Browse Topic: Rear-end crashes

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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
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
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.
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
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
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
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
Real-Time Lane Change Risk Estimation Using Extended Lane Change Risk Index (ELCRI) and Fault Tree Analysis2026-26-00401/16/2026
Accidents during lane changes are increasingly becoming a problem due to various human based and environment-based factors. Reckless driving, fatigue, bad weather are just some of these factors. This research introduces an innovative algorithm for estimating crash risk during lane changes, including the Extended Lane Change Risk Index (ELCRI). Unlike existing studies and algorithms that mainly address rear-end collisions, this algorithm incorporates exposure time risk and anticipated crash severity risk using fault tree analysis (FTA). The risks are merged to find the ELCRI and used in real time applications for lane change assist to predict if lane change is safe or not. The algorithm defines zones of interest within the current and target lanes, monitored by sensors attached to the vehicle. These sensors dynamically detect relevant objects based on their trajectories, continuously and dynamically calculating the ELCRI to assess collision risk during lane changes. Additionally, adherence to R79 regulations and usage of safety distances enhance the algorithms handling uncertainties in the system and environment. Additionally, separate thresholds for ELCRI in each zone allow modular lane change assessments. The inclusion of the above additions to the algorithm serves as an extension to already existing similar risk index concepts, therefore the term “Extended” LCRI has been used. The algorithm has been tested in simulated scenarios and compared with real-world data to evaluate its strengths and limitations. While very high relative velocities between the object and self-vehicle can affect ELCRI accuracy, the algorithm has proven effective in improving lane change safety under typical traffic conditions.
Dharmadhikari, Mithil, S, Mrudula, Nair, Nikhil, Malagi, Gangadhar, Paun, Cristin, Brown, Lowell, Korsness, Thomas
Conceptual Crash Analysis in Automotive Applications with Reduced Computational Effort2026-26-04511/16/2026
In the realm of automotive safety engineering, the demand for efficient and accurate crash simulations is ever-increasing. As finite element (FE) modeling of components becomes increasingly detailed and the availability of advanced material models improves, crash simulations for full vehicles can become time-consuming. Evaluating the crash performance of any vehicle subsystem requires structural simulations at different levels. While the design and configuration phase deals with a local simulation in representative load cases, full vehicle simulations are required later for a final digital proof of achieved requirements and development targets. This paper introduces a novel methodology for replacing full vehicle crash simulations, as required for a local view on the structural load path development, through segment-models. By adapting segment-model simulations, a significant reduction in computational time and resource usage is achieved, thereby optimizing CPU cluster performance and minimizing the effort invested in time and model handling. A closer look at these kinds of representative models can even consider a higher resolution in local regions, necessary to capture the structural behavior through a crash load case much more accurately. The proposed method has been successfully implemented across various scenarios, including full-frontal crash load cases with 100 percent overlap, 40 percent overlap, small overlap crash load cases, side impact, rear impact, underbody impact, and low-speed impact scenarios. The results from these segment-model simulations exhibit strong correlation with full vehicle simulations, ensuring reliability and validity of the presented work. This approach not only enhances simulation efficiency and cluster utilization cost but also offers a scalable solution for future automotive crash evaluation and optimization. The findings underscore the potential for widespread application of segment-models or cut models in the industry as important surrogate models, paving the way for more sustainable and cost-effective crash simulation practices.
Moncayo, David, Malipatil, Anand, Prasad, Rakesh, Kunnath, Allwin
Influence of Impact Configuration on Rear Compartment Intrusion and Structural Countermeasures2026-26-04621/16/2026
The impact configuration has a strong influence on the rear seat survival space intrusion pattern during severe rear-impact collisions. The relative contributions of rear seat pan forward intrusion versus rear seatback intrusion vary depending on the nature of the crash. In underride impacts, the rear wheels are pushed forward into the occupant survival space from below, causing the rear seat-pan to move forward and upward relative to the vehicle interior. Conversely, override impacts tend to produce direct seatback intrusion into the rear compartment. This study used a validated computer model from the NHTSA website to simulate various types of rear compartment intrusions under different impact configurations. The analysis also assessed structural countermeasures designed to minimize occupant survival space intrusion. The results demonstrate that underride impacts primarily drive the forward motion of the rear wheels into the structure, establishing load paths that lead to structural failures and forward propulsion of the seat pan, in contrast to the seatback-dominant intrusion observed in override impacts. Furthermore, the study shows that structural reinforcements located above, and below the beltline are effective in mitigating survival space intrusion across different rear-impact scenarios.
Thorbole, Chandrashekhar, Vhanaje, Manoj G, Eknath Chopade, Santosh
Rear-Facing Infant Seat Structural Integrity and Crashworthiness under Front Seatback Loading in Rear-Impact Collisions2026-26-05541/16/2026
Rear-facing infant seats that are positioned behind front outboard vehicle seats are at risk of being compromised by the rearward yielding of occupied front seat seatbacks during rear-impact collisions. This movement can cause the plastic shell of the infant seat to collapse and deform, increasing the risk of head injuries to the infant. Current designs of rear-facing infant seats typically do not consider the loading effects from the front seatback during rear-impact situations, which results in weak and collapsible shell structures. Moreover, regulatory compliance tests, such as FMVSS 213, do not include assessments of rear-facing infant seats under realistic rear-impact conditions. as the bench used for the regulatory test lacks realistic vehicle interior components. This study emphasizes the need for revised testing methodologies that employ sled tests with realistic seatback intrusion conditions to facilitate the development of improved infant seat designs. Research shows that rear-facing infant seats designed for real-world loading conditions can improve safety and injury outcomes for infants in severe rear-impact collisions in the presence of front-occupied seats.
Thorbole, Chandrashekhar
An Innovative Collision Sensing Architecture for Robust Functionality of Safety Restraint Systems in Different Challenging Real World Accident Scenarios2026-26-00171/16/2026
In emerging markets, especially in India and other similar countries, the growing traffic density on the roads leads to different types of accidents, including frontal head-on collisions, rear-end collisions, side-impact collisions, collisions with fixed objects such as electric poles, trees, road guard rails, road dividers, and accidents involving pedestrians, cyclists, and two-wheelers. These accidents could be due to over speeding, distracted driving, violation of traffic rules, and inadequate road infrastructure etc. Providing the necessary safety restraint systems (Airbags and Seat belts) in vehicles and ensuring their robust functionality in different real-world accident scenarios will be challenging for vehicle manufacturers. It is high time to redefine the traditional collision-sensing architecture strategies with a logical approach based on a thorough study of available accident data statistics, types of objects, and scenarios leading to severe accidents. Among these, rear-end collisions (such as car-to-truck under-ride), side collisions, and head-on collision accident cases are increasing day by day. Ineffective sensing of collision signals and inadequate functionality of the safety restraint system can lead to severe injuries or fatalities. It is imperative to improvise the collision sensing system architecture and place the crash sensors inventively at optimal locations in the vehicle with an innovative approach for the early detection of collision signals and for the robust functionality of the safety restraint systems to mitigate occupant injuries and reduce fatalities to the maximum extent. This technical paper describes the thought process and methodology used to improve collision sensing techniques for the robust functionality of safety restraint systems in rear-end collisions (mainly car-to-truck underride), side impact collisions, head-on collisions, and undercarriage/underbody scraping scenarios (especially for EV battery packs). This innovative collision-sensing architecture system can be introduced in vehicles to cater to the needs of robust functionality of safety restraint systems (Airbags and Seat belts) in different real-world accident scenarios to protect vehicle users with improvisation in the existing situations while ensuring fuel cut-off in the case of ICE and high-voltage cut-off in the case of EV vehicles.
