Crash Configurations Research Articles

Bridging the gap: Mechanistic-based cyclist injury risk curves using two decades of crash data

Objective Injury risk curves are vital in quantifying the relative safety consequences of real-world collisions. Previous injury risk curves for bicycle-passenger vehicle crashes have predominantly focused on frontal impacts. This creates a gap in cyclist injury risk assessment for other geometric crash configurations. The goal of this study was to create an “omnidirectional” injury risk model, informed by known injury causing mechanisms, that is applicable to most geometric configurations. Methods We used data from years 1999–2022 of the German In-Depth Accident Study (GIDAS). We describe the pattern of injuries for cyclists involved in collisions with passenger vehicles, and we developed injury risk functions at various AIS levels for these collisions. A mechanistic-based approach accounting for biomechanically-relevant variables was used to select model parameters a priori. Cyclist age (including children) and sex were regarded as relevant predictors of injury risk. Speed and impact geometry were captured through a novel predictor, Effective Collision Speed, which transforms the vehicle and cyclist speeds into a single value and incorporates frictional considerations observed during side engagements. Cyclist engagement with the vehicle was captured with a variable demonstrating the potential for a normal projection. We additionally present analyses weighted toward German nationwide data. Results We identified 6,576 cyclists involved in collisions with passenger vehicles. AIS3+ cyclist injuries occurred most often in the head, thorax, and lower extremities. Effective Collision Speed was a strong predictor of injury risk. Collisions with a potential for a normal projection were associated with increased risk, though this was only significant at the MAIS2+F severity level. Younger children had slightly higher injury risk compared to young adults, while elderly cyclists had the highest risk of AIS3+ injury. Sex was a significant predictor only for the MAIS2+F injury risk curves. Significance U.S. cyclist fatalities increased 55% from 2010 to 2021. To reduce injuries and fatalities, it is crucial to understand cyclist injury risk. This study builds on previous analyses by including children, incorporating additional mechanistic predictors, broadening the scope of included crashes, and using weighting to generalize these estimates toward national German statistics.

Influence of car front-end designs on motorcyclists’ trajectory in head-on and side-on-head crashes

Motorcyclists are highly vulnerable road users, and cars are one of their primary crash opponents. This study investigates the influence of car front-end designs on motorcyclist trajectory in head-on and side-on-head crashes. The analysis is based on a dataset of 120 multi-body crash simulations conducted using MADYMO and post-processed with MATLAB. An analysis of 1412 real-world Powered Two-Wheeler (PTW) to car accidents was conducted to determine the most common crash configurations and the associated ranges of the variables, such as vehicle speeds and contact points. Three PTW styles (sport-touring, scooter, and sport) and four car front-end designs (Sport utility vehicle (SUV), Family Car/Sedan (FCR), Roadster (RDS), and Multi-purpose vehicle (MPV)) were considered.The study examined the riders’ thrown distance in both collision types. It was observed that, regardless of the collision type, the head was identified overall as the primary body region coming into contact with the opposing vehicle, followed by the chest and neck. In frontal collisions, an augmented bonnet height corresponded to an increased incidence of head contact, whereas a lower bonnet height resulted in a higher frequency of chest contact. Moreover, the thrown distance depended also on PTW speed, particularly for sport and sport-touring motorcycles. Notably, contact with the car windscreen was only observed at velocities exceeding 60 km/h, whereas impact with the bonnet leading edge occurred exclusively below this threshold. Due to the shielding effect of their PTW’s fairing, scooter riders predominantly experienced no contact with the opposing vehicle. Sport-touring motorcycles exhibited a more vertical trajectory upon ejection, leading to a greater likelihood of overturning and subsequent rearward head impact with the vehicle. In contrast, sport motorcycles tended to forward projections with a high likelihood of chest contact. In the case of lateral impacts, it was observed that vehicles with a more prominent profile, such as SUVs and MPVs, equipped with protruding bumpers, effectively restrained riders. In this case, vehicle speed did not exert a significant influence on the thrown distance. Additionally, the presence of a conspicuous fuel tank and the initial posture of the rider on the PTW played a crucial role in determining the final thrown distance. Due to their upright postures and the absence of a pronounced fuel tank, scooter dummies were thrown further than others, thus causing head contact with the windscreen.These findings highlight the importance of car front-end design and PTW fairings in mitigating riders’ injuries and provide valuable insights to vehicle manufacturers for developing tailored safety measures for riders.

