Browse Topic: Accident types

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Collapse Strength and Crush Space Analysis in Lateral Side Pole Impact of an Electric Vehicle2026-01-50527/31/2026
High-Voltage Battery (HVB) protection in lateral pole impact is very important due to severe nature of the impact. Unlike frontal impacts, vehicles have limited range of space and capacity to absorb kinetic energy in lateral side impacts. Nowadays, computer-aided engineering (CAE) using finite element analysis (FEA) is utilized routinely to simulate high-speed crash events of varied type, including side pole impact. These CAE applications focus on the analysis and design of HVB when the vehicle structure is well-developed. CAE methods are time-consuming and are not suited during the pre-program stage when the structure is only in a concept stage and not even a reasonable CAD is available/developed in any sense to use these methods. There is no analytical tool available to understand how to define the characteristics of the structure that surrounds and protects the HVB. The primary motive of this publication is to help with this aspect of vehicle planning/development. Needless to state that this procedure can also be used in planning/developing of internal combustion engine (ICE) and hybrid vehicles, as well. The objective therefore is to develop a simple method/procedure that can give reasonably accurate estimation of the collapse/crush force required for a specified crush space and hence protect the critical components, such as HVB and fuel tank. This analytical method also gives some insight into the optimal use of the upper body (rocker and floor cross-members) and underbody (ladder frame) parts. It was found, for a problem under consideration, optimum kinetic energy to be absorbed by the upper body is 32.5% to avoid intrusion into HVB.
Alavandi, Bhimaraddi, Midoun, Djamal, Frank, Randy
Comparison of Female and Male Post Mortem Human Subject Kinematic Responses and Injuries in Rear-Facing Seat Configurations in High-Speed Frontal Impacts2026-22-00077/28/2026
This study investigates female post-mortem human subject (PMHS) responses and injuries, comparing them to previously published data from male PMHS tested at a change in velocity (delta-V) of 56 kph in high-speed rear-facing frontal- impact (HSRFFI) scenarios. Twelve small female PMHS were subjected to the same HSRFFI pulse. The subjects were positioned in reinforced production seats, identical to those from the previous male PMHS studies, and set to recline angles of either 25 or 45 degrees. Instrumentation was used to measure kinematics of the head, spine, pelvis, and ribs. Whole-body kinematics were recorded using motion capture. Female PMHS consistently showed lower head restraint, seatback, and lap belt loads compared to males across all test conditions (Bio Rank System [BRS] scores >1.0), with BRS scores for head restraint forces as high as 4.0. While head and T1 kinematics were consistent with males in all-belt-to-seat (ABTS) conditions (BRS < 1.0), significant differences were found in other body regions (BRS>1.0). Female PMHS had larger head forward rotation and smaller pelvis Z-axis displacement (less ramping) than males in the fixed D-ring (FDR) conditions, leading to major discrepancies (BRS>2.0). In addition, female chest deflection was smaller in one FDR condition (BRS=1.98), and tibia acceleration onset was earlier. Female PMHS sustained severe to critical rib fractures (Abbreviated Injury Scale [AIS]3-5) similar to males. However, five females in the FDR conditions and one in the ABTS condition sustained sacral fractures, an injury not seen in males. Females also had a higher frequency of lower extremity fractures (7 of 12) and vertebral body fractures (7 of 12) compared to males. These findings suggest that existing male PMHS data may not adequately predict responses and injury risks for female PMHS, emphasizing the need for female-specific biomechanical data to enhance safety tools and models in HSRFFI scenarios.
Kang, Yun-Seok, Baker, Gretchen H., Ramachandra, Rakshit, Marcallini, Angelo, Kwon, Hyunjung, Foster, Craig D., Moorhouse, Kevin, Agnew, Amanda M., Bolte, John H.
Geometric Deep Learning–Based AI Framework for Nonlinear Crash Behavior of Extruded Rails15-19-03-00127/27/2026
Extruded Rails are critical energy-absorbing components in automotive structures designed to mitigate impact loads during the frontal collisions. Traditional crashworthiness design relies heavily on computationally expensive finite element simulations and iterative design exploration. This work proposes a machine learning–driven framework for rapid front extruded rails design using a trained geometric deep surrogate model. A design-of-experiments (DoE) was conducted by varying geometric parameters including width, height, and wall thickness of a thin-walled extruded rail structure. For each design variant, LS-DYNA simulations were performed to obtain performance metrics such as mean crush force and peak crush force. These simulation results were used to train an AI surrogate model capable of predicting crash responses directly from geometric parameters. The proposed approach significantly reduces computational cost by replacing repeated high-fidelity crash simulations with machine learning surrogate predictions. By enabling fast and accurate evaluation of crash response metrics, the workflow shortens design cycles and supports sustainability-driven crashworthiness assessment by reducing simulation resource usage. The framework establishes a scalable, simulation-driven engineering pathway across vehicle platforms and provides a foundation for future closed-loop, AI-assisted crash design workflows.
Kumar, Manik, Srinivasan, Sriram
A Framework for Precautionary Safety for Automated Driving Systems—Toward Tactical Decisions Fulfilling Quantitative Risk Acceptance Criteria12-09-04-00287/8/2026
Safety of Automated Driving Systems (ADSs) is arguably one of the main remaining barriers before widespread market deployment. While there exists a plethora of methods for planning a trajectory that fulfils certain constraints, what those constraints should look like, to enable effective planning of safe trajectories, is still being discussed. In this article, we generalize the concept of Precautionary Safety (PCS) and present a framework providing constraints on the tactical and operational decisions of the ADS. Such constraints consider the ADS’ capabilities, the external conditions, knowledge of statistically relevant events and behaviors of other traffic actors, as well as the controllability of these events. The proposed framework enables assessment of the statistical fulfilment of quantitative risk acceptance criteria (QRACs), including requirements on accident, injury, and fatality rates. The framework further provides a means to dynamically adapt the constraints used for trajectory planning, i.e., to adapt the driving to the situation at hand. A case study, considering a possible collision scenario with a jaywalking pedestrian and a rear-end collision with a trailing vehicle, is provided to showcase the applicability and usefulness of the presented framework. The simulation-based case study displays the safety benefits from considering QRACs with multiple injury risk levels and further shows how the proposed PCS framework can be applied in practice.
Gyllenhammar, Magnus, de Campos, Gabriel Rodrigues, Sandblom, Fredrik, Törngren, Martin, Fredriksson, Jonas
Female PMHS Thoracic Biomechanical Response Corridors with Preliminary Consideration of the Influence of Breast Tissue in Frontal Impacts2026-22-00066/24/2026
Thoracic injuries are common for belted occupants in frontal motor vehicle crashes. However, there remains a lack of female post-mortem human subject (PMHS) data in the literature to generate female-specific biomechanical response corridors and evaluate engineering tools such as anthropomorphic test devices (ATDs) and computational human body models (HBMs). Additionally, the effect of breast tissue on thoracic response has not been directly investigated despite female ATDs and HBMs having features representing breasts. As such, this study sought to utilize simplified frontal hub impacts to (1) generate female PMHS thoracic response corridors both with breasts positioned with a bra and without breasts (no bra) and (2) preliminarily explore the influence of breasts on the thoracic responses of female PMHS. Twelve female PMHS (9 small and 3 midsize) were subjected to frontal impacts at mid-sternum with a 14.0 kg circular impactor at 4.3 m/s in conditions with and without breasts. Force versus deflection (FD) response corridors were generated, and comparisons were made between groups and to scaled FD corridors representing female response. Overall, female PMHS with and without breasts displayed differences in FD response compared to scaled corridors in terms of the shape of the initial response and peak force and deflection. Additionally, female PMHS with breasts produced lower peak force and greater peak deflection compared to those without breasts. These results suggest the importance of collection and evaluation of female biomechanical data that can be used for continued evaluation of female-specific safety tools as well as the further reduction of injury risk for all occupants during motor vehicle crashes.
Baker, Gretchen H., Kang, Yun-Seok, Marcallini, Angelo, Lang, Ryan, Hutter, Erin, Moorhouse, Kevin, Agnew, Amanda M.
Occupant Sex Equity and Vehicle Safety: Historical Activities, Research, and Countermeasure2026-22-00025/28/2026
Since 2019, sex equity in traffic crashes has been a highly debated topic in vehicle safety, especially following the 2019 study by Forman et al. (1) claiming that female occupants face a 73 percent greater risk of serious injury in frontal crashes compared to male occupants. This was soon followed by a Consumer Reports Article by Keith Barry (2), which attempted to identify underlying factors contributing to the higher risk. These have been embraced by several parties since 2019. Firstly, it was alleged that vehicle design practice over the last four decades considered safety for the male population only and ignored that of the female as evidenced by the exclusive use of the mid-sized male Anthropomorphic Test Devices (ATDs) in Regulatory and Safety Ratings tests and not with an average sized female ATD. The absence of such an ATD for testing of vehicles “set the course for four decades’ worth of car safety design, with deadly consequences” (2). Secondly, although there is a recognition of the fact that Regulatory testing with a Small Female ATD, the Hybrid III-05F, was introduced in the FMVSS208 in 2003, this ATD was only a scaled version of the average male ATD of the 1970’s implying that this ATD is incapable of driving the design of restraint systems for females due to “They’re put together differently. Their material properties—their structure—is different” (2). Thirdly, according to a quote “These same trends have been observed in many, many studies in the past.” We assume that the trends refer to the apparent disparity in safety of females when compared to those of males. This document aims to outline historical activities, associated research and the development of countermeasures addressing crashworthiness concerns related to vehicle safety for females, as well as factors affecting both males and females, such as age-related impacts. This paper deals mainly with the frontal crash modes, mentions side impacts briefly as it affected designs of inflatable restraints for side impact to protect the smaller portion of the population from inflation induced injuries but the history behind the use of female ATDs by IIHS and NHTSA in full scale testing is not covered. Where ever possible, the time periods of reported activities related to female safety have been divided to pre-1997 corresponding to a change in US frontal crash regulation to address serious-to-fatal injuries to females and children, between 1997 to 2003 corresponding to the proposal by Canada for its frontal impact standard, and between 2003 and 2006 when the Advanced Restraint Regulation in the US FMVSS 208 was promulgated. This was followed by activities between 2007 and 2019, and post 2019 period.
Prasad, Priya, Dalmotas, Dainius J.
