Transport Research International Documentation (TRID)

A Crash-Energy Distribution Technique for Seats to Improve Neck Protection in Rear-End Impacts

Mon, 13 Jul 2026 10:46:17 GMT

In this study, a state-of-the-art whiplash-mitigating passive seat is retrofitted with a pro-active head-restraint, an auxiliary damper at the recliner and a firmer layer of seat back suspension and foam in the seat back structure so as to provide improved neck protection for rear-end impacts having delta-V's between 13 km/h and 35 km/h. The retrofitted seat proposed in this study is designed by using a biofidelic occupant model which is a 50th percentile male. Virtual sled tests are performed in accordance with the EuroNCAP dynamic whiplash assessment protocol. The crash energy to be absorbed by the seat components are distributed to provide balanced protection for all severities. The proposed forward-facing retrofitted seat earns maximum points from the EuroNCAP whiplash rating even for a rear-end impact having 35 km/h of delta-V. This paper draws attention to designing seats that can withstand very high severity rear-end impacts and provide sufficient neck protection to limit whiplash associated disorders considerably.

Numerical Investigation of the Effects of Pre-Crash Braking on Occupant Neck Whiplash Injury

Mon, 26 Jan 2026 14:44:19 GMT

Among vehicle collisions, rear-end collision is the main injury source of neck whiplash injury. With the increasing prevalence of autonomous emergency braking systems in new vehicles, occupant postures during rear-end collisions have become more diverse. Thus, it is imperative to study the occupant kinematics of out-of-position (OOP) passengers during rear-end collisions. This paper integrated both volunteer tests and computer-aided engineering methods to analyse the occupant kinematics and main whiplash injury indexes for OOP passengers among the braking-induced rear-end collision scenarios. The research results indicated that a larger velocity change of braking resulted in greater occupant head and chest displacements. In rear-end collisions of the same impact severity, the main injury indexes of the OOP occupants were worse when compared with those of the standard seated occupants, among which the lower neck Fz forces were 624% and 411% of the base model, respectively. Furthermore, the relative displacement increased both head and chest peak accelerations. These research results are beneficial for the development of active restraint systems, as well as the update of the whiplash test protocol.

TMA Truck Safety

Mon, 18 Aug 2025 08:50:41 GMT

This study evaluates the effectiveness of in-vehicle safety countermeasures in reducing injury risk for TMA (Truck-Mounted Attenuator) truck occupants during collisions. With increasing incidents involving TMAs in work zones, understanding the protective impact of advanced safety features has become crucial. A review of historical TMA crash reports revealed that rear-end collisions are the primary issue, with whiplash injuries being the most common type of injury among drivers. Current in-vehicle safety countermeasures were examined, including active headrests, reactive seatbacks, and anti-whiplash systems, which were tested across six simulated collision scenarios incorporating varying vehicle weights, speeds, and impact angles. Using a biomechanical simulation model and telematic data, results indicated that active headrests, particularly with 40 mm travel level, consistently reduced injury criteria values (NIC, Nij, Nkm), effectively lowering head and neck injury risks in both straight and angled collisions. In contrast, the reactive seatback and anti-whiplash systems demonstrated mixed efficacy, performing well in low-impact conditions but poorly in high-impact scenarios. Limited high-impact telematic data, particularly with 80,000-pound vehicles, highlight the need for further validation for high-impact collision scenarios. Findings suggest that integrating advanced head restraint systems could significantly enhance TMA truck driver safety.

Relationship of Whiplash Injury Metrics and Crash Pulse Severity to Injury Claim Rates

Mon, 18 Mar 2024 17:19:56 GMT

This research investigated rear-impact sled tests, three different crash pulses, correlation with injury claim rates, and various seat designs. Seats from midsize automobiles and midsize sport utility vehicles (SUVs) were tested with various acceleration pulses, including Insurance Institute for Highway Safety and European New Car Assessment Programme (Euro NCAP) medium 16 km/h, Japan NCAP 20 km/h and Euro NCAP high 24 km/h. Whiplash injury metrics were calculated using data from sensors in the crash dummies neck, head, vertebrae, and pelvis. Insurance data was analyzed to calculate the rate of injury claims filed with rear-impact property damage liability (PDL) claims. The best predictors of injury claim rate were T1 X-acceleration from the 24-km/h pulse, Max NKM (neck injury criteria predictor), and head contact time (HCT).