KOVALAM, SUNIL KUMAR
Single Radar: A Robust and Cost-Effective Solution for ADAS and Parking Functionality2026-26-00491/16/2026
With rapid advancements in Autonomous Driving (AD) & Advanced Driver Assistance Systems (ADAS), numerous sensors are integrated in vehicles to achieve higher and reliable level of autonomy. Due to the growing number of sensors and its fusion creates complex architecture which causes challenges in calibration, cost, and system reliability. Considering the need for further ADAS advancements and addressing the challenges, this paper evaluates a novel solution called One Radar - a single radar system with a wide field of view enabled by advanced antenna design. Placing the single radar at the rear of the vehicle eliminates the need for corner radars and ultrasonic sensors used for parking assistance. With rigorous real-world testing in different urban and low-speed scenarios, the single radar solution showed comparable accuracy in object detection with warning and parking assistance to the conventional combination of corner radars and ultrasonic sensors. The simple single sensor-based architecture not only reduces signal processing complexity and development time but also minimizes interference risks that comes with multiple sensor setup. This innovation results in a significant reduction in the Bill of Materials (BOM) for manufacturers by up to 40% for rear/side sensing modules, lowering production costs and enabling more affordable ADAS-equipped vehicles for end customers. Additionally, the simplified design enhances scalability for mass market adoption. The research paper talks about the single radar performance in various use cases to validate the features such as Rear parking alert system (RPAS), Door open warning (DOW), Blind spot detection (BSD), Lane change warning (LCW) and Rear collision warning (RCW) functionalities, highlighting its versatility as a standalone sensor module for future autonomous systems.
Anandan, Ram, Sharma, Akash
Enhancing Energy Absorption in Rear Impact Events through Rail Extension Design and Material Variations2025-36-009612/18/2025
Safety improvements in vehicle crashworthiness remain a primary concern for automotive manufacturers due to the increasing complexity of traffic and the rising number of vehicles on roads globally. Enhancing structural integrity and energy absorption capabilities during collisions is paramount for passenger protection. In this context, longitudinal rails play a critical role in vehicle crashworthiness, particularly in mitigating the effects of rear collisions. This study evaluates the structural performance of a rear longitudinal rail extender, characterized by a U-shaped, asymmetric cross-section, subjected to rear-impact scenarios. Seventy-two finite-element models were systematically developed from a baseline configuration, exploring variations in material yield conditions, sheet thickness, and targeted geometric modifications, including deformation initiators at three distinct positions or maintaining the original geometry. Each model was simulated according to ECE R32 regulation standards, ensuring validity and compliance with relevant safety criteria. Specific energy absorption (SEA), load uniformity, and structural acceleration were used as key measures of crashworthiness. Simulation outcomes indicated that reductions in thickness significantly increased SEA due to enhanced deformability. Thinner configurations demonstrated greater energy absorption and improved load uniformity, whereas thicker components increased structural rigidity, resulting in decreased energy absorption and higher accelerations transmitted to the vehicle’s B-pillar. Material properties had moderate influence, with higher-strength materials elevating accelerations. Geometric modifications, particularly deformation initiators at specific positions, substantially improved SEA, achieving enhancements up to 42% compared to baseline. These findings highlight the potential of strategic adjustments in geometry, material selection, and thickness to significantly enhance vehicle crashworthiness and occupant safety.
Souza Coelho Freitas, Victor de, Pereira, Romulo Franco, Souza, Daniel Souto de
Prediction of Automotive Seat Response Based on IPSO-BP Neural Network2025-99-012411/11/2025
To enhance the predictive accuracy between seat structural parameters and crash performance, a hybrid model was constructed by coupling an Improved Particle Swarm Optimization (IPSO) algorithm with a Back Propagation Neural Network (BPNN). First, a finite element model for front and rear impact of automotive seats was established based on experimental data, and the model’s accuracy was verified. Subsequently, simulations were conducted, and the results were analyzed. The Energy Absorption Mass Ratio method was used to screen the design variables, ultimately selecting 10 thickness variables and 9 material variables as design variables. Latin Hypercube Sampling was employed to divide the dataset into a testing set and a training set. Then, the Particle Swarm Optimization (PSO) was enhanced with Levy flights and a local mutation strategy, utilizing the IPSO algorithm to optimize the initial weights and thresholds of the BPNN, resulting in the establishment of the IPSO-BPNN predictive model. The results indicate that the proposed IPSO-BPNN shows significant advantages in predicting the output of automotive seats.
Qiu, Yufei, Long, Jiangqi
Balancing Safety, Stability, and Comfort in Semi-Truck Platooning: A Study on Safe and Optimal Headways under Real-World Traffic Conditions2025-99-001710/17/2025
On highways, platoons of semi-trucks are a common phenomenon. By maintaining a small headway, these platoons can effectively reduce air resistance, thereby improving fuel efficiency and reducing carbon emissions. However, this driving mode is also accompanied by many safety and operational risks, such as increased risk of rear-end collisions, reduced driving comfort, and susceptibility to interference from other vehicles outside the platoon. Therefore, behavioral analysis and evaluation of semi-truck platoons naturally formed in real traffic environments are of great significance for improving their driving safety, comfort and stability. This study focuses on the headway characteristics of semi-truck platoons, analyzes their headway distribution, headway gap and braking response behavior, and then proposes a safe headway threshold for emergency braking to effectively reduce the probability of rear-end collisions. In addition, the study also defines an optimal headway range to reduce the possibility of external vehicle insertion, thereby improving the overall stability and driving experience of the platoon. Based on this, this paper constructs a semi-truck platoon model with safety as the core, and verifies it with actual traffic data, revealing the behavioral characteristics of naturally formed semi-truck platoons in terms of safety headways, optimal headways, and platoon distributions. The research results not only provide theoretical support for improving the safety and stable operation of naturally formed truck platoons, but also provide technical reference for the deployment and operation of future connected and automated truck (CAT) platoons in real road environments, helping the freight industry to develop in a more efficient and sustainable direction.
Hu, Xiaoqiang, Cao, Qiang
Pulse and Polynomial Functions to Predict Vehicle Acceleration Using Event Data Recorder Delta-V in Frontal and Rear-End Collisions2025-01-50466/27/2025
The lack of recorded acceleration and limited Delta-V (ΔV) resolution in many vehicle event data recorders necessitates the development of a method to predict continuous vehicle acceleration based on ΔV responses. This study developed a method of obtaining continuous acceleration by regressing pulse functions (triangular, half-sine, haversine) and polynomial functions (orders 3–6) to a ΔV curve and deriving the corresponding acceleration–time curve. The effectiveness of this method was demonstrated using real-world ΔV response data from front and rear-end collisions. Comparisons were performed between peak and average acceleration values from each front and rear-end crash pulse. Results indicated that a triangular pulse function predicted similar peak acceleration values to the vehicle’s actual acceleration in frontal and rear-end impacts. Average acceleration in frontal impacts was best predicted utilizing a fifth-order polynomial, while a sixth-order polynomial demonstrated the best predictive ability for rear-end impacts. Obtaining equations for vehicle ΔV and acceleration is crucial in assessing impact severity due to the vehicle’s dynamic response.
Westrom, Clyde, Adanty, Kevin, Shimada, Sean D.
Head Accelerations and Concussion Risks in Low-to-Moderate–Speed Rear-End Collisions2025-01-50416/10/2025
Recent studies have investigated head injury metrics, including mild traumatic brain injury (mTBI), or concussion risks, in low- to moderate-speed rear-end collisions, with linear and angular head accelerations contributing to the risk of developing a concussion. The present study analyzes head acceleration values in rear-end collisions at an impact severity of 5–30 km/h delta-V. Biomechanical data was obtained from HIII 50th percentile male anthropomorphic test devices (ATDs) seated in the target subject vehicles and utilizing safety restraints and head rests. Concussion risks were calculated from resultant linear and angular head accelerations recorded in the ATDs, and a linear regression model was used to determine what, if any, relationship existed between these head injury metrics and impact severity. The results indicate that there is a significant and positive relationship between head acceleration metrics and impact severity, particularly in the sagittal plane, with F-values < 0.05. Additionally, there is a positive relationship between concussion risks and impact severity, but results also determine that the concussion risks are less than 0.1% and indistinguishable from 0 at this range of impact severity. An outlier test that included head impact with a rear-seated passenger ATD yielded a less than 2% risk of sustaining a concussion. It is expected that the results of this study will aid in accident reconstruction and biomechanical analysis for restrained occupants involved in low- to moderate-speed rear-end collisions.