Advanced Tool for Traffic Crash Analysis: An AI-Driven Multi-Agent Approach to Pre-Crash Reconstruction09-14-01-00335/4/2026
Traffic collision reconstruction traditionally relies on human expertise and, when performed properly, can be incredibly accurate. However, attempting to perform pre-crash reconstruction, i.e., reconstructing the driver and vehicle behaviors that preceded the actual crash, poses significantly more challenges. This study develops a multi-agent artificial intelligence (AI) framework that reconstructs pre-crash scenarios and infers vehicle behaviors from fragmented collision data. We present a two-phase collaborative framework combining reconstruction and reasoning phases. The system processes 277 rear-end lead vehicle deceleration (LVD) collisions from the Crash Investigation Sampling System (CISS; 2017–2022), integrating textual crash reports, structured tabular data, and visual scene diagrams. Phase I generates natural language crash reconstructions from multimodal inputs. Phase II performs in-depth crash reasoning by combining these reconstructions with the temporal event data recorder (EDR). This enables precise identification of striking and struck vehicles while isolating the EDR records most relevant to the collision moment, thereby revealing crucial pre-crash driving behaviors. For validation, we applied it to all LVD cases, focusing on a subset of 39 complicated EDR cases where multiple EDR records per collision introduced possible ambiguity (e.g., due to missing or conflicting data). Ground truth was established via consensus between manual annotations (two independent researchers), with a separate large language model (LLM) used only to flag possible conflicts for re-checking. In the full end-to-end evaluation, the framework achieved 100% accuracy across all 4155 trials (277 cases × 5 runs × 3 models), with three reasoning models producing identical outputs, confirming that performance derives from the structured prompt design rather than model-specific characteristics. In contrast, research analysts without specialized reconstruction training achieved 92.31% accuracy on the same 39 complex cases. In separate ablation experiments on the 39 complicated EDR cases, where one randomly selected Phase I output from the full end-to-end evaluation was fixed as the unified input for Phase II and each model was tested with 10 independent runs, removing the structured reasoning anchors reduced case-level accuracy from 99.7% to 96.5%, with errors spreading from a single output type to multiple analytical dimensions. The system maintained robust performance even when processing incomplete data. This zero-shot evaluation, conducted without any domain-specific training or fine-tuning, demonstrates that the framework’s effectiveness stems from its multi-agent architecture and prompt engineering, offering a scalable approach for AI-assisted pre-crash analysis.
Xu, Gerui, Chen, Boyou, Guo, Huizhong, LeBlanc, Dave, Kusari, Arpan, Yarbasi, Efe, Ahmed, Ananna, Sun, Zhaonan, Bao, Shan
Rear-Impact Crash Injury Patterns and Predictors: Insights from Contemporary CISS and CIREN Field Data09-14-01-00295/4/2026
The objective of this study was to investigate occupant injury patterns and predictors in rear-impact crashes using recent US field data. Cases were queried from the Crash Investigation Sampling System (CISS, 2017–2023) and the Crash Injury Research and Engineering Network (CIREN, 2017–2024), yielding 1923 front-row outboard occupants from 1533 crashes. Crash documentation and vehicle photographs were manually reviewed to classify seatback deformation magnitude and secondary impact severity. Multivariable logistic regression models estimated associations between occupant, vehicle, and crash characteristics and Abbreviated Injury Scale (AIS) ≥ 2 and AIS ≥ 3 injury outcomes across body regions. Sensitivity analyses included CISS-only, weighted, single-event, and interaction models. Thoracic injuries were further subdivided into skeletal and cardiopulmonary categories. Findings reflect associations within the pooled CISS + CIREN analytic sample rather than nationally representative injury rates. Seatback deformation and multievent crash classification are proxy measures and may introduce misclassification and residual confounding. A total of 188 occupants sustained AIS ≥ 2 injuries and 81 sustained AIS ≥ 3 injuries. Head injury was the most frequent AIS ≥ 2 outcome, while thoracic injury was the most frequent serious injury outcome, accounting for 60% of AIS ≥ 3 cases. Across AIS ≥ 2 and AIS ≥ 3 models, crash severity (delta-v) was the most consistent predictor of injury. Age was strongly associated with injury across most AIS ≥ 2 outcomes and several AIS ≥ 3 models, particularly for overall maximum Abbreviated Injury Scale (MAIS) and thoracic injury. Seatback deformation was associated with injury across multiple models after controlling for crash severity and occupant characteristics, with severe deformation showing stronger associations with AIS ≥ 3 outcomes. Unbelted status was associated with abdominal, pelvic, and lumbar spine injury. Female sex was associated with thoracic injury, primarily attributable to cardiopulmonary rather than skeletal injury. These findings highlight statistical associations between seatback deformation severity, restraint status, occupant characteristics, and injury outcomes in rear-impact crashes.
Lockerby, Jack, Rudd, Rodney
Characterization of Front Row Occupants Involved in Motor Vehicle Crashes Compared to ATDs and the U.S. Population09-14-01-00275/4/2026
Currently, adult anthropomorphic test devices used in regulatory and consumer information crash testing in the United States are targeted to represent a small female (5th percentile) and an average male (50th percentile). The anthropometry determined previously might not represent the current population, or as investigated in the current study, those that are at least moderately injured during a motor vehicle crash. The objective of this study was to use field data to determine if the current frontal anthropomorphic test devices are representative. Data from the National Automotive Sampling System–Crashworthiness Data System (2010-2015) and Crash Investigation Sampling System (2017–2023) were queried for sex, age, size, and injury information for front seat occupants in frontal crashes. Additional datasets used were from the National Trauma Data Bank and the Centers for Disease Control and Prevention. According to field data, the most frequently injured female and male is approximately 164 cm tall, weighing 72 kg and approximately 177 cm tall, weighing 81 kg, respectively. The distribution of those injured in frontal crashes aligns with all crash types and the current United States population. Differences between anthropomorphic test device specifications and recent data (particularly weight) should be the focus of future work.
McNeil, Elizabeth, Atwood, Jonathan, Rudd, Rodney, Craig, Matthew
Frontal Crash Classification and Occupant Outcomes from 2017 to 2023 US Field Cases09-14-01-00245/4/2026
This study provides an updated characterization of real-world frontal crash types—considering overlap and obliquity—based on their overall frequency and associated injury outcomes. The results of this study will support an evaluation of how well NHTSA’s frontal oblique crash test condition addresses the current population of serious frontal crashes, as compared to frontal test modes in existing crashworthiness programs. U.S. field crash data from 2017 to 2023 were analyzed to classify frontal crashes by coded damage characteristics. Oblique frontal crashes were defined as those with principal direction of force between 10°–40° and 320°–350°. Non-ejected belted first and second row occupants in model year 2000 and newer passenger vehicles absent a rollover event were included. Occupants were stratified by sex, age, and body mass index, and injury outcomes based on moderate, serious, and fatal thresholds were analyzed across crash configurations. Among the belted first row occupants considered in this study, more than 45% were exposed to oblique crashes while full overlap colinear crashes accounted for 18% of the occupants. Oblique crashes represent a disproportionately large number of AIS 3+ injured and fatal occupants. Older occupants and females showed a trend of higher injury frequency despite less exposure. Full overlap crashes still account for a representative portion of serious injuries among frontal crashes. Limitations include restriction of cases to those with complete vehicle and occupant details. Assessment of impact type was dependent on generic vehicle class-specific reference values. The findings reinforce the enduring relevance of oblique frontal crash conditions which remain a substantial contributor to serious injuries and fatalities, especially for older adults and female occupants.
Rudd, Rodney W.
Interactions of Rear-Facing Child Restraints in Frontal Crash Tests09-14-01-00105/4/2026
The aims of this study were to investigate the kinematics of child anthropomorphic test devices in a large sample of rear-facing child restraint system installations and the effects of anti-rebound features and load legs on the kinematics of rear-facing child anthropomorphic test devices. The test matrix included a general sample of 70 rear-facing child restraint system installations to observe trends in frontal crash tests; 14 full-scale crash tests with paired comparisons to investigate the effect of anti-rebound features; and five paired comparisons of rear-facing child restraint systems installed with and without a load leg. The paired t-test was used to determine the statistical significance of differences in kinematic responses. In the general sample, 84% of anthropomorphic test devices in infant seats with the base in outboard seats interacted with the first-row seat. In 52% of tests, the anthropomorphic test device head directly contacted the front seatback. Head accelerations > 80 g were caused by interactions between: the child restraint system and front seatback; the anthropomorphic test device head and the interior surface of the child restraint system; or the anthropomorphic test device head and front seatback. In the anti-rebound sample, head contact on rebound occurred in three infant seat installations, and all were associated with head resultant accelerations ≤33 g. The mean paired difference in head 3 ms clip was negligible (p > 0.05). In the load leg sample, the load leg limited forward excursion and forward rotation of the rear-facing child restraint system, thereby contributing to the containment of the anthropomorphic test device within the boundary of the child restraint system shell. In this study, anti-rebound features did not improve the kinematics of pediatric anthropomorphic test devices. The feasibility of including the use of the load leg in the Canadian regulatory test protocol should be explored.
Tylko, Suzanne, Tang, Kathy
The Effect of Initial Foot Position on THOR-50M and THOR-05F Lower Leg Response in a Realistic Vehicle Buck09-14-01-00085/4/2026
This study aims to explore and evaluate the effect of various foot positions on the kinematic and kinetic response of the lower extremity during frontal crashes using a realistic vehicle interior. Frontal impact sled tests were performed with the Test Device for Human Occupant Restraint, 50th-percentile Male (THOR-50M) and Test Device for Human Occupant Restraint, 5th-percentile Female (THOR-05F) anthropometric test device (ATD) in the driver’s seat of a midsize SUV testing buck (with realistic interior components including an instrument panel with steering wheel and steering wheel airbag, seat, three-point seat belt with pretensioner and force-limiter, accelerator pedal, brake pedal, knee airbag, and seat belt retractor pretensioner). Six sled tests were performed in two principal directions of force (PDOF) [three each in frontal (0°) and oblique (−20°) configurations]. The right foot was positioned on the accelerator pedal, fully on the brake, and half on the brake. A single test was conducted with the THOR-05F in an oblique configuration with the foot on the accelerator. Ankle response was analyzed from internal ATD instrumentation. Restraint engagement was found to be consistent across all testing cases. Ankle moment and angle varied based on PDOF and the tested foot condition. Right ankle moment ranged from 70 to −70 Nm in inversion/eversion. Right ankle angles ranged from 37° inversion to 28° eversion. Left ankle moment ranged from 10 to −41 Nm in inversion/eversion. Left ankle angles ranged from 10° eversion to 23° inversion. Differences in lower extremity motion and loading were observed for each testing condition. Placing the foot on the accelerator pedal produced greater ankle moment than either brake pedal condition. Placing the foot on the brake pedal resulted in the highest dorsiflexion angle response. Obliquity increased ankle moment and rotation for both ankles. The United States New Car Assessment Program (US-NCAP) foot position with an oblique PDOF created the highest ankle moment while the in-line brake position in oblique created the highest dorsiflexion rotation. By combining these findings with other efforts focused on naturalistic driving and foot positioning, these results might aid in development of additional testing practices that might enhance our understanding of the lower extremity in nonstandard initial positions.