Whiplash injuries in low-speed frontal impacts : Frontal validation of VIVA+ head-neck

Tue, 27 Feb 2024 14:26:16 GMT

Whiplash associated disorders are injuries occurring during low-severity impacts and constitute the majority of the cervical spine injuries leading to long-term disabilities. The focus of research and development has during the past decades primarily been towards the rear-end impacts, motivated by the large injury frequencies and risks compared to the other impact directions. Consequently, injury preventing measures have resulted in whiplash injury reductions, mainly concentrated to rear-end impacts. However, initial whiplash symptoms have a 20–30% distribution to frontal collisions, a considerable magnitude that motivates for a need to address whiplash that occurs in frontal impacts as well. Additionally, the preventing measures implemented for rear-end collisions have had 65% higher effect for males compared to females, even though females are proven to have a higher risk to sustain the injury. The VIVA+ 50M and VIVA+ 50F are the first open-source human body models (HBMs) representing both average male population and average female population, respectively. These models are newly developed, and the head-neck kinematics have therefore not yet been validated for frontal low-speed impacts. The aim of this study was to address the need of increasing the knowledge regarding both females’ and males’ risk of whiplash injuries in frontal collisions by presenting a scientific literature overview, and the objective was to validate the kinematic responses of an isolated head-neck submodel VIVA+ 50M for frontal impacts and compare to the VIVA+ 50F responses.

Occupant neck muscle modelling in rear-end crashes

Tue, 27 Feb 2024 14:25:17 GMT

The ultimate goal of the present research is to incorporate active and passive neck muscle effects in a female finite Element (FE) Human Body Model (HBM). The application of interest is Whiplash Associated Disorders (WAD), which can occur in a low-speed rear-end impact. Two reflex mechanisms, the Vestibulocollic reflex (VCR) and the Cervicocollic reflex (CCR), are integral to maintaining head orientation. Therefore, active muscle modelling in HBMs should address the behaviour of these reflex mechanisms. Female FE HBMs are the focus of the present thesis because of their higher risk of sustaining WAD than males. This model should reproduce kinematics that can be used for global and local tissue injury prediction of WAD. The present thesis was arranged to address the main objective systematically and consists of six studies addressing five research questions. Two human body models representing the 50th percentile population, the VIVA OpenHBM and VIVA+ HBM, were used. The model was developed with and benchmarked against volunteer test data. Based on the collective studies in this thesis, the isolated head-neck model can be used to develop an active muscle controller. A simple, single-link approach was used to design a Proportional-Derivative (PD) controller called Angular Positioned Feedback (APF). This simple controller was convenient to implement and calibrate with available experimental data. Furthermore, reliable parameter identification, such as active muscle controller gains, were obtained via optimization using both head and cervical vertebral kinematics as objectives. A parameter study of different control strategies confirmed that the APF control strategy, combined with parallel damping elements (PDE), was the most effective for recreating volunteer kinematic responses compared to the model with only passive elements, particularly when impact severity was varied. Real-world collision data was used to evaluate the model’s usefulness using injury outcome data for known collision severities. The inclusion of neck muscle responses considerably influenced the cervical vertebral kinematics but only slightly influenced head kinematics before the rebound phase, depending on the head-to-headrest offset. Consequently, a slight difference in global kinematic-based injury criteria such as Neck Injury Criteria (NIC) was observed between a model with and without neck muscle responses. In contrast, significant differences between the two groups were observed for local, tissue-based, whiplash injury prediction. Hypotheses, such as Aldman pressure, require cervical spine kinematics and place higher requirements on the model’s performance. This analysis revealed the need for both global-based injury criteria and local, tissue level analysis to understand how WAD occur. Therefore, whiplash injury prediction would be more reliable using a model with the APF control strategy combined with PDE developed herein, than a model without active neck muscle responses. The FE HBMs with neck muscle responses have been developed and validated for low-speed rear-end impact and WAD analyses. The models have been shown to be robust and able to replicate volunteer head-neck kinematics.