Garcia, Beatriz, Emanet, Hatice Seyda, Hoffman, Austin
Occupant Restraint and Equipment Mounting Integrity - Rear Impact Ambulance Patient CompartmentJ3044_202505 (Current)5/20/2025
This SAE Recommended Practice describes the test procedures for conducting rear impact occupant restraint and equipment mounting integrity tests for ambulance patient compartment applications. Its purpose is to describe crash pulse characteristics and establish recommended test procedures that will standardize restraint system and equipment mount testing for ambulances. Descriptions of the test set-up, test instrumentation, photographic/video coverage, and the test fixtures are included.
Truck Crashworthiness Committee
Development of a Generic Nearside Impact Test Fixture for Evaluating In-Vehicle Crashworthiness of Wheelchairs2025-22-00025/13/2025
Current voluntary standards for wheelchair crashworthiness only test under frontal and rear impact conditions. To help provide an equitable level of safety for occupants seated in wheelchairs under side impact, we developed a sled test procedure simulating nearside impact loading using a fixed staggered loading wall. Publicly available side impact crash data from vehicles that could be modified for wheelchair use were analyzed to specify a relevant crash pulse. Finite element modeling was used to approximate the side impact loading of a wheelchair during an FMVSS No. 214 due to vehicle intrusion. Validation sled tests were conducted using commercial manual and power wheelchairs and a surrogate wheelchair base fixture. Test procedures include methods to position the wheelchair to provide consistent loading for wheelchairs of different dimensions. The fixture and procedures can be used to evaluate the integrity of wheelchairs under side impact loading conditions.
Boyle, Kyle, Hu, Jingwen, Manary, Miriam, Orton, Nichole R., Klinich, Kathleen D.
Overview of Seat Design Changes and Performance2025-01-87294/1/2025
The National Highway Traffic Safety Administration (NHTSA) published an Advance Notice of Proposed Rulemaking (ANPRM) to update the Federal Motor Vehicle Safety Standard (FMVSS) 207. Part of the ANPRM is to assess the merit of conducting quasi static body block seat pull tests and conducting FMVSS 301 rear crash tests at 80 km/h or higher with a 95th percentile ATD lap-shoulder belted in the front seats and limiting seatback deflection to 15 to 25 degrees. Prior to updating regulations, it is important to understand the seating design history and implications. This study was conducted to provide a historical background on seat design and performance using literature and test data. One objective was to first define the terminology used to describe occupant kinematics in rear crashes. Secondly, seat design evolution is then discussed. Third, test methods and test results were summarized, and fourth, the field performance are synopsized and discussed with respect to 2nd row occupant protection. Seat design evolution: Seat designs have continuously evolved for the last 70 years, including changes in seat structure and seat/head restraint geometry. Over the past decades, seatbacks have become taller and include open perimeter frames and dual recliners. Head restraints have become larger and/or more forward. Seat properties have also changed over time, resulting in better performance. These changes resulted in an increase in strength. The changes in design and properties allow the occupant to pocket while offering load-limiting and controlled head and neck support. Test method summary: Various methods are used to evaluate seat performance, including quasi-static pull tests and dynamic sled tests. Pull tests include applying a rearward load at the upper cross member of the seatback frame, which does not account for the interaction between the occupant and the seat. Other test methods include using a body block as suggested in the ANPRM. Many tests have been conducted with the body block representative of the upper torso geometry and center of gravity (cg) of a 50th percentile occupant. The data show a continuous increase in rearward loading strength, averaging 1,232 Nm (10,902 in-lbs) in seats with model year (MY) 1989 and older and 3,244 Nm (28,716 in-lbs) in MY 2010+, decreasing dynamic seatback rotation. FRED (Ford Rear-Impact Energy Device) is another type of device used in pull testing. FRED provides a more biofidelic test for occupant loading and interaction with the seat; the load location coincides with the cg of a 50th percentile occupant. However, there is less FRED data available for historical comparisons. Sled tests are conducted at low-to-moderate speeds and at high-speed. For example, low-to-moderate speed sled tests are conducted at 16 km/h as part of the Insurance Institute Highway Safety (IIHS) head restraint evaluation program, terminated in 2022, and at 17.3 km/h as part of FMVSS 202a. Testing and field performance: The result of this study suggests that the newer seat designs are performing well. Modern seats (2010+ MY) exceed the FMVSS 207 static strength requirement by a factor greater than 8 on average. Dynamic sled tests, conducted with the BioRID and with the 50th Hybrid III, show good performance. The occupant biomechanical responses obtained from 40 km/h rear sled tests remain well below injury thresholds. There was a decrease in neck extension. Chest g’s 3ms however remined similar irrespective of MY group; it averaged 14.6 ± 4.6g with 1990-1999 MY- and 15.7 ± 2.4g in 2010+ MY seats. In either the earlier or more recent MY vehicles, these peak chest accelerations occurred prior to maximum seatback deflection. Conclusion: These results of this study provide background for consideration of future test requirements. Overall, conducting dynamic sled tests with a FMVSS 301R impact energy and 50th percentile male ATD may be valuable. However, selecting a maximum dynamic deflection limit would require additional work, as it may affect seat yielding performance. Yielding is beneficial for overall crash safety, particularly for older and/or more vulnerable occupants. Protecting rear seat occupants from front seat interaction may be the reasoning behind limiting the seatback deflection. Care must be taken in understanding the cause of injury risk to rear occupants when considering design changes that may influence the risk to front seat occupants, especially since the front seats are occupied at a higher rate than rear seats. For example, the literature review indicates that factors outside of front seat design such as intrusion were a significant factor on second-row occupant injury outcomes. The size of the BioRID and 50th Hybrid III used in sled testing is representative of an average driver involved in tow-away crashes. Conducting tests with 95th percentile ATD may thus bias the data and could have unintended consequences for smaller or vulnerable occupants.
Parenteau, Chantal, Burnett, Roger, Davidson, Russell
The Influence of out-of-Position Displacement during Emergency Braking on Occupant Whiplash Injury in Subsequent Rear-End Collisions2025-01-87204/1/2025
In the pre-crash emergency braking scenario, the occupant inside the vehicle will move forward due to inertia, deviating from the standard upright seating position for which conventional restraint systems are designed. Previous studies have mainly focused on the influence of out-of-position (OOP) displacement on occupant injuries in frontal collisions, and provided solutions such as active pretensioning seatbelts (APS). But little attention has been paid to the influence of OOP on whiplash injury during a subsequent rear-end collision. To investigate the forward OOP impact on whiplash injuries and the effectiveness of APS in this accident scenario, a vehicle interior model with an active human body model (AHBM) was setup in the MADYMO simulation platform. Different braking strengths (0.8g and 1.1g), APS triggering times (from 0.2s before to 0.2s after the braking initiation) and pretensioning forces (from 100N to 600N) were input to the simulation matrix. The occupant’s forward OOP displacement prior to the rear-end collision and the corresponding whiplash injury metrics including neck shear force, tension force, and neck injury criteria (NIC) in the subsequent moderate rear-end collision were recorded. The simulation results indicated that: (1) The occupant’s whiplash injury metrics were positively linearly correlated with the pre-crash forward OOP displacement. (2) The APS could not fully eliminate the forward displacement brought by neck flexion, causing whiplash injury metrics to exceed the capping limits (upper bounds) defined in current vehicle safety assessment protocols like Euro-NCAP.
Fei, Jing, Qiu, Hang, Wang, Peifeng, Liu, Yu, Cheng, James Chih, Zhou, Qing, Tan, Puyuan
A Chronology of Research and Events to-Date Significant to Occupant Protection in Rear-End Automobile Impacts2025-01-87254/1/2025
Theory and principles of occupant protection for automobiles in rear-end collisions have experienced significant evolution over the decades. Performance of the seatback, specifically the stiffness of the structure, during such a collision has been a subject of particular interest and debate among design engineers, accident reconstruction experts, critics, etc. The majority of current seat designs rely on plastic deformation of the seatback structure to protect the occupant from the dynamics of the crash. In attempt to highlight and provide background information for understanding this subject, this work highlights significant events, research, and publications over the past five decades to illustrate how this subject, automobile design, government regulation and public opinion has evolved. It is observed that technology and design for improving rear-impact protection has received less attention than collisions of other principal directions of force. The different types of Anthropometric Test Devices (ATDs) used in research are quantified. Lessons may be learned by design engineers to ensure seatback safety moves forward with progress to improve future generations of automobile seats. It is also observed that the quantity of published works could be influenced by historical events as well as certain research topics trending in the automotive industry.