Noss, Junior, Donlon, John-Paul, Morris, Anna, Samier, Germain, Park, Joseph, Forman, Jason
Front-Row Seatback Contact for Pediatric Occupants Seated in Rearward-Facing Infant Child Restraint Systems during Frontal Crashes09-14-01-00195/4/2026
Using a subset of the Transport Canada dataset of rearward-facing CRS in full-frontal rigid barrier vehicle tests, the aim of the current study was to evaluate CRS and/or ATD head contact with the front-row seatback and categorize the contribution to the peak ATD head acceleration. For 33 cases of ATDs seated in rearward-facing CRS models installed in the second-row outboard seats across 19 vehicle tests, high-speed video footage was analyzed to identify instances and timings of CRS and/or ATD head contact with the front-row seatback. The timing of contact was compared to the ATD head acceleration time history to identify instances of “contributory contact” with the front-row seatback, which was defined as contact occurring before the ATD head acceleration was within 10 g of the peak. ATD contributory contact cases involved both the ATD head and CRS contacting the front-row seat, whereas CRS contributory contact cases involved only the CRS, but not the ATD head, contacting the front-row seat. No contributory contact cases were those that involved either ATD or CRS contact with the front-row seatback, but the contact occurred after the time point associated with 10 g below the peak ATD head acceleration. No contact cases were those that did not involve either ATD or CRS contact with the front-row seatback. Contributory CRS and/or ATD contact with the front-row seatback was found to be associated with increased head injury risk. Therefore, the energy-absorbing properties of the CRS head restraint and/or front-row seatback are likely important considerations regarding frontal crash protection for rearward-facing pediatric second-row occupants. Impact velocity, location, and angle were able to be calculated for two cases that involved contributory ATD contact with the front-row seatback. Such data could be used as boundary conditions for physical testing of front-row seatbacks and computational modeling.
Patton, Declan A., Tang, Kathy, Tylko, Suzanne, Arbogast, Kristy B.
Comparative Analysis of Thoracic Injury and Causative Factors across Sexes in Serious Frontal Motor Vehicle Collisions in the Crash Injury Research and Engineering Network Database09-14-01-00315/4/2026
This study investigated sex-specific differences in thoracic injury prevalence, causation, and rib fracture patterns among seriously injured occupants in frontal motor vehicle collisions. Crash Injury Research and Engineering Network (CIREN) data from 2005 to 2022 included 793 front-seat occupants aged 16 years and older with Abbreviated Injury Scale 2+ thorax injury, representing 1802 thoracic injuries. Injuries were grouped as rib fracture, sternum fracture, hemo/pneumothorax, lung injury, heart injury, and other. A weighted scoring system captured contributions of involved physical components to each injury. Logistic and linear regression with generalized estimating equations assessed sex associations with injury presence and causation. Two models were estimated: a comprehensively adjusted model including demographic, crash, vehicle, restraint, and airbag deployment, and a simplified model adjusting for age, body mass index, delta-V, and occupant role. Among occupants with AIS 2+ thoracic injuries, sex-specific differences were observed in injury patterns and causation. Females were less likely than males to sustain lung injuries (OR = 0.70, p = 0.038) and more likely to sustain rib fractures (OR = 1.25, p = 0.006). Females had higher odds of rib fractures attributed to seatbelt loading in both models (Full: OR = 2.20, p = 0.005; Simplified: OR = 1.55, p = 0.021). Females were less likely than males to sustain lung injuries (OR = 0.17, p = 0.042) and hemo/pneumothoraces (OR = 0.15, p = 0.044) from instrument panel loading. Steering wheel, airbag, and other components showed no significant sex-specific associations with thoracic injury. Rib fracture patterns showed clusters along the seatbelt path in belted occupants and a more diffuse pattern in unbelted occupants, with minimal significant findings of differences between sexes. These findings contribute to the growing evidence of sex-specific injury patterns and may inform future research on injury prediction and prevention strategies. However, this dataset includes only occupants with AIS 2+ thoracic injuries and therefore cannot be extrapolated to the general population or to collisions outside those represented in the sample.
Armstrong, William, Devane, Karan, Hsu, Fang-Chi, Heilmann, Nina, Sink, Joel, Miller, Anna N., Kiani, Bahram, Martin, R. Shayn, Stitzel, Joel D., Weaver, Ashley
Regional-Specific Patterns of Abdominal Injury in Belted Male and Female Frontal Crash Occupants: Insights from Redefined Anatomical Mapping09-14-01-00025/4/2026
Research Question/Methods The study examined abdominal injuries of 87 belted occupants in CIREN frontal crashes for sex-based differences in abdominal injury patterns. It introduced a more anatomically detailed method for identifying injury locations in an abdominal-pelvic region that includes skeletal structures. The study introduces and applies a novel Abdominal New Injury Severity Score (AbNISS) to address limitations of traditional AIS coding in capturing sex-based differences in injury patterns. The operative reports/EDR/imaging data in CIREN cases enabled identification of sex-specific crash outcomes. The dominant analytical motif is Bertrand Russell’s knowledge by acquaintance and definite descriptions. Results Females had a higher rate of moderate to severe abdominal injuries than males: Only females sustained AIS 5 injuries, lumbar Chance fractures, posterior pelvic arch injuries, and more AIS 2, 3, and 4 injuries, with more injuries in superior-mid, left-superior, and medial-mid-abdominal zones. Males had more in the medial-inferior zone. 13 females had muscle ruptures. Four had combined muscle and Morel–Lavallée injuries, and four had Morel–Lavallée injuries alone. 13 of 14 males had muscle ruptures only. Pelvic morphology: Statistically significant (p < 0.05) sex-based difference in pelvic aspect ratios: Females: 1.37 ± 0.053, with the male ratio of 1.28 ± 0.079. By incorporating anatomical precision and enhanced injury mapping, it supports the development of more representative ATD/human body models. Discussion and Limitations Limitations of the study include its retrospective design, possible inconsistencies in clinical documentation, and challenges in applying AbNISS coding to non-CIREN datasets due to specificity constraints.
Halloway, Dale, Curry, William, Somasundaram, Karthik, Pintar, Frank
Injury and Kinematics of Obese PMHS in Frontal Impacts with Reclined Seating09-14-01-00035/4/2026
Objective: This study investigated injury outcomes and body kinematics in obese occupants exposed to frontal impacts while seated in reclined postures. With increasing interest in non-traditional seating configurations and a growing population of obese vehicle occupants, the objective was to evaluate how seat stiffness and restraint features influence injury patterns and whole-body excursions. Methods: Nine obese post-mortem human surrogates (PMHS; mean age: 64 years, stature: 1.70 m, body mass: 102 kg, BMI: 35 kg/m2) were tested under frontal impact conditions simulating a delta-V of 50 kph. All specimens were seated on a spring-controlled seat with a 45° reclined seatback and restrained by a three-point belt system with pretensioner and load limiter. Three configurations were evaluated: (1) stiffer seat, (2) softer seat, and (3) stiffer seat with a knee bolster 100 mm from the knees. Each subject underwent one test. Whole-body kinematics were captured using a VICON motion analysis system, and injury outcomes were assessed through radiographs, CT imaging, and autopsy, with severity classified by Maximum Abbreviated Injury Scale (MAIS) and Injury Severity Score (ISS). Results: Softer seats produced substantially greater downward (+Z) pelvic displacement compared with stiffer seats. The knee bolster effectively reduced both downward and forward excursions of the lower torso. Rib cage and pelvic injuries were most frequent, with the highest severity observed in softer seat tests. Mean ISS values were: STIFF—27, 13, 27; SOFT—34, 27, 14; STIFF-KB—22, 0, 13. Discussion: Reduced seat stiffness combined with increased occupant mass contributed to greater excursions and anterior torso injuries, whereas the knee bolster mitigated excursion and injury severity. Findings are limited by sample size and test conditions; broader evaluation with production seats is needed to confirm trends and support countermeasure design.
Somasundaram, Karthik, Yoganandan, Narayan, Pintar, Frank
Geometric Variabilities and Their Effects on Impact Responses in Midsize Male and Female Occupants09-14-01-00255/4/2026
The objective of this study is to use parametric human body models (HBMs) to understand how geometric variability among individuals who have the same sex, stature, and body weight may affect the impact responses and injury outcomes, using midsize male and midsize female populations as representative cases. Methods were developed to quantify skeletal and external body surface variations using principal component analysis, regression, and residual error analysis. Based on this analysis, nine midsize male and nine midsize female geometric models were created, focusing on ribcage and pelvis variations, which account for most of the observed variability. These geometries were then applied to morph the simplified Global Human Body Model Consortium (GHBMC) midsize male model, producing 18 distinct HBMs. Each morphed HBM was subjected to nine impact scenarios, resulting in a total of 162 simulations to assess the effects of geometric variability. Substantial geometric variation was observed in the ribcage and pelvis, while the femur and tibia showed minimal variability for both midsize males and females. All morphed HBMs had good mesh quality, and all crash simulations terminated normally without error. Component-level tests showed relatively minor differences in impact responses among HBMs with identical sex, stature, and body weight. However, the United States New Car Assessment Program (US-NCAP) frontal crash simulations revealed considerable differences in injury risk, especially in the front passenger position. These findings highlight the importance of accounting for geometric variability, even among HBMs with the same sex, stature, and body weight, when evaluating injury risks in severe frontal crashes. It is especially important to consider ribcage geometry variations, which could impact occupant sitting height, posture, and injury risks at different body regions in frontal crashes. This study demonstrated that future virtual testing frameworks using HBMs should consider human geometric variations, especially in the ribcage and pelvis, when assessing injury risks in vehicle frontal crashes.
Hu, Jingwen, Lin, Yang-Shen, Boyle, Kyle, Khandare, Sujata, Bonifas, Anne, Reed, Matthew P., Hasija, Vikas
Characterization of Fatal Cyclist Collisions Involving Nine Vehicle Types Traveling at Low and High Speeds in Japan09-14-01-00055/4/2026
To reduce traffic fatalities through vehicle safety measures, particular attention must be given to cyclist-related fatalities. Clarifying the characteristics of hazardous events leading to cyclist fatalities, not only by vehicle speed range but also by vehicle type, is essential and should be based on analyses of real-world accident data. Accordingly, this study aimed to characterize fatal cyclist accidents involving vehicles traveling at low and high speeds in Japan. We used macro accident data from the Japanese Institute for Traffic Accident Research and Data Analysis covering the period from 2013 to 2022. Based on nine vehicle types, we investigated the effects of road type, vehicle behavior, and accident type on cyclist fatalities. Additionally, we identified the five most frequent accident scenarios separately for each low- and high-speed category. At signalized intersections, the proportions of cyclist fatalities involving vehicles traveling at low speeds were higher than those involving vehicles traveling at high speeds across all vehicle types. In contrast, on straight roads, the proportions at low speeds were lower than those at high speeds for all vehicle types. In the low-speed range, cyclist fatalities within the top five scenarios accounted for 65% of all fatalities, with the most frequent scenario occurring at signalized intersections during left-turn maneuvers, where heavy-duty trucks accounted for 86% of the fatalities. In the high-speed range, cyclist fatalities within the top five scenarios accounted for 71% of all fatalities. The most frequent high-speed scenario involved crossing collisions at unsignalized intersections when vehicles traveled straight, with light passenger cars and sedans accounting for 29% and 24% of the fatalities, respectively. These findings provide valuable insights for the development of targeted traffic safety regulations and vehicle technologies aimed at reducing vehicle–cyclist collisions across different speed ranges.