Evaluation of Upgraded Head Restraints: FMVSS 202a

Wed, 25 Oct 2023 16:58:36 GMT

Beginning with vehicle model year 2010, FMVSS 202a established new requirements for head restraints in passenger vehicles. This study evaluates the effectiveness of head restraints in reducing cervical spine injuries, including whiplash injuries, for passenger vehicle occupants using NHTSA’s National Automotive Sampling System Crashworthiness Data System data from 2000 to 2015. The analysis found that female occupants were more likely to suffer cervical spine injuries in rear-end crashes than male occupants. Occupants in full rear-end crashes were more likely to report cervical spine injuries than occupants in partial or side rear-end crashes. The analysis found a statistically significant reduction of 11.1 percent in cervical spine injury protection for occupants in vehicles with head restraints compliant with FMVSS 202a, when compared to occupants in vehicles with a different head restraint or no head restraints. Furthermore, seating positions with FMVSS 202a-compliant head restraints were 10.9 percent more effective in preventing cervical spine injuries than seating positions with FMVSS 202-compliant head restraints.

Normalized vertebral-level specific range of motion corridors for female spines in rear impact

Tue, 22 Feb 2022 10:28:27 GMT

ObjectiveIt is well known that the biomechanical responses of female and male spines are different in rear impacts. Female-specific finite element models are being developed as improvements over generic models. Such advancements need female-specific segmental responses for validation. The objectives of the study were to develop vertebral level-specific range of motion corridors from female human cadaver head-neck complexes exposed to rear impact loading.MethodsPreviously conducted experiments from five human cadaver head-neck complexes were used in this analysis-based study. Briefly, the female head-neck complexes were isolated at the second thoracic vertebral level from the whole body such that the skin and the surrounding tissues of the osteoligamentous complex were intact. The distal end was fixed to the platform of a min-sled testing device. The anterior angulation of T1 was at 25 degrees with respect to the horizontal axis to simulate the normal driver posture. The occipital condyles were directly superior to the T1 body, and the Frankfort plane was horizontal. Rear impact loading were applied at a velocity of 2.6?m/s. The range of motion was defined as the inter-segmental angle at each level of the subaxial spinal column, and it was obtained by tracking the motion of the retroreflective targets that were secured on vertebral bodies and lateral masses of C2 through C7 vertebrae. Data were normalized with respect to the fifth percentile female total body mass, and corridors were developed using the equal stress equal velocity approach and expressed as mean ± 1 standard deviation corridors for each segment.ResultsThe segmental motions of the subaxial cervical spinal column were such that the upper regions responded with flexion while the lower regions responded with extension during the initial accelerative loading phase of the impact, resulting in a non-physiological curvature. During the later phase, all segments were in extension. individual corridors are presented as temporal responses in the body of the manuscript. A comparison of the mean temporal responses at each segment are presented to depict the angulation motion differences within the spinal column.ConclusionsThe present corridors are unique to the female spines. Because female spines have significantly (p?

A review of neck injury and protection in vehicle accidents

Mon, 24 Jan 2022 16:28:31 GMT

Neck injury is one of the most common types of injury in vehicle accidents. The mechanisms of neck injury remain controversial due to the complex structure of the cervical spine and various impact conditions. The aim of the present study is to provide a summary of recent research on neck injury mechanisms, neck injury criteria and neck injury prevention measures. The main types of neck injury resulting from vehicle accidents, including whiplash injury, cervical bone fractures and spinal cord injury, are introduced. Neck injury mechanisms are summarized according to load directions, test or simulation methods, and thresholds by means of impact intensity, load intensity and stress/strain conditions. Neck injury criteria are introduced, including NIC, Nij, Nkm and LNL. Passive and active technologies for neck injury prevention are described and the challenge of neck injury prevention for future intelligent vehicles is discussed.