Warner, Wyatt
The Biomechanical Effects of Neck and Back Cushion / Pillow / Support Devices in Low-Speed Rear Impacts2025-01-87284/1/2025
There are numerous commercially available neck and back support/cushion/pillow devices which are commonly attached to seats by vehicle owners. To our knowledge, there has been no published research on the biomechanical effects of these devices in low-speed rear impacts. To address this, a series of 54 simulated low-speed rear impact tests were conducted using a validated remote-controlled crash sled system. All tests utilized an instrumented BioRID II rear impact anthropomorphic test device (ATD) restrained using a 3-point seatbelt system in a 2018 Toyota Camry LE driver’s seat. Two delta-V ranges were used: a lower range from 7.2 to 8.0 kph (4.5 to 5.0 mph) and a higher range from 10.5 to 11.3 kph (6.5 to 7.0 mph). Six neck only devices, one combination neck and back device, and three back only devices were assessed. Two tests per delta-V range for each device and each device adjustment position were conducted and compared against five reference tests without any devices at each delta-V range. Statistical analyses and comparison of the biomechanical responses between each neck only and back only devices and the reference tests at each delta-V range were conducted. Additionally, Nkm, LNL, WIC, and NIC were calculated for each test. While not all devices and/or delta-V ranges showed consistent effects, the results indicated trends for certain peak biomechanical measures. Specifically, these support devices demonstrated a tendency to increase the tension forces in the upper neck, lower neck, and lumbar spine. Additionally, the back support devices tended to increase the head-to-head restraint contact forces as well as upper neck flexion (positive) moments. This study presents a parametric investigation into the biomechanical effects of various neck and back support/cushion/pillow devices during lower-speed rear impact exposures. The focus is on assessing changes in biomechanical measures associated with the use of these devices, and the injury criteria calculated should only be compared with the reference tests.
Phan, Andrew, Gross, Jamie, Umale, Sagar, Crowley, Shannon, Glasser, Gabriel, Furbish, Christopher
Development and Validation of a Rear Head Surround Foam Performance Specification for Stock Car Racing2025-01-83534/1/2025
Over the last two decades many improvements have been made in stock car racing driver safety. One of these is the head surround, which is rigidly secured to and an integral part of the NASCAR (National Association for Stock Car Auto Racing, LLC) seating environment and serves as an effective restraint for head protection during lateral and rear impacts. However, previous head impact material specifications were optimized for moderate to severe impacts and did not address low severity impacts that occur frequently during typical driving, such as race restart vehicle nose-to-tail contact. This study focused on developing a test methodology for comprehensive evaluation of rear head surround materials for low, moderate and severe impacts. Specifically, this study aimed to formulate a specification that maintains previous material performance during high speed impacts, while decreasing head accelerations at low speed impacts. Quasi-static and dynamic drop tower testing of sample materials were used to analyze the energy absorption capabilities of various materials. Finite element material models were developed to assess the effects of foam thickness on head kinematics. Anthropomorphic test device (ATD) empirical sled testing was used to analyze material responses in the full NASCAR seating environment. In drop tower testing, the new materials achieved nearly a 33% reduction in peak acceleration for 2.2 m/s (5 mph) impacts compared to the baseline materials while maintaining original peak acceleration and rebound velocity performance at 5.8 m/s (13 mph). Empirical sled testing confirmed equal performance to the baseline materials at high velocity, as well as a 5 to 15 G decrease in peak resultant head acceleration at low speed depending on comparison samples. Study findings resulted in updates to the NASCAR rulebook including increasing the minimum thickness of the original rear head surround foam material and the use of the newly specified alternate foam materials in the field. The alternate foams drop test requirements include 24 total drop tests on 12 test samples per material evaluation, at two speeds (2.2 and 5.8 m/s) and two temperatures (21° and 50° C). The repeated impacts are conducted at the same test speed, for each temperature, on the same sample. Material performance evaluations include peak acceleration, maximum rebound velocity, and flame retardancy.
Gray, Alexandra N., Harper, Matthew G., Mukherjee, Sayak, Patalak, John P., Gaewsky, James
Do Aftermarket and Original Equipment Forward Collision Warning Systems Respond the Same to Vehicles and Pedestrians?2025-01-86774/1/2025
About 32% of registered vehicles in the U.S are equipped with automatic emergency braking or forward collision warning (FCW) systems [1]. Retrofitting vehicles with aftermarket devices can accelerate the adoption of FCW, but it is unclear if aftermarket systems perform similarly to original equipment manufacturer (OEM) systems. The performance of four low-cost, user-installable aftermarket windshield-mounted FCW systems was evaluated in various Insurance Institute for Highway Safety (IIHS) rear-end and pedestrian crash avoidance tests and compared with previously tested OEM systems. The presence and timing of FCWs were measured when vehicles approached a stationary passenger car at 20, 40, 50, 60, and 70 km/h, motorcycle and dry van trailer at 50, 60, and 70 km/h, adult pedestrian at 40 and 60 km/h, and child pedestrian crossing the road at 20 and 40 km/h. Equivalence testing was used to determine if FCW performance was similar for aftermarket and OEM systems. OEM systems provided a warning in 95% of trials, while aftermarket systems warned in 67%. Performance was similar with the passenger car, but aftermarket systems warned in significantly fewer trials with the motorcycle, dry van trailer, and child pedestrian. On average, OEM systems warned 1.1 to 2.5 seconds before impact with different targets, while the aftermarket systems warned 0.3 to 3.5 seconds before impact. The findings indicate that existing aftermarket FCW systems can address the most common rear-end crash type involving other passenger cars but not rear-end crashes involving motorcycles or heavy trucks or crashes with pedestrians, all of which are more likely to be fatal. By expanding existing testing programs to aftermarket devices, regulatory agencies and consumer information organizations can inform consumers about the technologies, accelerate adoption, and encourage aftermarket device manufacturers to improve the performance of their systems so that the devices can provide the safety benefits observed with OEM systems.
Kidd, David, Floyd, Philip, Aylor, David
Aggregation of Cervical Loads in Rear Impact Crash Tests and Comparison to Activities of Daily Living2025-01-87084/1/2025
Peak upper and lower neck load data from rear impact crash testing were reviewed, aggregated, and analyzed from over 1,800 tests of existing peer-reviewed literature and research as well as available testing conducted by the Insurance Institute for Highway Safety (IIHS) and the National Highway Traffic Safety Administration (NHTSA). Both human volunteers and anthropomorphic test devices (ATDs) were subjects of the reviewed studies and testing. Peak upper and lower neck axial forces (compression and tension), sagittal shear forces, and sagittal moments (flexion and extension) from available crash testing were reported and analyzed as functions of measured change in velocity (delta-V) ranging from approximately 3 to 60 km/h (1.9 to 37 mph). This load data was then further analyzed for possible trends amongst various testing conditions, such as seat type, ATD used, and subject seating position within the vehicle chassis and seat to develop a simple linear model. The linear regressions developed from rear impact crash testing suggest that a relationship does exist between peak cervical spine loading and delta-V. For the upper neck, peak tension and compression showed the highest correlations with respect to delta-V, seen in their calculated R2 values of 0.37 and 0.29, respectively. For the lower neck, peak tension and extension moments showed the highest correlations with respect to delta-V (R2 of 0.48 and 0.45, respectively) while peak compression had the lowest correlation (R2 = 0.08). The same cervical spine loads were also aggregated from studies that measured loading in various activities of daily living (ADLs), such as everyday tasks and activities typically undergone by amusement park patrons and athletes. The analyzed ADLs produced cervical spine loading that was generally greater than or comparable to the aggregated data from crash testing and sled tests that underwent delta-Vs of less than approximately 24 km/h (15 mph), except for peak tensile forces. The data suggests that participants of related everyday activities may undergo peak cervical spine loading similar to what is experienced by normally seated occupants in lower-speed (delta-V less than 24 km/h (15 mph)) rear impact motor vehicle collisions.