Matsui, Yasuhiro, Oikawa, Shoko
Assessing Injury Prediction with Human Body Models: Application to Rib Fracture Risk Prediction Using SAFER HBM09-14-01-00235/4/2026
As a consequence of the introduction of mathematical human body models (HBMs) in consumer information programs, there is an increased need for reliable methods that can demonstrate and build trust in the capability of HBMs to predict human response and injury risk in crashes. Therefore, a framework for validation of strain-based injury prediction is proposed. The framework comprises stepwise validation with the final step to validate the utility of risk predictions by means of the area under the curve (AUC) combined with Brier scores. SAFER HBM V11.1.0 previously validated at component and body part levels was selected for the demonstration of the final step of the framework to validate the capability to predict fracture risk in frontal, oblique, and lateral loading. For frontal loading, five postmortem human surrogate (PMHS) test series with 43 PMHS (age range: 19–88 years) were reconstructed. The predicted rib fracture risk for 2+ and 3+ fractured ribs was compared to the number of fractured ribs sustained by the PMHS. Using the framework, the SAFER HBM was for frontal impact analysis found capable of predicting 2+ fractured ribs with an AUC of 0.90 and 3+ fractured ribs with an AUC of 0.89. For oblique and lateral impacts, three PMHS test series including 47 PMHS (23 with 0, 22 with 2+, and 20 with 3+ fractures) were reconstructed, and SAFER HBM rib fracture risk predictions obtained AUC values of 0.84 and 0.87 for 2+ and 3+ fractured ribs, respectively. In the frontal load case, the Brier score was 0.14 for the Number of Fractured Ribs (NFR) 2+ model and 0.17 for the NFR 3+ model. In the lateral/oblique load case, Brier scores were 0.20 and 0.18 for the NFR 2+ and NFR 3+ models, respectively. The proposed framework is a suitable method to objectively assess the utility of HBM injury predictions, demonstrated with the SAFER HBMs capability to predict rib fracture risk.
Pipkorn, Bengt, Niranjan Poojary, Yash, Osth, Jonas, Larsson, Karl-Johan, Iraeus, Johan
Neck and Spinal Responses in the Reclined Large Omnidirectional Child Anthropomorphic Test Device with and without a Booster Seat during Far-Side Lateral Oblique Impacts09-14-01-00115/4/2026
Objective The objective of this study was to examine the Large Omnidirectional Child (LODC) anthropomorphic test device (ATD) neck and spine responses in reclined seating configurations with and without a backless belt-positioning booster (BPB) in far-side lateral oblique impacts. Methods The LODC was seated on a production passenger seat with an integrated seatbelt and tested in nine lateral oblique impact (80° from frontal) sled tests (31.3 km/h). A condition with a nominal seatback angle (~25°) with a backless BPB and two conditions with reclined seatback angles (~45° and ~60°) with and without a BPB were compared. Each condition was repeated, except for the 60° without BPB. Peak upper neck tension force and lateral moment, T1, T6, and T12 lateral rotation, lumbar axial and lateral shear forces, and lumbar axial moment (Mz) were extracted. Results With noBPB, upper neck tension (45° noBPB: 2.0 ± 0.1 kN; 60° noBPB: 1.8 kN) and lateral moment (45° noBPB: 31.7 ± 2.3 Nm; 60° noBPB: 29.2 Nm) were greater than with the BPB in all seatback angles (25° BPB: 1.3 ± 0.04 kN; 21.6 ± 0.1 Nm; 45° BPB: 1.2 ± 0.1 kN, 22.5 ± 2.3 Nm; 60° BPB: 1.2 ± 0.03 kN, 17.6 ± 0.7 Nm). Thoracic spine rotation was smaller in reclined conditions with noBPB (41°–59°) than with BPB (63°–80°). Lumbar axial forces decreased with increasing seatback angle with the BPB (from 2.2 to 1.2 kN). Lumbar Mz showed increasing unbelted shoulder rotation toward the seatback with increasing seatback angle (from 29.8 to 37.8 Nm) with the BPB but not without. Discussion The presence of the BPB may improve neck and spine coupled motion during far-side lateral impacts. However, increased lumbar Mz with the BPB in recline seatbacks requires further understanding.
Graci, Valentina, Humm, John, Hauschild, Hans
Biomechanical Responses and Injuries of Male Post-Mortem Human Subjects in Rear-Facing Frontal Impacts with Unreinforced Airbag-Equipped Production Seats09-14-01-00305/4/2026
Previous rear-facing post-mortem human subject (PMHS) studies utilizing a reinforced seat have prompted questions as to whether the seat could have been a contributing factor to the severe rib and pelvis injuries observed in those experiments. In response, a recent PMHS study used an unreinforced seat in a similar experiment, which was expected to mitigate severe injuries by dissipating energy from seatback deformations. However, the PMHS tested in the unreinforced seat sustained even more severe rib fracture numbers than in the reinforced seat. No studies have investigated how additional variables (i.e., countermeasures) may influence rib fractures in high-speed rear-facing frontal impacts (HSRFFI). Therefore, this study aimed to explore the effect of an airbag-equipped seat (AES) on male PMHS responses and injuries. Rear-facing sled tests were conducted using five mid-size male PMHS seated in the AES at ΔV of 56 km/h: PMHS1 with no airbag as a baseline, PMHS2 with a seatback airbag (SA), PMHS3 with an extended seatback airbag (ESA), and PMHS4 and 5 with ESA and a wedge airbag (ESA+WA). An instrument panel (IP) and windshield were installed behind the seat to mimic realistic interior vehicle compartments. A chestband at mid-sternum, 6-degree motion blocks at the head, T1, T4, T8, T12, pelvis, and extremities, as well as rib strain gages and rosettes were installed on PMHS to understand potential mechanisms of injuries. A motion capture system was used to quantify whole-body PMHS and seatback kinematics. Maximum seatback rotation was 38.1° in the baseline test and 20.3°–25.1° with AES. Peak chest A-P compression in the anterior-posterior (A-P) direction was 25.7 mm for baseline and 7.3 mm–35.2 mm with AES (23.7 mm for SA, 7.3 mm for ESA, 35.2 and 8.7 mm for ESA+WA). The number of rib fractures (NRF) was high in baseline (32), SA (25), and ESA (27) conditions, but was reduced in ESA+WA (6 and 13). Strain rosette data indicated upward directions of principal strains on the posterior ribs, likely due to I-S deformation of the PMHS thoraces. Responses from thorax instrumentation showed that peak chest deflection (A-P) alone did not fully explain NRF, especially as rib fractures in all tests occurred after peak deflection in this direction. Instead, maximum principal strains in the I-S direction (shear), confirmed by strain rosette data, likely influenced rib fractures. ESA+WA effectively supported PMHS, maintaining upright postures and minimizing I-S chest shear, which reduced NRF. Limitations include a small sample size, possible age-related injury effects, and seat designs intended for low-speed rear impacts, not HSRFFI. Compression and shear loading to the PMHS thoraces were observed in HSRFFI. The shear loading was likely due to the large upward thorax deflection induced by the ramping motion and seatback rotation. One of the AES, ESA+WA, effectively maintained an upright spine and reduced NRF. This study offers important information for improving current safety tools and designing rear-facing countermeasures for automated driving systems.
Kang, Yun-Seok, DeWitt, Timothy, Wensink, Timothy, Marcallini, Angelo, Jung, Yong Hyun, Lee, Dong Gil, Harm, Jae Jun, Ko, Seokhoon, Hunter, Randee, Agnew, Amanda M.
Statistical Assessment of Pretensioner and Load Limiter Effects on the Large Omnidirectional Child ATD Response in Frontal Impacts2026-01-05504/7/2026
Enhancing child occupant protection requires a clear understanding of how seatbelt restraint parameters influence crash injury metrics. Real-world vehicles mostly include pretensioner and load limiter technologies to mitigate injuries, but rear seat restraints often do not include these. The FMVSS No. 213 test bench closely represents current restraint systems but does not involve such active vehicle restraint features. This study explores the response of the Large Omnidirectional Child ATD to evaluate potential injury mitigation under FMVSS No. 213 frontal sled test conditions. A simulation-based full factorial design was implemented in LS-DYNA to vary pretensioner retraction, retractor load-limiting thresholds, and webbing payout, with injury measures including head acceleration, head excursion, chest compression, and abdominal pressure twin sensors (APTS). Statistical evaluation using analysis of variance (ANOVA) and Tukey-Kramer post-hoc tests quantified main and interaction effects. Pretensioners consistently reduced head excursion and acceleration, while load limiters lowered chest compression but increased excursion, illustrating a performance trade-off. Webbing payout behavior showed strong coupling to load-limiting thresholds, revealing notable parameter interdependencies. These results demonstrate that integrating pretensioners and load limiters into child restraint systems could yield meaningful safety benefits but must be optimized holistically to balance competing injury metrics. The study provides both empirical insight and a statistical framework for evaluating advanced restraint configurations in pediatric occupant simulations.
Khattak, Mohid Muneeb, Bendig, Colleen, Louden, Allison, Noll, Scott
A Study on the Injury Risk of Occupant with Different Head and Neck Rotating Postures under the Frontal Impact Sled Conditions2026-01-05744/7/2026
Drivers obtain road information through head and neck rotation. In order to study the influences of head and neck rotation posture on occupant injury in frontal impact scenario, the THUMS (Total Human Model for Safety) AM50 human body model with five different head and neck rotation postures but without active muscles was adopted to study the biomechanical injury responses of occupant under the frontal impact scenario at 56 km/h in this study. Firstly, the kinematic responses of total body and head acceleration curves at the center of gravity predicted by PMHS (Post Mortem Human Subject) and THUMS AM50 human model under the sled test conditions were compared to verify the simulation model for subsequent study. Then, the THUMS AM50 human model with standard occupant seating posture was adjusted to have five different head and neck rotation postures with 0°, ±20°, and ±40° rotation angle, respectively. Finally, a series of frontal impact sled with or without airbag simulations were conducted for each THUMS AM50 human model with different head and neck rotation postures. The simulation results showed that with the increasing of head and neck rotation angle, the neck injury risk was increased while the thoracic injury risk was decreased. Regardless of whether airbags were present or absent, the model prediction for the standard posture indicated a lower injury risk. And regardless of whether the head and neck posture changed, the airbag always could provide a certain protection in that posture.