Prognostic factors for whiplash associated disorders

Wed, 01 Dec 2021 14:45:32 GMT

Disability and chronic pain secondary to low- speed vehicle collisions has been a known condition since the nineteenth century. Today, whiplash-associated disorders (WAD) are the most common personal injuries reported to insurance companies after motor vehicle accidents (MVAs). The prognosis has great variations, spanning from discomfort for a few days to lifelong disability and severe reduction in quality of life. A few well-accepted prognostic factors exist, including high level of pain immediately after the accident, post- traumatic stress and anxiety, and previous history of pain conditions. However, there is no accepted universal pathomechanism and there is a need for additional surveys regarding common characteristics of individuals with poor recovery potential after a whiplash injury. The overall objective of this thesis was to investigate possible risk factors for non- recovery after whiplash trauma. Specifically, we aimed to identify potential associations between non-recovery and involvement of insurance companies, genetic markers, cervical radiological degeneration, and sagittal align- ment. Additionally, we aimed to investigate the effect of an educational video-intervention on the recovery rate. The participants in this thesis are derived from four cohorts. The first cohort comprised individuals aged 18–65 years seeking care at an emergency department (Studies I and III). The second cohort comprised individuals aged 18– 65 years reporting neck pain to insurance companies after an MVA (Studies I and II). The third and fourth cohorts consisted of individuals aged 16–65 years, also recruited from an emergency department after whiplash trauma (Studies IV , V , VI, and VII). In all seven studies of this thesis, inclusion was made by the study team. Information in baseline questionnaires were filled in with regard to demographics and physical and mental health. The patients were followed up with regard to a patient-reported outcome measure (PROM), defined as reported non- recovery or recovery. Secondary outcome measures were level of pain and distress and the Whiplash Disability Questionnaire (WDQ). For Study V, we performed a randomization to either the intervention with the educational video or to a standard information sheet.

Dynamic responses of female volunteers in rear impact sled tests at two head restraint distances

Fri, 06 Aug 2021 16:25:41 GMT

Retrospective evaluation of vehicle whiplash-reducing head restraint systems to prevent whiplash injury in Victoria, Australia

Mon, 11 Jan 2021 11:08:05 GMT

Head restraint systems specifically engineered to reduce the impact of whiplash injury in the event of a rear-end collision were introduced in the late 1990s with the aim of reducing whiplash injury risk that went 'beyond simple geometric improvements’ to head restraints. Whilst studies have shown that whiplash-reducing head restraint systems are highly effective in reducing whiplash injury, these were based on a limited range of systems including Toyota’s Whiplash Injury Lessening (WIL) seating system, Volvo’s Whiplash Injury Prevention System (WHIPS) and the Saab Active Head Restraint (SAHR) and have generally focused on Swedish crash and insurance data. However, there has been no broad real-world crash-based evaluation of the effectiveness of whiplash-reducing head restraint systems currently present in the vehicle fleet that validates the results of these studies in other populations. The objective of this study was to undertake a retrospective evaluation of vehicle whiplash-reducing head restraint systems to prevent whiplash injury using real-world crash data linked to insurance claims data in Victoria, Australia. It was found that whiplash-reducing head restraint systems are associated with a statistically significant reduction in the odds of driver and front seat passenger whiplash injury in a vehicle struck in a rear-end collision of 11.6 % (95 % CI 0.20 %, 21.6 %). The results indicate that whiplash-reducing head restraint systems are an effective technology for reducing the risk of whiplash injury to drivers and front seat passengers in a vehicle struck in a rear-end collision. Considering that around a quarter of all casualty crashes involving passenger and light commercial vehicles are rear-end, the fitment of whiplash-reducing head restraint systems to all vehicles as a standard safety feature would likely see a significant reduction in the incidence of whiplash injury.