Kazmierczak, Alex, Umale, Sagar, Visalli, Alyssa, Webb, Ella, Kashdan, Aryeh, Randles, Bryan, Welcher, Judson
A Study on Affections of Active Neck Muscle Force on Neck Injury Responses in Frontal Impact with Automatic Emergency Braking Conditions2025-01-87424/1/2025
Neck injury is one of the most common injuries in traffic accidents, and its severity is closely related to the posture of the occupant at the time of impact. In the current era of smart vehicle, the triggered AEB and the occupant's active muscle force will cause the head and neck to be out of position which has significant affections on the occurrence and severity of neck injury responses. Therefore, it is very important to study the influences of active muscle force on neck injury responses in in frontal impact with Automatic Emergency Braking conditions. Based on the geometric characteristics of human neck muscles in the Zygote Body database, the reasonable neck muscle physical parameters were obtained firstly. Then a neck finite element model (FEM) with active muscles was developed and verified its biofidelity under various impact conditions, such as frontal, side and rear-end impacts. Finally, using the neck FEM with or without active muscle force, a comparative study was conducted on the kinematics and injury responses of the neck in the frontal impact with AEB condition. The research findings indicate that the activation of cervical active muscle forces effectively reduces the displacement of the head's center of gravity prior to the collision and significantly decreases the relative angular displacements between cervical vertebrae during the collision. These dynamic response changes mitigate the injury severity of cervical vertebrae, ligaments, and intervertebral discs, thereby enhancing the biomechanical tolerance of the cervical structure to mechanical loads.
Junpeng, Xu, Gan, Qiuyu, Jiang, Binhui, Zhu, Feng
Lightweight Optimization of an Electric Bus Body Frame Based on the C 2 oDE Algorithm2025-01-86544/1/2025
In this work, design optimization for the lightweight of the body frame of a commercial electric bus with the requirements of stiffness, strength and crashworthiness is presented. The technique for order preference by similarity to ideal solution (TOPSIS) is applied to calculate the components that have a great impact on the output response of the static modal model and the rear-end collision model. The thickness of the five components with the highest contribution in the two models is determined as the final design variable. Design of experiment (DOE) is carried out based on the Latin Hypercube sampling method, and then the surrogate models are fitted by the least squares regression (LSR) method based on the DOE sampling data. The error analysis of the surrogate model is carried out to determine whether it can replace the finite element (FE) model for optimization, then the optimization scheme for lightweight optimization of electric bus frame is implemented based on the algorithm of composite differential evolution for constrained evolutionary optimization (C2oDE). Comparing the optimization results with the initial values, it can be found that the mass of the electric bus body frame is reduced by 51.59kg with a reduction rate of 4.99%. Meanwhile, the energy absorption of the rear wall increases by 2.79%, the maximum intrusion is reduced by 0.36%, the intrusion velocity at the center of the rear wall of the electric bus body frame is reduced by 0.46%, the acceleration at the cabin center is reduced by 3.29%, and the crashworthiness performance of the electric bus body frame is also improved.
Yang, Xiujian, Tian, Dekuan, Liu, Jiaqi, Cui, Yan, Lin, Qiang
Assessment of Injuries in Rear Impacts2025-01-87274/1/2025
Rear impacts make up a significant portion of crashes in the United States. To date, regulations on rear impacts have focused on fuel system integrity and seat performance, while most research has focused on seat performance in relation to occupants’ injuries, with some analyses of crash severity and seat belt effects. The performance of seats and seat belts may vary depending on the size of the occupant. Understanding how occupant characteristics, as well as crash scenarios, affect injury outcomes can show opportunities for further enhancements in rear impact occupant protection. This paper presents analyses using survey weighted logistic regression models to understand the factors affecting serious injury outcomes (i.e., MAIS 3+) in rear impacts, exploring the potential for improving occupant outcomes. Three separate models are evaluated, focusing on 1) overall injury level, 2) head, neck, and cervical-spine injuries, and 3) thorax, abdomen, thoracic- and lumbar-spine injuries for drivers in rear impacted passenger vehicles. Results show that significant factors vary by injured body region and highlight potential opportunities for enhancing occupant protection.
Greib, Joshua, Jurkiw, Renee, Kryzaniwskyj, Tanja, Owen, Susan, Van Rooyen, Paul, Whelan, Stacey, Williamson, John
Design of an Integrated Crash Safety Test Scenario: Rear-End Collision in SUBSEQUENCE of Emergency Braking2025-01-87474/1/2025
The integrated vehicle crash safety design provides longer pre-crash preparation time and design space for the in-crash occupant protection. However, the occupant’s out-of-position displacement caused by vehicle’s pre-crash emergency braking also poses challenges to the conventional restraint system. Despite the long-term promotion of integrated restraint patterns by the vehicle manufacturers, safety regulations and assessment protocols still basically focus on traditional standard crash scenarios. More integrated crash safety test scenarios and testing methods need to be developed. In this study, a sled test scenario representing a moderate rear-end collision in subsequence of emergency braking was designed and conducted. The bio-fidelity of the BioRID II ATD during the emergency braking phase is preliminarily discussed and validated through comparison with a volunteer test. The final forward out-of-position displacement of the BioRID II ATD falls within the range of volunteer displacements. The test results indicate that conducting this integrated rear-end collision scenario via sled test is feasible, and integrated restraint patterns, such as active pretensioning seatbelts, effectively reduces whiplash injury parameters, demonstrating the potential significance of carrying out this assessment scenario.
Fei, Jing, Wang, Peifeng, Qiu, Hang, Liu, Yu, Shen, Jiajie, Cheng, James Chih, Zhou, Qing, Tan, Puyuan
Feasibility of Road Longitudinal Profiles for Automated Vehicles Based on Vehicle Dynamics2025-01-71503/19/2025
With the development and maturity of new generation digital technologies such as artificial intelligence, Internet of Things, and 5G mobile communication, their integration with physical products is becoming increasingly seamless. Automobiles serve as a prime example in this regard. In recent years, automated vehicle (AV) technologies have emerged as a prominent focal point, witnessing an escalating acceptance in the market and a growing number of self-driving vehicles on the roads, existing roads are primarily designed for traditional human-driven vehicles (HVs). Due to the differences in perception between automated systems and human drivers, it is essential to assess AVs' feasibility to current road infrastructure. This paper analyzes the safety and comfort of automated vehicles equipped with adaptive cruise control systems (ACC-AVs) on longitudinal road profiles from the perspective of vehicle dynamics. Firstly, a co-simulation platform integrating PreScan, CarSim, and Simulink software is established, providing a comprehensive environment for simulating AV behavior. Secondly, an evaluation system is developed to assess AV’s feasibility on longitudinal roads, based on safety indicators (rear-end collisions occurrence) and comfort indicators (axial acceleration, vertical acceleration, and vertical acceleration change rate). Lastly, the feasibility of ACC-AVs on existing longitudinal profile roads is simulated and evaluated. The results indicate that, on straight slope section, ACC-AVs may experience rear-end collisions on downhill sections with design speeds below 100 km/h; when safety requirements are met, both uphill and downhill sections exhibit good comfort levels. For the vertical curve section, comfort is also favorable in segments with low design speeds and large vertical curve radii, however, as curve radii decrease or design speeds increase, comfort deteriorates. The findings of this study provide a reference for optimizing highway profile design for AVs.