Li, Dongqiang, jiang, Yejie, Tan, Chun, Li, Yanyan, Gong, Chuangye, Wu, Hequan, Jiang, Binhui
Injury Risk Analysis of Occupant with Different Lower Limb Postures under the Frontal Impact Sled Conditions2026-01-05724/7/2026
To investigate the characteristics of injuries sustained by occupant with different lower limb postures under the frontal impact sled conditions. Using the finite element method a series of simulation analyses were conducted on THUMS (Total Human Model for Safety) AM50 human body model with four different postures, including standing posture, lower limb bent at 100°, 90°, and crossed forward-backward, under the frontal impact scenario at 56 km/h in this study. The simulation results indicated that the overall injury risk predicted by the THUMS AM50 huma body model with lower limb crossed forward-backward was higher than that predicted by the model with other postures. The values of injury criteria including of HIC (Head Injury Criterion), head resultant acceleration, and thoracic VC (Viscous Criterion) predicted by the THUMS AM50 huma body model with lower limb crossed forward-backward were highest in these series simulations. Also, the biomechanical responses, including stress or strain of thoracic/abdominal organs, pelvic cortical bone and knee ligaments, predicted by the THUMS AM50 huma body model with lower limb crossed forward-backward was higher than these predicted by the model with other postures.
Li, Dongqiang, jiang, Yejie, Tan, Chun, Li, Yanyan, Li, Yihui, Wu, Hequan, Jiang, Binhui, Zhu, Feng
Vault-Induced Pitchover Crash Testing of a Recreational Off-Highway Vehicle (ROV)2026-01-05464/7/2026
Vehicle pitchover crashes can result in very severe accelerations and forces. Literature and test data available on pitchover crashes is sparse. This paper presents the results of a full-scale pitchover/rollover crash test using an instrumented vehicle in a controlled and documented off-road environment. The test vehicle was driven to the launch point by an off-board operator using remote steering and throttle controls. The test vehicle then experienced an airborne phase during which forward pitching occurred, followed by a front-to-ground impact which induced additional pitchover motion. Then, following the initial front and rear impacts, the vehicle transitioned from a pitchover to rollover motion before coming to rest. The resulting vehicle motion, vehicle damage markings, and ground markings were documented with various slow motion and real time camera views. The test vehicle was instrumented with accelerometers, rotation rate sensors, and other sensors, the results of which provide useful correlation with previously published test data. PC-Crash version 15.0.0.4a was used to analyze the pitchover test, and comparisons are derived between the real-world test and the motion calculated in the computer simulation. The PC-Crash program predicted launch speed to within 6% of the actual crash test. The results are useful for analysis and reconstruction of similar pitchover crashes.
Warner, Mark, Warner, Wyatt, Swensen, Grant, Perl, Mark
The Characterization of Longitudinal Lumbar Acceleration in Low-Speed Rear-End Impacts Across Different Surrogate Occupant Types2026-01-05524/7/2026
Longitudinal lumbar acceleration is often overlooked as a key variable when biomechanically assessing lumbar response in rear-end collisions. The objective of this study is twofold: (1) to conduct a comprehensive literature review of peak longitudinal lumbar acceleration to statistically evaluate differences between three surrogate occupant types: human volunteers, post-mortem human subjects (PMHS), and anthropomorphic test devices (ATDs) and (2) to construct a mathematical predictive model of longitudinal lumbar acceleration using peak longitudinal vehicle or sled change in velocity (delta-V) and vehicle acceleration in rear-end impacts. Peak longitudinal lumbar acceleration was obtained from peer-reviewed literature and the Insurance Institute for Highway Safety database. Tests included belted human volunteers, PMHS, and ATD occupants seated upright in unmodified, conventional driver seats. Compared to human volunteers instrumented at L5-S1, BioRID ATDs instrumented at L1 displayed greater ratios of longitudinal lumbar acceleration to delta-V, but lower ratios when normalized by vehicle acceleration. Accelerometer placement, crash severity, test configuration and pulse duration across surrogate occupant types were found to influence overall lumbar response, relative to vehicle acceleration and delta-V. Regressions for human volunteers indicated positive relationships for longitudinal lumbar acceleration with respect to vehicle acceleration (R2 = 0.93, p<0.001) and all surrogate occupant types for vehicle delta-V (R2 = 0.96, p<0.001). Longitudinal lumbar acceleration was highly correlated to vehicle delta-V in both human volunteers and BioRID ATDs and was sensitive to crash severity and vehicle crash parameter choice (vehicle acceleration vs. delta-V). Close alignment was found between L1 BioRID ATD and L5-S1 human volunteer longitudinal accelerations at vehicle delta-Vs ≤ 14.3 km/h, suggesting that BioRID ATDs at L1 can reasonably replicate human lumbar response at L5-S1 within this crash severity range. This study quantified differences in longitudinal lumbar acceleration across occupant types in rear-end collisions and developed surrogate-specific and cumulative models for prediction of longitudinal lumbar acceleration from delta-V.
Zambare, Keya, Ogbu Felix, Jordan, Arana Barcala, Emily, Westrom, Clyde, Caraan, John, Adanty, Kevin, Shimada, Sean
Development of a Tire Blowout Experimental Platform for Dynamics and Control Validation2026-01-02024/7/2026
Tires are critical to vehicle dynamics, transmitting traction, braking, and cornering forces to the road. A tire blowout, the sudden and rapid loss of inflation pressure due to puncture or structural failure, can cause severe instability, rollover, or collisions. Understanding vehicle response during blowout events is essential for developing robust safety systems and control strategies. Earlier developed simulation models are used to study and understand vehicle behavior during blowouts, but there is a lack of on-road testing platforms to validate these models experimentally. In this paper, an experimental platform integrating a tire blowout device and an instrumentation system has been developed to address this gap. The blowout device consists of multiple solenoid valves mounted on the wheel surface and powered by a 12V power supply. All valves can be triggered at the same time using an RF remote, producing rapid and synchronized deflation. As an extension of this implementation, an Arduino-based actuation system is being developed for individual valve actuation and custom deflation profiles. The instrumentation system includes GNSS, IMU, and CAN-based data acquisition for vehicle dynamic variables. Furthermore, outriggers will be installed on the vehicle to ensure safety during testing. Unlike prior devices that use single valves with external pneumatic hoses and laboratory-only operation, the proposed platform is compact, lightweight, and field-deployable due to its integration of multi-valve actuation, custom deflation control, outrigger-based safety measures, and instrumentation. The developed platform enables safe, repeatable, and full-scale on-road blowout testing within required timeframes, providing a novel framework that bridges simulation and real-world validation.
Kanthala, Maha Vishnu Vardhan Reddy, Krishnakumar, Ashwin, Lin, Wen-Chiao, Chen, Yan
Occupant and Seat Responses in Various Moderate- to High-Speed Rear Impact Conditions: Focus on Head-to-Head Restraint Interactions2026-01-05654/7/2026
Head restraint requirements and designs have evolved to minimize the delay in head support and reduce differential loading in the neck. As a result, they have become bigger, closer to the occupant’s head, and angled forward relative to the seat back. Head restraints have been found missing or detached in the field; they may be removed pre-crash due to occupant comfort issues, or post-crash for better accessibility during extrication. Additionally, although rare, head restraints may become detached in severe rear impacts due to occupant loading. To better understand occupant-to-head restraint dynamic interactions, nine rear sled tests were conducted. The test conditions were selected to represent worst case severe loading scenarios. An instrumented 50th Hybrid III ATD (Anthropomorphic Test Device) was lap-shoulder belted on a right-front seat. The neck was equipped with a bracket and lower neck load cell designed for rear impacts. Three series of sled tests were performed wherein the kinematics and kinetics of a restrained ATD were compared across 3 seat configurations: a conventional modern seat, a rigidized modern seat, and an ABTS (all-belts-to seat). Occupant postures evaluated included seated nominally and leaning forward, as may occur in response to hard pre-impact braking and/or an initial frontal impact. Two crash severities were evaluated including a moderate speed (24 km/h delta V pulse based on Euro NCAP) and a very high-speed (49 km/h delta V) condition. Within each series, the sled pulse and ATD initial posture were held constant. The first series (Match #1) was conducted at 24 km/h with a leaned occupant. All biomechanical responses were below IARVs (Injury Assessment Reference Values). The highest responses relative to IARV were for upper and lower neck tension and extension. The Nij was greatest with the ABTS seat for upper neck and with the rigidized seat for lower neck, highlighting the importance of using both the upper neck and lower neck instrumentation. The second series (Match #2) was at 49 km/h with the nominally seated ATD, and the third (Match #3) was at 49 km/h with a leaning forward ATD. The biomechanical responses were below IARV when nominally seated. The biomechanical responses of Match #2 were more favourable than Match #3, highlighting the benefits of early energy absorption during the ride-down. For example, the upper neck Nij was 2.4 in the conventional seat, 4.2 in the rigidized seat and 5.1 in the ABTS. The corresponding lower neck Nij was 4.2, 5.5 and 2.3. The normalized chest 3 ms response was greatest in the rigidized seat, followed by the ABTS, irrespective of sitting posture. There are numerous reasons for an occupant to be out of position prior to a rear impact. In this study, the test conditions were selected to assess head-to-head restraint interactions in severe conditions, including leaning forward. Though the head restraints remained attached in all tests, the results provide insight on the seat and head restraint performance, and head and shoulder loading characteristics, in particular in some non-nominal postures.
Parenteau, Chantal, Burnett, Roger, Davidson, Russell
Sideswipe Impact Severity Testing and Analysis with an Instrumented Hybrid III Anthropomorphic Test Device (ATD)2026-01-05324/7/2026
Vehicle-to-vehicle sideswipe collisions are unique in their impact characteristics because the vehicles typically do not reach a common velocity at impact. To better understand the characteristics and dynamics of sideswipe collisions, vehicle-to-vehicle crash testing was performed to find the relationships between variables related to the impact, such as closing speed, relative angle, and overlap depth. This paper discusses data collected for three sideswipe (oblique) impact tests conducted at a testing facility in Buffalo, New York. The tests were conducted using a passenger vehicle as the sideswiping vehicle, which impacted a stationary cargo van. The passenger vehicle was towed into the van at relative angles ranging from 8 to 15 degrees and at velocities of 5 to 20 mph. Two different (but identical) passenger cars and two cargo vans were used during the testing series. Test results were then utilized to investigate a methodology of analyzing sideswipe collisions as a combination of low-speed lateral impact in conjunction with longitudinal sliding friction for application to accident reconstruction. One instrumented Hybrid III 5th percentile female Anthropomorphic Test Device (ATD) outfitted with a 15 pound weighted vest was placed in the front driver designated seating position according to instructions specified in the TP-208 Test Procedure. TP-208 is the USDOT laboratory test procedure for FMVSS 208, Occupant Crash Protection. The testing facility performed all acquisition, setup, and instrumentation operations for the vehicles utilized in crash testing, as well as provided the reported data obtained during testing. For testing, the ATD and test vehicles were instrumented with accelerometers, which were used to record the accelerations to the occupant and vehicles throughout each sideswipe impact test. The ATD was additionally instrumented with force transducers to measure the forces experienced by the ATD during the testing. The objective of this research was to examine the collision dynamics and the instrumented ATD responses for each sideswipe test performed to provide data relevant to accident reconstruction and biomechanical analysis. The research also compared the collected test data to a proposed methodology for reconstructing sideswipe collisions.
