 22 cases had corresponding CT scans.

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.

This study was conducted to assess the effects of differing rear impact pulse characteristics on restraint performance, front-seat occupant kinematics, biomechanical responses, and seat yielding. Five rear sled tests were conducted at 40.2 km/h using a modern seat. The sled buck was representative of a generic sport utility vehicle. A 50th percentile Hybrid III ATD was used. The peak accelerations, acceleration profiles and durations were varied. Three of the pulses were selected based on published information and two were modeled to assess the effects of peak acceleration occurring early and later within the pulse duration using a front and rear biased trapezoidal characteristic shape. The seatback angle at maximum rearward deformation varied from 46 to 67 degrees. It was lowest in Pulse 1 which simulates an 80 km/h car-to-car rear impact.

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.

This study assesses vehicle and occupant responses in six vehicle-to-vehicle high-speed rear impact crash tests conducted at the Exponent Test and Engineering Center. The struck vehicle delta Vs ranged from 32 to 76 km/h and the vehicle centerline offsets varied from 5.7 to 114 cm. Five of the six tests were conducted with Hybrid III ATDs (Anthropometric Test Device) with two tests using the 50th male belted in the driver seat, one test with an unbelted 50th male in the driver seat, one test with a 95th male belted in the driver seat, and one with the 5th female lap belted in the left rear seat. All tests included vehicle instrumentation and three tests included ATD instrumentation. The ATD responses were analyzed and compared to corresponding IARVs (injury assessment reference values). Ground-based and onboard vehicle videos were synchronized with the vehicle kinematic data and biomechanical responses.

Seat strength has increased over the past four decades which includes a transition to dual recliners. There are seat collision performance issues with stiff ABTS and very strong seats in rear impacts with different occupant sizes, seating positions and physical conditions. In this study, eight rear sled tests were conducted in four series: 1) ABTS in a 56 km/h (35 mph) test with a 50th Hybrid III ATD at MGA, 2) dual-recliner ABTS and F-150 in a 56 km/h (35 mph) test with a 5th female Hybrid III ATD at Ford, 3) dual-recliner ABTS in a 48 km/h (30 mph) test with a 95th Hybrid III ATD leaning inboard at CAPE and 4) dual-recliner ABTS and Escape in 40 km/h (25 mph) in-position and out-of-position tests with a 50th Hybrid III ATD at Ford. The sled tests showed that single-recliner ABTS seats twist in severe rear impacts with the pivot side deformed more rearward than the stanchion side.