Li, Zezhou, Cai, Mingmao, Gu, Tianqi, Yu, Bin
Analysis of Speeding and Crashes on Bridges in Mugling to Narayanghat Highway Segment in Nepal09-13-01-00023/3/2025
Driving speed affects road safety, impacting crash severity and the likelihood of involvement in accidents on highway bridges. However, their impacts remain unclear due to inconsistent topography and consideration of crash types. This study aimed to identify the status of accidents and factors associated with accidents occurring on bridges along the Mugling to Narayanghat highway segment in Nepal. The study area involves the selected highway segment stretching from Aptari junction (CH: 2+42) to Mugling junction (CH: 35+677). Spanning 33.25 km, the road traverses through both hilly and Terai regions. The study employs descriptive and correlation statistics to analyze crash data from 2018 to 2023, aiming to achieve its research objectives. The study reveals overspeeding as the primary cause of crashes, notably head-on and rear-end collisions. Two-wheelers frequently exceed the speed limit of 40 km/h limit (29–88 km/h), and four-wheelers do similarly (18–81 km/h), leading to overspeeding crashes. Trucks are most involved in incidents, followed by microbuses and cars. Head-on collisions dominate at bridges, followed by rear-end, sideswipe, and runoff collisions. Multivehicle incidents outnumber single-vehicle ones. Damaged railings, barriers, and guardrails significantly contribute to severe accidents, necessitating urgent repairs and new installations for improved bridge safety. Poor road conditions and roadside hazards also worsened dangers, highlighting the importance of road infrastructure maintenance and speed limit enforcement.
Giri, Om Prakash, Shahi, Padma Bahadur, Kunwar, Deepak Bahadur
Validating Human Factors-Based Classification Models for Safe and Efficient Mixed-Autonomy Interactions at Intersections Using a Virtual Simulator12-08-02-00192/12/2025
The introduction of autonomous vehicles (AVs) promises significant improvements to road safety and traffic congestion. However, mixed-autonomy traffic remains a major challenge as AVs are ill-suited to cooperate with human drivers in complex scenarios like intersection navigation. Specifically, human drivers use social cooperation and cues to navigate intersections while AVs rely on conservative driving behaviors that can lead to rear-end collisions, frustration from other road users, and inefficient travel. Using a virtual driving simulator, this study investigates the use of a human factors-informed cooperation model to reduce AV reliance on conservative driving behaviors. Four intersection scenarios, each involving a left-turning AV and a human driver proceeding straight, were designed to obfuscate the right-of-way. The classification models were trained to predict the future priority-taking behavior of the human driver. Results indicate that AVs employing the human factors-informed model were able to navigate the mixed-autonomy intersection scenarios significantly more efficiently without affecting safety or rider comfort when compared to a baseline, cautious AV. Overall, this research contributes to improved mixed-autonomy interactions and provides evidence for the importance of cooperation between AVs and human-driven vehicles.
Ziraldo, Erika, Oliver, Michele
Integration of Muscle Pre-tension and Activation to Evaluate Neck Muscle Strain Injury Risk during Simulated Rear Impacts Using a Finite Element Neck Model2025-22-00012/7/2025
Correia, Matheus A., McLachlin, Stewart D., Cronin, Duane S.
Development and Numerical and Experimental Validation of an Anti-Intrusion Device for Protecting the Battery Compartment in Electric Buses2024-36-009112/20/2024
The behavior of mechanical structures subjected to impacts is a topic of great relevance, with one of its applications being in the context of collisions on urban roads. According to data obtained from the electric bus monitoring platform E-Bus Radar, the fleet of vehicles with this means of propulsion has grown significantly in the last 6 years. Just from 2022 to 2023, the growth was 51%, jumping from 2669 to 4020 registered vehicles in Latin America. In this context, the present study investigated the behavior of the rear structure of an electric bus - EB in a rear-end collision scenario. The study of this region was motivated by the fact that it houses 4 out of the 12 battery packs and other electrical components. The main objective of this work is to evaluate the efficiency of the anti-intrusion and impact absorption mechanism to ensure the integrity of the batteries. Since damage in a collision can release different types of flammable electrolytes and even trigger a fire, posing a significant risk to passengers and other individuals near the vehicle in addition to its high added value. A module of the rear structure of the bus was manufactured and tested numerically and experimentally based on the pendulum test according to Resolution No. 629 of CONTRAN. The anti-intrusion device proved effective in protecting the batteries and racks, meeting the proposed approval criterion of preventing any component of the structure from contacting the batteries during impact. Subsequently, after calibrating the simulation with the rear module of the structure, the entire bus was discretized and numerically simulated for impact against a standardized rigid barrier and a numerical model of a light vehicle, both colliding with the rear of the electric vehicle at 50 km/h, where the anti-intrusion mechanism also proved effective. Finally, the experimental rear impact test of the complete bus versus an SUV also succeeded in ensuring the safety of the batteries.
Menino, Bruno G., Sordi, Alexsandro, Braida, Claudio A. B., Biondo, Felipe, Spengler, Felipe, Magnabosco, Guilherme
Intracranial Displacements due to Blunt Force Impact in a Postmortem Human Surrogate Brain09-12-02-001111/12/2024
Prevention and diagnosis of traumatic brain injuries (TBI) are reliant on understanding the biomechanical response of the brain to external stimuli. Finite element models (FEM) and artificial head surrogates are becoming a common method of investigating the dynamic response of the brain to injurious impact and inertial stimuli. The accuracy and validity of these models is reliant on postmortem human subject (PMHS) research to produce biofidelic brain tissue responses. Previous PMHS research has been performed to measure intracranial pressures, displacements, and strains when subjected to impact and inertial loading; however, there remains a need for additional PMHS datasets to improve our understanding of the brain’s dynamics. The purpose of this study is to measure the relative brain–skull displacement in a PMHS specimen when subjected to blunt force impacts. A high-speed X-ray (HSXR) imaging system and embedded radiopaque elastomeric markers were used to record PMHS impacts at varying impact velocities for two specimens: specimen CO-108 was subjected to a series of frontal impacts and specimen CO-109 was subjected to a series of rear impacts. Brain–skull relative deformation in each specimen indicates that brain deformation is dependent both on anatomical regions and of impact direction.
Demiannay, Jean-Jacques, Rovt, Jennifer, Brannen, MacKenzie, Xu, Sheng, Kang, Gia, Yip, Ashley, Azadi, Amir Hossein, Dehghan, Parisa, Goodwin, Shannon, Taylor, Reggie, Poon, Katherine, Brien, Susan, Hoshizaki, Blaine, Karton, Clara, Petel , Oren
Neck Injury Risk in Out-of-Position Rear Impact Scenarios Using a Reference Geometry-Based Head Repositioning09-12-02-002011/12/2024
Rear-end vehicle collisions may lead to whiplash-associated disorders (WADs), comprising a variety of neck and head pain responses. Specifically, increased axial head rotation has been associated with the risk of injuries during rear impacts, while specific tissues, including the capsular ligaments, have been implicated in pain response. Given the limited experimental data for out-of-position rear impact scenarios, computational human body models (HBMs) can inform the potential for tissue-level injury. Previous studies have considered external boundary conditions to reposition the head axially but were limited in reproducing a biofidelic movement. The objectives of this study were to implement a novel head repositioning method to achieve targeted axial rotations and evaluate the tissue-level response for a rear impact condition. The repositioning method used reference geometries to rotate the head to three target positions, showing good correspondence to reported interverbal rotations. Under a 7 g rear impact scenario, the head-turned models were compared with the neutral position and demonstrated increases in the maximum capsular ligament distractions. Increased head rotation was associated with increased ligament distractions. The locations with critical ligament distractions shifted to the lower cervical spine (below C3) and lateral portion of the capsular ligaments for the head-turned position cases. The proposed repositioning method introduced in this study enabled the model to achieve steady head rotations with realistic cervical spine movements, increasing the biofidelity of out-of-position rear impact simulations.
Reis, Matheus Seif, Cronin, Duane
Effects of Head Restraint (HR) Interference on Child Restraint System (CRS) Performance in Frontal and Far-Side Impacts2024-22-000310/10/2024
Forward-facing child restraint systems (FF CRS) and high-back boosters often contact the vehicle seat head restraint (HR) when installed, creating a gap between the back surface of the CRS and the vehicle seat. The effects of HR interference on dynamic CRS performance are not well documented. The objective of this study is to quantify the effects of HR interference for FF CRS and high-back boosters in frontal and far-side impacts. Production vehicle seats with prominent, removeable HRs were attached to a sled buck. One FF CRS and two booster models were tested with the HR in place (causing interference) and with the HR removed (no interference). A variety of installation methods were examined for the FF CRS. A total of twenty-four tests were run. In frontal impacts, HR interference produced small but consistent increases in frontal head excursion and HIC36. Head excursions were more directly related to the more forward initial position rather than kinematic differences caused by HR interference. In far-side impacts, HR interference did not have consistent effects on injury metrics. Overall, these results suggest only slight benefits of removing the HR in frontal impacts specifically. Caregivers should use caution if removing a vehicle HR to ensure that the current child occupant and all future vehicle occupants have adequate head support available in case of a rear impact.