Danaher, David, McDonough, Sean, Donaldson, Andrew, Neale, William, Cochran, Reece
Multi-Physics Topology Optimization and Neural Network–Based Design of Experiments for Lightweight Automotive Cast Components2026-01-05104/7/2026
This paper presents a hybrid optimization framework that integrates Multi-Physics Topology Optimization (MPTO) with a Neural Network–surrogated Design of Experiments (NN-DOE) to enable lightweight structural design while satisfying crashworthiness, durability, and noise, vibration, and harshness (NVH) requirements under practical casting and packaging constraints. In the proposed MPTO formulation, crash and durability performances are incorporated through equivalent static compliance measures, while NVH performance is assessed using a frequency-domain dynamic stiffness metric, allowing consistent evaluation of trade-offs among competing design requirements. The framework is first demonstrated using a mass-produced passenger-car lower control arm (LCA) as a benchmark component. In this application, MPTO achieves weight reduction under multi-physics objectives by removing non-load-bearing material. Results show that single-discipline optimization produces unbalanced topologies, while balanced crash–durability–NVH consideration yields robust load paths. The study further demonstrates that crash and durability are dominated by static compliance–based response, whereas NVH performance is governed by frequency-dependent dynamic response over the relevant frequency range. The framework is then applied to a front engine mounting bracket of a newly developed heavy-duty truck. In this second application, a two-step strategy is employed in which MPTO first establishes the global load-carrying topology under manufacturing and packaging constraints, followed by NN-DOE–based local refinement to achieve stress attenuation at non-designable regions through global structural stiffness rebalancing, rather than direct geometric modification. Final verification confirms a steel-to-aluminum material transition achieving approximately 45% weight reduction and a substantial improvement in durability fatigue life, while maintaining required crash performance.
Kim, Hyosig, Senkowski, Andres, Gona, Kiran, Saroha, Lalit, Boraiah, Mahesh
Safety Monitor for Off-Road Planning with Uncertainty Bounded Bekker Costs2026-01-01414/7/2026
Reliable off-road autonomy requires operational constraints so that behavior stays predictable and safe when soil strength is uncertain. This paper presents a runtime assurance safety monitor that collaborates with any planner and uses a Bekker-based cost model with bounded uncertainty. The monitor builds an upper confidence traversal cost from a lightweight pressure sinkage model identified in field tests and checks each planned motion against two limits: maximum sinkage and rollover margin. If the risk of crossing either limit is too high, the monitor switches to a certified fallback that reduces vehicle speed, increases standoff from soft ground, or stops on firmer soil. This separation lets the planner focus on efficiency while the monitor keeps the vehicle within clear safety limits on board. Wheel geometry, wheel load estimate, and a soil raster serve as inputs, which tie safety directly to vehicle design and let the monitor set clear limits on speed, curvature, and stopping at run time. The method carries uncertainty analytically into the upper confidence cost and applies simple intervention rules. Tuning of the sinkage limit, rollover margin, and risk window trades efficiency for caution while keeping the monitor light enough for embedded processors. Results from a simulation environment spanning loam to sand include intervention rates, violation probability, and path efficiency relative to the nominal plan, and a benchtop static loading check provides initial empirical validation.
Naik, Akshay, Norris, William, Sreenivas, Ramavarapu S., Soylemezoglu, Ahmet, Nottage, Dustin S., Patterson, Albert
Effects of Obstacle Height and Vehicle Roll Behavior on Electric Vehicle Side Impact Safety2026-01-04054/7/2026
Electric vehicles (EVs) face unique safety challenges under pole side impact conditions, largely due to the presence of floor-mounted battery packs. Existing regulatory test procedures, such as FMVSS 214, primarily address occupant injury using full-height cylindrical obstacles. These procedures were originally developed for internal combustion vehicles (ICVs). However, real-world roadside crashes frequently involve obstacles of varying heights, such as guardrails, curbs, and median bases. While these obstacles pose limited risk to the passenger compartment, they can intrude into the battery pack and trigger thermal runaway. This study investigates the influence of obstacle height on EV pole side impacts. Finite element simulations of a commercially available sedan were conducted against rigid obstacles of different heights. Results reveal a non-monotonic trend of battery intrusion governed by the interplay between rollover dynamics and structural stiffness. Theoretical analyses were conducted to clarify the underlying mechanisms. When the obstacle height falls below the window frame level, rollover effects become more significant. The longer roll moment arm allows part of the impact energy to be dissipated through vehicle roll motion, leading to a reduction in battery intrusion. However, as the obstacle height is further reduced into the threshold beam and battery side beam region, the supporting structural members are bypassed. The equivalent contact stiffness drops sharply, resulting in significant battery intrusion. The findings demonstrate that obstacle height governs EV battery safety through a competition between rollover energy dissipation and reduced contact stiffness. This work provides new insights for extending existing side impact tests to low-height obstacles and offers guidance for vehicle safety design.
Ma, Chenghao, Xing, Bobin, Zhou, Qing, Xia, Yong
Numerical Investigation on Thorax Rib Deflections of 50th Male in Vehicle Side Oblique Pole Impact Using Human Body Model2026-01-05664/7/2026
The WorldSID-50M dummy is widely adopted in regulatory and third-party testing programs (e.g., ECE, Euro-NCAP, C-NCAP) owing to its advanced design and superior biofidelity. However, in vehicle side oblique pole crash tests involving shoulder-covered side airbags - an expanded testing modality - excessive deflection of the upper thoracic ribs was observed. Notably, this phenomenon was absent in standard side moving deformable barrier (SMDB) tests. This study pursued two core objectives: (1) to systematically document the excessive upper thoracic rib deflection of the WorldSID-50M dummy in side oblique pole crash tests; and (2) to investigate the influence of arm-thorax interaction on such deflection using a Human Body Model (HBM) representative of a 50th percentile male occupant. Numerical simulation results reveal that while arm-thorax interaction does contribute to rib deflection, its impact on the excessive deflection of the upper thoracic ribs is negligible.
Zhou, DY, Chen, Shaopeng, Yan, Li, Wu, Jing, Liu, Chong, Lv, Xiaojiang, Yang, Heping
Revisiting Rear Seat Safety: Field Evaluations of Relative Injury Risk Across Seating Positions and the Integration of Advanced Rear Seat Belt Systems2026-01-05614/7/2026
Despite advances in crash avoidance, occupant restraint systems remain crucial in protecting the motoring public. Following decades of improvement in occupant protection, including several supplemental restraint systems for front seat occupants, the safety of rear seat occupants has recently undergone scrutiny. Studies evaluating rear seat occupant injury risk via field crash data have reported reduced relative safety in rear seating positions and alluded to advanced rear seat restraints, such as pretensioners and load limiters, as potential solutions. While the pursuit of novel technologies has historically improved occupant outcomes, evaluation of new systems in both controlled laboratory environments and field crashes is necessary to understand potential consequences of widespread introduction. This study analyzed the prevalence of advanced seat belts (load limiters and pretensioners) in the rear seating positions in the U.S. fleet. Additionally, occupant injury risk was compared across vehicles equipped with conventional and advanced seat belts in the rear seat, as well as between rear and front seat occupants, using data from state crash databases. The proportion of vehicles equipped with advanced rear seat restraints has steadily increased over the past couple of decades, but, as of 2023, remained below 10% of registered vehicles on US roadways. Evaluation of police-reported field crash data indicated that lap-shoulder belted rear seat occupants sustained fatal or incapacitating injury at a lesser rate than front seat occupants. Rear seat occupants have historically been and remain well-protected. Current field data do not consistently demonstrate a statistically significant reduction in rear seat occupant injury or fatality risk attributable to advanced seat belts. However, the relatively low number of crashes involving serious injury or fatality for rear-seated occupants in vehicles equipped with these systems underscores the need for additional data to fully evaluate their effectiveness in real-world crashes.
Rapp van Roden, Elizabeth Ann, Miller, Bruce, Pearson, Joseph, Williamson, James, Brown, Thomas
Effects of Child Anthropometry, Seatback Angle, Seat Rotation Angle, Seatbelt Force Limiting, and Collision Type on Injury Risk of Child Occupants in Highly Automated Vehicles2026-01-05704/7/2026
This study aimed to evaluate the influence of child anthropometry, seating postures (recline and rotation), seatbelt force limiting, and frontal collision scenarios on the kinematic response and injury risk in highly automated vehicles. The TUST IBMs 6YO-O model was conducted the frontal collisions in sled tests. This simulation matrix includes five percentiles six-year-old occupants (P3, P25, P50, P75, and P97), three seatback angles (20°, 30°, and 45°), four seat rotation angles (0°, 90°, 180°, and 270°), three seatbelt force limiting (2.6 kN, 3.6 kN, and 4.6 kN), and three frontal collision types. Injury risks were assessed including the child occupant's head, neck, chest/abdomen, and lumbar region in each simulation (n=540). The results indicate that the child anthropometry, the seatback angle, and the seat rotation angle have a significant influence on the motion responses. Statistically significant differences between all the groups within each independent variable category were observed based on the analysis of variance. As the child dimension increases, the risk of head injury decreases showing by HIC15, while the risk of neck and lumbar injuries increases. As the seatback angle increases, biomechanical parameters of the head show an increasing trend. The risk of upper neck injury decreases, while the risk of lumbar injury decreases and then increases. As the seat rotation angle increases, the risks of head, neck, and chest injuries initially rise and subsequently decrease, while the risk of lumbar injury demonstrates a downward trend. Seatbelt force limiting exhibited a positive correlation with head, neck, and lumbar injury risks. Consequently, small percentile child experiences higher head loads in smart cockpits, with seatback angle and seat rotation angle being key factors contributing to child injuries. These findings highlight the critical need to address the vulnerability of smaller children in smart cockpits by adapting integrated active and passive safety systems to mitigate their injury risk.
Wang, Yanxin, Zhao, Hongqian, Li, Haiyan, He, Lijuan, Cui, Shihai, Lv, Wenle
Machine Learning Based Meta-Analysis of IIHS Moderate Overlap Frontal Crash Test for Rear Seat Occupant Safety Performance2026-01-05794/7/2026
A machine learning (ML)-based meta-analysis was conducted to evaluate rear seat occupant safety performance in the Insurance Institute for Highway Safety (IIHS) Moderate Overlap Frontal (MOF) 2.0 crash test. ML models were trained on historical IIHS crash test data to predict rear passenger injury metrics using vehicle architecture, restraint system characteristics, crash pulse parameters, and vehicle kinematics as input features. The models demonstrated high predictive accuracy and were subsequently used in a Sobol sensitivity analysis to identify critical design parameters influencing injury outcomes. The analysis revealed that rear passenger injury metrics were most sensitive to restraint system parameters. Specifically, crash pulse magnitude was the dominant factor for head injury metrics, pretensioner activation time for neck tension force, and lap belt force for the Neck Injury Criterion (Nij). For chest-related metrics—sternum deflection, dynamic belt position, and maximum belt position—the initial belt position emerged as the most influential factor. This study demonstrates the potential of ML models to uncover dominant injury mechanisms and critical design parameters without explicitly encoding biomechanical knowledge. The findings also offer actionable insights to guide future vehicle safety design improvements for rear seat occupants.