An average female head-neck finite element model with reflexive neck muscles

Tue, 08 Sep 2020 14:36:59 GMT

Several factors potentially contribute to the risk of whiplash injuries; one of them is the neck muscle activities. Muscle activities in the neck have been shown to influence the head-neck kinematics during whiplash-like rear impacts. Thus, it is necessary to include the neck muscle responses when conducting a study of head-neck kinematics in a whiplash-like rear-impact condition. Therefore, as the first step, the development which focused on the implementation and optimization of a 50th percentile head-neck FE model with active reflexive neck muscles was conducted in the present thesis. The active muscles were implemented in the existing ViVA OpenHBM, and the work was divided into three studies. The first study concluded that both neck link angular position feedback (APF) and muscle length feedback (MLF) control strategies improved the head kinematics agreement compared to the passive model, but overall, the APF controller performed better. The second study showed that the optimum controller gains and parameters could be identified using optimizations. The final study evaluated different ways to combine APF and MLF controllers. Further study and optimizations are needed to understand the best way to implement and combine MLF controllers with APF controllers.

Importance of intervertebral displacement for whiplash investigations

Wed, 22 Jul 2020 14:48:28 GMT

It is often reported that the physiological rotational limits of adjacent vertebrae in the cervical spine are exceeded in rear-end accidents which play a significant role in Whiplash Associated Disorders (WAD). This paper presents the first analysis of existing experimental and computational intervertebral displacement research. Existing techniques to capture intervertebral displacement in experimental studies can be grouped into three methods: visual targets method, electronic sensors method and X-Ray method. The analysis of intervertebral displacements has led to the development of the intervertebral neck injury criterion (IV-NIC); it has also shown an upward shift of the C5C6 instantaneous axis of rotation and that the flexion changes to extension point between C2 and C4. Furthermore, it is also shown that when a computational model is validated only for the head kinematics, it should not be assumed that the model provides good neck kinematics. Lastly, current rear-impact dummies are incapable of providing true neck kinematics.

Estimating the Number of Traffic Crash-Related Cervical Spine Injuries in the United States; An Analysis and Comparison of National Crash and Hospital Data

Mon, 08 Jun 2020 14:42:51 GMT

Cervical spine injury is a common result of traffic crashes, and such injuries range in severity from minor (i.e. sprain/strain) to moderate (intervertebral disk derangement) to serious and greater (fractures, dislocations, and spinal cord injuries). There are currently no reliable estimates of the number of crash-related spine injuries occurring in the US annually, although several publications have used national crash injury samples as a basis for estimating the frequency of both cervical and lumbar spinal disk injuries occurring in lower speed rear impact crashes. To develop a reliable estimate of the number of various types of cervical spine injuries occurring in the US by comparing data from national crash injury to national hospital ED and inpatient samples. Comparative cross-sectional Cervical spine injury data were accessed, analyzed, and compared from 3 national databases; the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS), Nationwide Emergency Department Sample (NEDS), and the Nationwide Inpatient Sample (NIS). It is estimated that there are approximately 869,000 traffic crash-related cervical spine injuries seen in hospitals in the US annually, including around 841,000 sprain/strain (whiplash) injuries, 2800 spinal disk injuries, 23,500 fractures, 2800 spinal cord injuries, and 1500 dislocations. Because of a highly restrictive inclusion criteria for both crash and injury types, as well as a very small sample size, the NASS-CDS underestimated all types of crash-related cervical spine injuries seen in US hospital emergency departments by 84 %. The injury type with the largest degree of underestimation in the NASS-CDS was cervical disk injuries, which were estimated at an 88 % lower frequency than in the NEDS. National insurance claim data, which include cases of cervical disk injury diagnosed both in and outside of the ED, indicate that the NEDS likely undercounts cervical disk injuries by 92 %, and thus the NASS-CDS correspondingly undercounts such injuries by 99 % or more. Because of a limited sample size and restrictive criteria for both crash and injury inclusion, the NASS-CDS cannot be used to estimate the number of crash-related spinal injuries of any type or severity in the US. The most inappropriate use of the database is for estimating the number of spinal injuries resulting from low speed rear impact collisions, as the NASS-CDS samples fewer than 1 in 100,000 of the cervical spine injuries of any type occurring in low speed rear impact collisions.