Mansfield, Julie A.
Comprehensive Study on Challenges to Introduce Autonomous Emergency Braking (AEBS) Feature in Indian Perspective2024-01-30509/8/2024
India is a diverse country in terms of road conditions, road maintenance, traffic conditions, traffic density, quality of traffic which implies presence of agricultural tractors, bullock carts, autos, motor bikes, oncoming traffic in same lane, vulnerable road users (VRU) walking in the same lanes as vehicles, VRU’s crossing roads without using zebra crossings etc. as additional traffic quality deterrents in comparison to developed countries. The braking capacity of such vivid road users may not be at par with global standards due to their maintenance, loading beyond specifications, driver behavior which includes the tendency to maintain a close gap between the preceding vehicle etc. which may lead to incidents specifically of rear collisions due to the front vehicle going through an emergency braking event. The following paper provides a comprehensive study of the special considerations or intricacies in implementation of Autonomous Emergency Braking (AEBS) feature into Indian traffic perspective. The paper provides a comparison of the AEBS standard between Indian and EU markets. The paper provides the differences in traffic quality of Indian roads in comparison with EU to justify the limitations to be dealt with and eventually this paper also provides a detailed study on the special considerations to be inculcated in developing such feature specific to Indian customer and to enhance the safety of occupant as well as other road users.
Kartheek, Nedunuri, Khare, Rashmita, Sathyamurthy, Sainathan, Manickam, Praveenkumar, Kuchipudi, Venkata Sai Pavan
An Evaluation of the Performance of the Bendix Wingman Fusion G1 Collision Mitigation System in a 2017 Kenworth T6802024-01-28934/9/2024
The Bendix Wingman Fusion – a radar and camera collision mitigation system (CMS) available on commercial vehicles – was evaluated in two separate test series to determine its performance in simulated rear collision scenarios. In the first series of tests, evaluations were conducted in daytime, nighttime, and rainy conditions between 15 to 58 miles per hour (mph) to evaluate the performance of the audible and visual forward collision warning (FCW) system in a first-generation Bendix Wingman Fusion CMS while approaching a stationary live vehicle target (SLVT) in a 2017 Kenworth T680. A second test series was conducted with a 2017 Kenworth T680 traveling at 50 mph in daytime conditions approaching a decelerating vehicle to evaluate the Bendix Wingman Fusion CMS on the truck. Both test series sought to determine the maximum distance the system would warn prior to the test driver swerving around the SLVT or moving vehicle target. The first test series utilized a 2014 Ford F150 as the SLVT and the second test series utilized a 2014 Lexus RX350 as a Decelerating Vehicle Target. Testing measured the time to collision (TTC) values of the issuance of the audible/visual FCW utilizing VBOX data acquisition equipment. The results of the two series of tests provide valuable information about the performance of the Bendix Wingman Fusion CMS approaching stationary and decelerating vehicles in rear collision scenarios.
Harrington, Shawn, Martin, Nicholas, Leiss, Peter
Comparing Event Data Recorder Data (EDR) in Front/Rear Collisions from the Crash Investigation Sampling System (CISS) Database2024-01-28924/9/2024
The accuracy of collision severity data recorded by event data recorders (EDRs) has been previously measured primarily using barrier impact data from compliance tests and experimental low-speed impacts. There has been less study of the accuracy of EDR-based collision severity data in real-world, vehicle-to-vehicle collisions. Here we used 189 real-world front-into-rear collisions from the Crash Investigating Sampling System (CISS) database where the EDR from both vehicles recorded a severity to examine the accuracy of the EDR-reported speed changes. We calculated relative error between the EDR-reported speed change of each vehicle and a speed change predicted for that same vehicle using the EDR-reported speed change of the other vehicle and conservation of momentum. We also examined the effect of vehicle-type, mass ratio, and pre-impact braking on the relative error in the speed changes. Overall, we found that the common practice of using the bullet vehicle’s EDR-reported speed change to estimate the target vehicle’s speed change is reliable and can be adjusted for some vehicle types and mass ratios to improve the accuracy of the target vehicle’s estimated speed change. We also found that about 10-13% of EDR-reported speed changes may have errors larger than ±10%.
Fix, Ryan, Wilkinson, Craig, Siegmund, Gunter P.
Analysis of Occupants by Seating Location, Restraint Use and Injury Risk in Tow-Away Crashes2024-01-27524/9/2024
This study was conducted to assess the occupant restraint use and injury risks by seating position. The results were used to discuss the merit of selected warning systems. The 1989-2015 NASS-CDS and 2017-2021 CISS data were analyzed for light vehicles in all, frontal and rear tow-away crashes. The differences in serious injury risk (MAIS 3+F) were determined for front and rear seating positions, including the right, middle and left second-row seats. Occupancy and restraint use were determined by model year groups. Occupancy relative to the driver was 27% in the right-front (RF) and 17% in the second row in all crashes. About 39% of second-row passengers were in the left seat, 15% in the center seat and 47% in the right seat. Restraint use was lower in the second row compared to front seats. It was 43% in the right-front and 32% in the second-row seats in all crashes involving serious injury. Restraint use increased with model year groups. It was 63% in the ‘61-‘89 MY vehicles and 90% in the ‘10-‘22 MYs for drivers. The corresponding rate was 59% and 91% for right-front passengers, and 48% and 91% for second-row passengers. Overall, the injury risk was 2.59% ± 0.20% for drivers, 2.52% ± 0.16% for RF passengers and 1.70% ± 0.16% for second-row passengers in all crashes. The risk was significantly higher (p<0.001) for RF passengers than for second-row occupants in all crashes. Injury risks were significantly higher in RF passengers in frontal crashes (2.58% ± 0.20% v. 1.43% ± 0.24%, p<0.001) than second-row occupants, but lower in rear crashes (0.63% ± 0.15% v. 0.99% ± 0.20%, p>0.1). The injury risk was lowest in modern (‘10-‘22 MY) vehicles compared to other model years. For second-row occupants, the risk was highest in the right-rear seat in all crashes and in frontal crashes, at 1.91% ± 0.23% (1.45%-2.36% 95th CI) and 1.82% ± 0.49% (0.86-2.78 95th CI) respectively. The risk was 41% higher (p< 0.06, 0.75% diff with 0.21%-1.70% 95th CI) for right-rear than left-rear occupants in frontal crashes. The injury risks were similar in rear crashes. The rear seat is still the safest seating position overall, even with lower restraint use in rear seats. Current mandated warning systems to place children in the rear seat are relevant. Regulations, policies, seatbelt laws and test programs seem successful in increasing restraint use and reducing injury rates to front-and rear-seat occupants. Some have suggested adding a warning to place children behind empty front seats if possible. This would tend to move children to the right side of the vehicle as the left front seat is always occupied. However, the results from this study showed that the overall injury risk was higher in the right-rear seat than in the left. The results were however only statistically significant in frontal impacts.
Parenteau, Chantal, Burnett, Roger
Occupant Kinematics During Chain-Collisions: Discrete vs Combined Collisions2024-01-24894/9/2024
There is little prior research into chain-collisions, despite their relatively large contribution to injury and harm in motor-vehicle collisions. This study conducted a series of rear-impact, front-impact, and chain-collision impacts using a bumper car ride at an active amusement park as a proxy for automobiles. The purpose was to begin to identify the threshold time range when separate, discrete collisions transition into a hybrid or combined chain-collision mode and provide bases for future analyses. The test series consisted of rear impacts into an occupied target vehicle from a driven bullet vehicle; frontal impacts into a perimeter barrier (wall); chain-collisions consisting of a driven bullet vehicle striking an occupied primary target vehicle, which then collided with a non-occupied secondary target vehicle; and chain-collisions consisting of a driven bullet vehicle striking an occupied primary target vehicle which then collided with a wall. Time between collisions was adjusted via spacing. Vehicle impact velocities, changes in velocity (delta-Vs), accelerations, and coefficients of restitution are reported. Head and extremity excursions of the restrained occupant of the primary target vehicle were also tracked using high-speed video recording. The results show that chain-collisions exhibited three phases: an early phase that occurs during the initial rearward occupant excursion, a middle phase that occurs during the forward rebound occupant excursion, and a late phase that occurs while the occupant is recovering back to the initial position. The first phase appears to last for approximately 150 ms, the middle phase for approximately 50 to 75 ms, and the late phase from thereafter until approximately 400 ms to 500 ms after the initial collision. The middle phase appears to be related to the timing of the occupant’s return to their original position and their maximum rebound velocity and the late phase to the remaining occupant displacement but not velocity. Overall, occupant and vehicle kinematics during a chain-collision were different from those of the individual component collisions and were different from a superposition of the component collisions. This is the first reporting of these phases in a chain-collision.