Lalwala, Mitesh, Kim, Wonhee, Furton, Lisa, Song, Jay
High Biofidelity Modification of Thoracolumbar Structure in THOR Model for Reclined Occupant2026-01-01964/7/2026
With the rapid development of automated driving and the increasing adoption of “zero-gravity” seats, the crash safety of highly reclined occupants has become a critical issue. The current THOR dummy, designed for frontal impacts in the standard upright posture, exhibits limitations when directly applied to reclined seating configurations, including insufficient spinal flexion capability and excessive posterior pelvic rotation. In this study, the thoracolumbar spine kinematics of the THUMS human body model, reconstructed against post-mortem human subject (PMHS) tests, were analyzed. A two-segment linear fitting was employed to characterize a “dummy-like” spinal flexion response, yielding a virtual rotational hinge located near the thoracolumbar joint of the original THOR model. The characteristic rotation angle obtained from THUMS showed a strong linear correlation with the flexion moment of the T12–L1 vertebrae. Based on this relationship, the rotational joint of the THOR dummy was unlocked during impact and assigned a torsional stiffness of 600 Nm/rad. Additional modifications were implemented in the hip region to enhance model applicability. Comparative simulations demonstrated that the modified THOR model achieved closer agreement with PMHS responses than both the Hybrid III and the baseline open-source THOR models. In particular, the posterior pelvic tilt was reduced from approximately 20° in the baseline THOR to about 10° in the modified version. These results indicate that incorporating PMHS-based thoracolumbar flexion characteristics together with targeted hip modifications significantly improves the biofidelity of the THOR dummy for reclined-occupant crash scenarios, providing a solid foundation for future dummy development and safety assessment.
Guo, Wencheng, Kuang, Gaoyuan, Shen, Wenxuan, Tan, Puyuan, Zhou, Qing
Novel Tube-in-Tube Steel Side Sill Reinforcement Design and Validation for Enhanced Crash Performance in EVs2026-01-04784/7/2026
Increased use of Electrical vehicles (EVs) brings in unique structural design challenges particularly in Side Impact scenarios when the battery pack positioned near the sill region elevates the possibility of battery penetration and thermal runway in crash event. Thus, Electric Vehicles require unique structural design solutions. This study focuses on a novel steel tube-in-tube Side Sill reinforcement design and its performance benefits over a traditional aluminum Side Sill reinforcement commonly used for battery protection in EV vehicles body components. The proposed Steel Side Sill design layout mainly focuses on structural rigidity and improved load transfer during side pole impact crash cases and addressing manufacturing complexity and cost reduction opportunity. Multiple Steel Side Sill reinforcement design iterations are carried out by finite element analysis with software like LSDYNA Hyper works [1]. The goal was to develop an optimal tubular design - maximizing load transfer and energy absorption. The study was mainly divided into two stages, 1) CAE Full Vehicle and Component; 2) Component Test Validation. Initial design parameters were derived based on full vehicle and component CAE and then the design was validated using physical testing. The results show that the tube- in-tube Side Sill reinforcement structure has similar performance compared to base Aluminum design and indicated possibility of reduced manufacturing complexity, cost and mass saving options. These findings proved that the proposed novel Side Sill reinforcement in EV specific body in white (BIW) is helpful to design safer vehicles and effectively meet both regulatory and consumer matrix.
Kusnoorkar, Harsha, Khutorsky, Alex, Penumetsa, Vivek, Koraddi, Basavaraj
Pre-Crash Scenario Analysis and Generation for Integrated Safety System Virtual Testing with Real Accident Data2026-01-00624/7/2026
Integrated active and passive safety protection systems have made substantial contributions to reducing traffic accidents and mitigating human injuries. However, assessing such systems through vehicle collision tests is limited, as this approach cannot cover the wide range of accident scenarios. To address this gap, identifying and generating representative pre-crash scenarios from real-world accidents provides key boundary conditions for the setup of virtual test scenarios. In this study, we used the Future Mobile Traffic Accident Scenario Study (FASS) dataset to reconstruct 112 two-wheeler accidents. For each case, we extracted pre-crash dynamic information, static attributes, and environmental context. An autoencoder was employed to encode high-dimensional features of scenarios, and K-means clustering was applied to categorize the accidents into eight representative pre-crash scenarios. For each scenario, we examined the motion states of participants and further compared the behaviors and injuries between motorcycle and bicycle accidents. The results show that motorcycles have a higher average pre-crash speed than bicycles (22.4 vs 16.2 km/h), resulting in a greater proportion of Maximum Abbreviated Injury Scale (MAIS) 4+ cases (35.6% vs 18.9%). Furthermore, a Gaussian Mixture Model was applied to fit the scenario features. This model was then used to randomly generate the initial conditions of pre-crash scenarios, including the positions, speeds, and yaw angles of vehicles and two-wheelers. The proposed scenario generation method was first applied to pre-crash scenario construction for integrated safety systems tests, and it can create diverse, statistically grounded scenarios that reflect real-world accident distributions. These scenarios can broaden the test scope of integrated safety systems and support their implementation.
Wang, Guojie, Gao, Xin, Liu, Siyuan, Liu, Jiaxin, Li, Quan, Shi, Liangliang, Nie, Bingbing
Design and Simulation Analysis of an Integrated Honeycomb-Filled Front Bumper for a Special Vehicle2026-01-04754/7/2026
In frontal collisions of automobiles, the bumper beam at the front of the vehicle plays a crucial role in absorbing energy and protecting the vehicle body during a collision. To enhance the collision resistance of a specific type of special vehicle with a non-load-bearing body structure, this paper focuses on this type of vehicle and conducts a study on the design and collision performance of an integrated vehicle front bumper - anti-collision beam structure based on aluminum alloy additive manufacturing technology. A novel bumper structure is proposed, which integrates the front bumper and the front anti-collision beam of the vehicle and is integrally formed using aluminum alloy additive manufacturing technology. This integrated structure is directly connected to the vehicle frame. Firstly, based on the appearance of the special vehicle body and the form of the front anti-collision beam of traditional passenger vehicles, an integrated design of the vehicle front bumper- anti-collision beam structure is carried out and connected to the vehicle body. Subsequently, based on the previous bumper design, a honeycomb structure is introduced internally, and the introduced honeycomb structure is integrally formed with the front bumper. Finally, finite element simulation analysis of two types of frontal bumper collisions under the same collision conditions is conducted. The results show that the initial integrated front bumper can achieve basic anti-collision beam functions, while the front bumper with a honeycomb composite structure can improve the transmission path of collision force, ensure stable deformation, significantly enhance the energy absorbed during a collision, and increase the specific energy absorption, indicating that the integrated honeycomb-filled front bumper can effectively enhance the collision resistance of special vehicles.
王, Xufan, Yuan, Liu-Kai, Zhang, Tangyun, Wang, Tao, Zhang, Ming, Wang, Liangmo
Evaluating the Effects of Improper Positioning and Unbuckling of a Restraint System on a 10-Year-Old Child ATD in a Far Side Side-Impact Environment2026-01-05624/7/2026
Five sled tests were performed with a Hybrid III (H-III) 10-year-old child sized Anthropomorphic Test Device (ATD) positioned in the 2nd row left seat of a three row 2006 Sport Utility Vehicle (SUV). A HYGE Sled buck was positioned to represent/replicate a side impact collision to the passenger (right) side of the SUV, with a Principal Direction of Force (PDOF) of 60 degrees, resulting in a far side side-impact for the ATD. Of the 5 tests performed, three of the five tests were performed with a delta-V of 17 mph, and two of the tests at a delta-V of 24 mph. Of the 17 mph tests, one test was performed with a properly restrained ATD, and two tests performed with improper restraint positioning. Both of the 24 mph tests were performed with improper restraint positioning, effectively identical to the two 17 mph delta-V tests. The two improper restraint use tests (at both 17 and 24 mph delta-V) included two different improper restraint scenarios. The first scenario of improper restraint positioning involved moving the torso belt from the left shoulder, over the head, and onto the right shoulder. The second scenario involved the same belt re-positioning as the first scenario, but additionally a disengaged latch plate from the buckle, essentially creating a condition of seat belt entanglement. Each of the five tests utilized its own salvage-vehicle-harvested seat belt assembly, originating from the same model series of SUV. All tests were documented with 4 high-speed video cameras. Occupant kinematics and seat belt physical evidence were analyzed and compared across the test series. Head accelerations and upper neck loads were also evaluated. The results demonstrated the uniqueness of physical evidence left behind on components of the seat belt system, both in terms of locations of the evidence as well as the extent and geometric orientation of the evidence, across the three demonstrated scenarios (proper, improper, and improper and unbuckled). Additionally, the three scenarios exhibited significant differences with respect to the head accelerations and neck loads experienced by the ATD.
Luepke, Peter, Hewett, Natalie, Betts, Kevin, Van Arsdell, William, Weber, Paul, Stankewich, Charles, Miller, Gregory, Watson, Richard, Sochor, Mark
Inertial Pedal Displacement and Brake Switch Activation in Frontal Crash Events2026-01-05414/7/2026
This paper presents research into the inertial displacement of brake pedals and the subsequent activation of brake light switches during crash events. In certain scenarios, such as multiple-impact crashes or crashes with pre-impact interactions such as curb strikes or sideswipes, inertial forces alone may generate sufficient brake pedal movement to trigger the brake switch, activating the brake lights. Such signals may be recorded by an Event Data Recorder (EDR) or observed by witnesses and incorrectly interpreted as an indication of intentional driver braking. To investigate this phenomenon, HYGE sled tests were performed using brake pedal assemblies and associated components from a Toyota Tacoma pickup truck and a Cadillac DeVille passenger sedan. The assemblies were subjected to acceleration pulses simulating a frontal impact, with high-speed video used to capture brake pedal displacement and brake light activation. The tests demonstrated that inertial loading from a pulse with a delta-V (change in velocity) as low as 12 mph could result in momentary brake light activation due to pedal displacement from inertial forces. Increasing the magnitude of the acceleration pulse produced greater displacement of the brake pedal and extended the duration of the brake light activation. An example is presented that demonstrates inertial pedal movement in a full-scale vehicle test conducted by striking a curb, which resulted in brake light activation with a delta-V considerably less than 12 mph. Additionally, a field survey of 50 passenger vehicles found that the brake switch activation threshold ranged from 0.25 to 0.56 inches of pedal travel for 80% of the vehicles measured. These findings indicate that relatively small crash accelerations and durations can produce sufficient inertial pedal movement to activate brake lights and that only minimal pedal displacement is required in most vehicles.
Walker, James, Duran, Amanda, Barnes, Daniel, Osterhout, Aaron, Clayton, Aidan
Low Speed Bumper System Impact Variation Study2026-01-04744/7/2026
Variation studies are an important part of the product development process. They help to understand and estimate real-world deviation from nominal design parameters, optimize designs for robustness, reliability, and cost-efficiency. CAE and Virtual tools enable us to simulate variation types and capture the full bandwidth of actual field performance- rather than the validation from a limited number of physical tests. In this study, the effects of various factors on vehicle performance during low-speed impacts, utilizing a Design of Experiments (DOE) approach have been investigated through virtual simulation. Low-speed impacts, typically defined as collisions occurring at speeds less than 2.5 mph, are critical for understanding vehicle insurability and compliance with regulatory standards. The factors examined include vehicle impactor position, impact speed, angle of collision, part thickness variation, material property variation. The DOE methodology allowed for a systematic analysis of these variables and their interactions, providing a comprehensive understanding of their influence on vehicle deformation while minimizing the number of iterations. Results indicate that impact speed significantly affects the extent of deformation, along with thickness of the material variance. These findings are essential for optimizing vehicle design to enhance resistance to damage in low-speed collisions and ensure compliance with regulatory requirements. The study underscores the importance of considering multiple factors and their interactions in vehicle low speed testing to develop a robust virtual performance prediction methodology under front or rear impact loading.
Suravaram, Raghu Mohan Reddy, Islam, ABM Iftekharul, Larson, John, Tehrani, Babak, Koch, Lisa, Mathur, Mohit Sain
Use Inertial Sliding of Reclined Seat to Enhance Occupant Retention under Rear-End Crash2026-01-05634/7/2026
Autonomous vehicles may attract more passengers to recline their seat for comfort. However, under severe rear-end crashes and large reclining angle, the backward inertia could completely throw occupant out of seat. Even if the occupant body can be restrained by seatbelt, the occupant’s head could slide out of the head restraint area. Any of these situations may cause severe injuries. To address this safety concern, we developed a sliding seat system designed to enhance occupant retention. Activated by impact inertia of rear-end collision, the system allows the seat sliding backward along its track in a controlled manner, and the sliding stroke is accompanied by a restraint force and absorbs some amount of kinetic energy during the sliding. Thus, occupant retention can be enhanced, and injury risks of head and neck can be reduced. To demonstrate this concept, we built a MADYMO model and conducted a parametric analysis. The model includes a 50th percentile human model, a vehicle seat, and a seat-mounted three-point seatbelt. Under 50 km/h rear-impact load, we evaluated occupant kinematics and critical injury metrics of 45o reclined posture. The relative displacement between occupant pelvis and seatback was used to measure the distance that occupant slides backward, which is a metric for occupant retention. The results have shown that seat sliding distance is the most critical factor for occupant retention, and the longer the sliding distance, the greater the retention effect and the lower the injury risk. In a typical scenario when 200 mm of sliding distance is available for sliding, compared to traditional fixed seat (no sliding allowed), the occupant displacement is reduced by 45%, the Head Injury Criterion value is reduced by 55%, and the Neck Injury Criterion value is decreased by 66%. For vehicle seat design, using the sliding seat system may help off-load the burden of enhancing recliner stiffness, a critical component for maintaining seatback stiffness level in rear-end collisions.
Dai, Rui, Zhou, Qing, Puyuan, Tan, Shen, Wenxuan
Development of Automotive Hood Using Multi-Material Double Injection Molding – An Overview2026-01-04764/7/2026
This paper presents the multidisciplinary development of a hybrid automotive hood manufactured using double-shot injection molding with overmolded brackets. Conventional steel and aluminum hoods, while structurally reliable, pose challenges in terms of weight reduction, pedestrian head protection, and manufacturing cost. Composite and thermoplastic alternatives supported by computational analysis and advanced molding processes provide opportunities to address these challenges. Finite element analysis (FEA) was employed to evaluate torsional and bending stiffness, locking load, and crashworthiness, while pedestrian headform simulations following ECE R127 and EEVC WG17 guidelines were conducted to assess compliance with safety regulations. Adhesion and bonding strength of overmolded polymer–polymer interfaces were studied to validate manufacturing feasibility. Results confirm that hybrid hoods fabricated using multi-material double-shot molding can achieve weight reductions of up to 30% compared with steel, maintain structural stiffness equivalent to aluminum, meet head injury criterion (HIC) thresholds, and reduce assembly complexity by consolidating brackets and reinforcements into a single integrated structure.
Ganesan, Karthikeyan, Seok, Sang Ho, Jo, Hyoung Han
Terminology and Measurement Methodology for Determining Vehicle Overlap in Offset-Frontal CrashesJ3227_202604 (Current)4/1/2026
This SAE Information Report establishes procedures and terminology for measuring, calculating, and referencing the percent vehicle overlap for a case vehicle in real-world or staged end plane collisions where the end plane of the case vehicle is engaged at one of the two bumper corners but not both. This SAE Information Report may be applied to rear or front plane impacts.
Crash Data Collection and Analysis Standards Committee
From Stoplights to On-Ramps: A Comprehensive Set of Crash Rate Benchmarks for Freeway and Surface Street ADS Evaluation09-14-02-00033/31/2026
This article presents crash rate benchmarks for evaluating US-based automated driving systems (ADSs) for multiple urban areas, distinguishing between freeway and surface street crash rates, and breaking them down by crash severity and type. The purpose of this study was to extend prior benchmarks focused only on surface streets to additionally capture freeway crash risk for future ADS safety performance assessments. Using publicly available police-reported crash and vehicle miles traveled (VMT) data from Arizona, California, Georgia, and Texas, the methodology details the isolation of in-transport passenger vehicles, road type classification, and crash typology. Key findings revealed that freeway crash rates exhibit large geographic dependence variations with any-injury-reported crash rates being approximately three times higher in Atlanta (2.3 IPMM; the highest) when compared to San Diego (0.7 IPMM; the lowest). The results show the critical need for location-specific benchmarks to avoid biased safety evaluations and provide insights into the VMT required to achieve statistical significance for various safety impact levels. The distribution of crash types depended on the outcome severity level. Higher severity outcomes (e.g., fatal crashes) had a larger proportion of single-vehicle, vulnerable road users (VRUs) and opposite-direction collisions compared to lower severity (police-reported) crashes. Given heterogeneity in crash types by severity, performance in low-severity scenarios may not be predictive of high-severity outcomes. These benchmarks are additionally used to quantify at the required mileage to show statistically significant deviations from human performance. Future work investigating the underlying factors influencing crash rates in each geographical area will further enhance future benchmarking efforts (by identifying potential confounders to account for when matching exposure between baseline and ADS data). This is the first article to generate freeway-specific benchmarks for ADS evaluation and provides a foundational framework for future ADS benchmarking by evaluators and developers.
Scanlon, John M., McMurry, Timothy L., Chen, Yin-Hsiu, Kusano, Kristofer D., Victor, Trent
Analysis and Determination the Time to Rollover of Tractor Semi-Trailer Vehicle Based on Multi-body System Analysis and Newton–Euler Equations02-19-03-00133/27/2026
This article aims to determine the time to rollover (TTR) of a tractor semi-trailer vehicle (TSTV). It uses a full dynamics model for assessment, specifically applying multi-body system analysis and Newton–Euler Equations with a nonlinear tire model. The model is applied to investigate velocities ranging from 40 km/h to 80 km/h and magnitude of steering angles ranging from 12.5° to 300°. The times at which the Load Transfer Ratio (LTR), Roll Safety Factor (RSF), and lateral acceleration reach their maximum values are evaluated. The survey results demonstrate the impact of velocity and steering wheel angle on the time it takes for the LTR, RSF, and lateral acceleration to reach their maximum values. The time interval between the RSF reaching 1 and the LTR reaching 1 range from 0.144 s to 0.655 s. Similarly, the time it takes for the tractor body’s lateral acceleration to peak and the LTR to reach 1 varies between 0.228 s and 1.555 s. Additionally, the time interval from when the semi-trailer body’s lateral acceleration reaches its maximum value to when the LTR reaches 1 range from 0.057 s to 1.155 s. These time intervals can be used to determine the reserve time for early warning or control systems when selecting the thresholds, based on the vehicle’s lateral acceleration during a turn.
Hung, Ta Tuan, Khanh, Duong Ngoc
Anti-Rollover Strategy for Six-Axis Semi-Trailer Based on Lateral Force Balance02-19-04-00242/24/2026
To address the rollover risk of six-axle semi-trailers due to their large mass, high center of gravity, and multi-axle articulation, a lateral force balance anti-rollover strategy based on the Ackermann steering principle is proposed. By establishing the wheel angle constraint equations for the full-wheel steering system of the six-axle semi-trailer, a rigid-body dynamic model considering the articulation characteristics is developed. The key control and observation parameters are included in the wheel angles, center of gravity lateral offset, yaw angular velocity, sideslip angle, and lateral load transfer rate. An SMC-PID joint controller is designed, in which the third axle steering angle of the tractor is optimized by the SMC controller, and the trailer’s three-axle steering angle tracking control is achieved by the PID controller. The nonlinear accumulation of centrifugal force and dynamic load transfer under high-speed emergency lane change conditions is suppressed by a hierarchical control mechanism. The joint simulation results from TruckSim and Simulink indicate that, under the double lane change scenario with 88 km/h, the lateral force balance strategy reduces the rollover angles of the tractor and trailer by 85.5% and 86.9%, respectively, and the center of gravity lateral offset is improved by 77.5% and 92.3%; under the double lane change scenario with 80 km/h, compared with the active steering strategy of the trailer, the lateral load transfer rate fluctuation is reduced to the percentile level, and the rollover angles decrease by 62.9% and 65.3%.
Zhang, Qiyuan, Zhang, Lei, Liao, Shengkun, Sun, Jinxu, He, Jing
Vibration Dynamics of a Half-Car Model Considering Tire–Road Separation02-19-04-00212/9/2026
The vibrating half-car model is used to represent the dynamic behavior of a truck’s dependent suspension system, capturing four degrees of freedom. This research investigates time and frequency responses of vibration behavior of half-car model with possible tire–road separation. This investigation is significant because all previously reported analyses based on the tire-road attachment were incorrect, particularly regarding the tire-road separation phenomenon. The differential equations are extended to enhance the accuracy of the model, incorporating tire–road separation conditions for both wheels. A numerical approach is applied to simulate the vertical and roll dynamics of the system under the separation assumption. The simulation results are validated through experiments conducted using ADAMS View software. Integrating the tire–road separation into the model results in dynamic responses that closely reflect real-world behavior. These findings provide valuable guidance for designing more effective suspension systems and for developing control strategies aimed at reducing rollover risk and enhancing lateral stability.
Nguyen, Quy Dang, Jazar, Reza
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