Bussone, William R., Koiler, Reza, Benda, Jamie, Carney, Nicholas, Geffard, Andres, Sam, Samantha
Study of Indian Road Traffic Accident Characteristics Using Clustering Analysis2024-01-27544/9/2024
In 2021, 412,432 road accidents were reported in India, resulting in 153,972 deaths and 384,448 injuries. India has the highest number of road fatalities, accounting for 11% of the global road fatalities. Therefore, it is important to explore the underlying causes of accidents on Indian roads. The objective of this study is to identify the factors inherent in accidents in India using clustering analysis based on self-organizing maps (SOM). It also attempts to recommend some countermeasures based on the identified factors. The study used Indian accident data collected by members of ICAT-ADAC (International Centre for Automotive Technology - Accident Data Analysis Centre) under the ICAT-RNTBCI joint project approved by the Ministry of Heavy Industries, Government of India. 210 cases were collected from the National Highway between Jaipur and Gurgaon and 239 cases from urban and semi-urban roads around Chennai were used for the analysis. Based on this study, the following results were obtained from (i) Macro Analysis: Accidents on straight roads occur at uncontrolled intersections due to excessive speed. In rugged terrain, accidents occur in rainy and foggy environmental conditions. (ii) From micro analysis - National Highway: Lack of underride guard bars/non-standard guard bars cause serious rear-end crashes, non-use of seat belts in large vehicles increases the likelihood of fatal crashes. One-way divider cuts, rumble strips, safer pedestrian infrastructure, use of roadway lighting, and signage are effective in reducing fatal crashes. The results of this study will help transportation authorities and relevant government policymakers make the necessary decisions to improve road traffic safety.
Vimalathithan, Kulothungan, Rao K M, Pranesh, Vallabhaneni, Pratapnaidu, Selvarathinam, Vivekraj, Manoharan, Jeyabharath, Pal, Chinmoy, Padhy, Sitikantha, Joshi, Madhusudan
The Effectiveness of Forward Collision Warning Systems in Detecting Real-World Passenger and Nonpassenger Vehicles Relative to a Surrogate Vehicle Target2024-01-19784/9/2024
Automatic emergency braking and forward collision warning (FCW) reduce the incidence of police-reported rear-end crashes by 27% to 50%, but these systems may not be effective for preventing rear-end crashes with nonpassenger vehicles. IIHS and Transport Canada evaluated FCW performance with 12 nonpassenger and 7 passenger vehicle or surrogate vehicle targets in five 2021-2022 model year vehicles. The presence and timing of an FCW was measured as a test vehicle traveling 50, 60, or 70 km/h approached a stationary target ahead in the lane center. Equivalence testing was used to evaluate whether the proportion of trials with an FCW (within ± 0.20) and the average time-to-collision of the warning (within ± 0.23 sec) for each target was meaningfully different from a global vehicle car target (GVT). A similar approach was used to determine if FCW performance was reproducible between 3 targets tested by both IIHS and Transport Canada and was equivalent between surrogate car and motorcycle targets produced by different companies. FCW systems provided fewer and later warnings when the vehicles approached nonpassenger vehicles compared with the GVT. Results were reproducible between IIHS and Transport Canada, but FCW performance with passenger car and motorcycle surrogate targets representing the same vehicle were not always equivalent. Testing organizations should evaluate AEB and FCW systems with nonpassenger vehicle targets to ensure that AEB and FCW performance observed with passenger vehicles extends to other vehicle types, particularly motorcycles and medium or large trucks that are commonly struck in fatal rear-end crashes.
Kidd, David, Anctil, Benoit, Charlebois, Dominique
Enhanced Safety of Heavy-Duty Vehicles on Highways through Automatic Speed Enforcement – A Simulation Study2024-01-19644/9/2024
Highway safety remains a significant concern, especially in mixed traffic scenarios involving heavy-duty vehicles (HDV) and smaller passenger cars. The vulnerability of HDVs following closely behind smaller cars is evident in incidents involving the lead vehicle, potentially leading to catastrophic rear-end collisions. This paper explores how automatic speed enforcement systems, using speed cameras, can mitigate risks for HDVs in such critical situations. While historical crash data consistently demonstrates the reduction of accidents near speed cameras, this paper goes beyond the conventional notion of crash occurrence reduction. Instead, it investigates the profound impact of driver behavior changes within desired travel speed distribution, especially around speed cameras, and their contribution to the safety of trailing vehicles, with a specific focus on heavy-duty trucks in accident-prone scenarios. To conduct this analysis, we utilize SUMO, an open-source microscopic traffic simulator, enabling realistic simulations of real-world driving behaviors with and without speed cameras. The simulations also consider empirical distributions of desired headway gaps and reaction times exhibited by human drivers. This study offers a fresh perspective on highway safety by examining how the influence of automatic speed enforcement systems on driver behavior enhances the safety of HDV when faced with challenging situations. By shedding light on these dynamics, we contribute valuable insights to the ongoing research efforts on using technology to create safer roadways, ultimately promoting safer coexistence between heavy-duty and passenger vehicles.
Shiledar, Ankur, Sujan, Vivek, Siekmann, Adam, Yuan, Jinghui
Seatback Failures and Human Tolerance in Severe Rear Impacts2024-26-00031/16/2024
Seatback and head restraints are the primary restraining devices in rear-impact collisions. The seatback failures expose front seat occupants to dive deep into the rear compartment survival space. Furthermore, it allows the occupants to get in a position with lower spinal tolerance to the impact direction. This paper employs sled tests to demonstrate the dangers of seatback failures in severe rear impact by allowing the occupants to orient their spine in its lowest tolerance zone to the impact direction. Furthermore, the sled test shows the potential of head pocketing phenomena and torso augmentation producing compressive cervical spine loading enough to cause first-order neck buckling. Finally, the results of collapsing seatback dynamics are compared to the strong seatback performance by conducting a similar test with a strong ABTS seatback. The study demonstrates that the strong seatbacks in severe rear impacts produce favorable outcomes while keeping the occupant in their higher spinal tolerance zone to the impact direction.
Thorbole, Chandrashekhar
Child Injury Pattern and Mechanism Differences Based on the Front Seat Occupancy Status in Rear Impacts with Severe Structural Intrusions from the Rear2024-26-00051/16/2024
Child crash injury protection in severe rear impact chiefly depends on how well the rear survival space bounded by the vehicle structure is maintained. Previous research and studies have shown the ill effects of front seatback collapse intruding into the rear child survival space from front with minor or no intrusions from the rear. This paper shows the child injury pattern and fatal injury mechanism for a rear impact crash with a severe compartment intrusion from the rear without any front seat occupant. Furthermore, it compares the injury outcome with a similar crash and severe intrusion in the presence of the front occupant employing a full-scale vehicle-to-vehicle crash test. A detailed real-world crash investigation is conducted to identify the injury mechanism and is compared with the outcome of similar severity rear impact vehicle-to-vehicle crash tests producing different injury patterns. The comparison and the analysis show that the survival space intrusion due to safety cage collapse from the rear is the most significant factor in the presence or absence of the front seat occupant. The injury pattern changes with the same overall critical outcome. If the safety cage collapse intrusion and front seat occupancy are considered as two factors modulating the response of the injury pattern, then there is a significant interaction of these factors modulating the response.
Thorbole, Chandrashekhar
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