Real-world crash configurations and traffic violations among newly licensed young drivers with different route familiarity levels

Objective Young drivers aged 24 and below are at heightened risks of being influenced by their route familiarity levels. This study aims to compare prevalences of crash culpability, crash configurations and risky driver behaviors among newly licensed young drivers when they are driving on roads with different route familiarity levels. Methods Based on the road traffic crash and violation data in Yunnan Province of China from January 2017 through December 2019, we classified drivers’ different route familiarity levels by utilizing spatial distance away from residence-based method, including driving on high route familiarity (HRF) and low route familiarity (LRF) roads. Prevalence ratios were estimated using generalized estimating equation log-binomial regression models. Results We identified 12016 newly licensed young drivers driving on HRF roads and 2189 drivers on LRF roads. Within 48 months of licensure, young drivers on LRF roads were more likely to be at fault for their motor vehicle crashes than those on HRF roads. Young drivers on LRF roads were more likely to be with failure to obey traffic control device, with failure to yield right of way, wrong way driving, backing unsafely and improper parking compared with those on HRF roads. Drivers on LRF roads were less likely to be inattentive and driving with unsafe speed and following too closely compared with those on HRF roads. Conclusions Several basic aspects of targeted countermeasures can be put forward. Visual impacts such as rectangular rapid-flashing beacon (RRFB) can be used in order to prevent wrong way driving on the tourist roadways. Arranging safety talks and programs in colleges and universities and technical interventions like Advanced Driver Assistance Systems (ADAS) can be used to reduce young drivers’ driving distraction and overconfidence. It is recommended that the driving schools can use these research findings to include in licensure program to make young drivers more aware of the various factors that expose them to crash risks so that more defensive driving may be needed under different situations, and this can also help build the graduated driving licensure (GDL) programme in China.

Preliminary evaluation of a passive safety device concept for the protection of riders

Powered Two-Wheeler riders are over-represented in crash statistics worldwide, and currently available safety solutions have not triggered a decreasing trend. A new device concept, comprised of a wearable vest with belt stripes sewn on the back and fastened to the motorcycle frame through a metal cable, was developed to save riders’ lives. The objective of this paper is the evaluation of its protective effectiveness in a set of representative crash configurations selected from the ISO 13232 database. The configurations were reproduced in a multibody environment, and each of them was characterised through the following parameters: the impact speeds, contact points, relative heading angle, and the Boolean presence of the safety device. The preliminary evaluation revealed encouraging outcomes as several body regions reported reduced injury indices. However, the benefits depended on the speed range and impact configuration. Overall, the benefits outweighed the additional risks in the selected accident database.

Determination of functional scenarios for intersection collisions

IntroductionThe National Highway Traffic Safety Administration (NHTSA) estimated that in 2019, intersection crashes accounted for $179 billion of economic damages and $639 billion in societal damages. Intersection advanced driver assist systems (I-ADASs) and automated driving systems (ADS) are designed and have been actively deployed to avoid or mitigate these intersection crash scenarios. Given the indeterminate parameter space for describing collision scenarios, evaluators, and designers are all challenged with condensing the possible intersection crash configurations into digestible, executable conditions for scenario-based simulation testing. The objective of this study is to identify functional intersection crash configurations for I-ADAS and ADS safety evaluation. MethodsReal-world intersection crash characteristics are important considerations for scenario testing as these features can directly correlate to or influence causality, controllability, and potential injury severity. To identify functional intersection crash types, similar crash scenarios were grouped together by identified critical features using an unsupervised decision tree model. A key advantage of this approach was that the implemented cluster crash scenarios would be understandable and interpretable by users. Unsupervised decision trees work by generating uniformly distributed synthetic data with features from real data and classifying all the data as real or synthetic. Long, non-diverging branches were manually pruned to reduce overfitting and improve model performance. Feature importance values were computed based on how effective a given variable grouped the crashes together. Data sourcesThis analysis selected intersection cases that only involved two vehicles from the Crash Investigation Sampling System (CISS) spanning 2017 to 2020. Crash features such as road geometry, intersection signal, and vehicle configuration were important to consider for scenario generation. CISS contained the traffic device, device functionality, vehicle intended pre-event movement, road alignment, road profile, trafficway flow, number of lanes, and crash type for each crash case. Intersection geometry, intersecting road angle, each vehicles’ legal moves, and the presence of a two-way-left-turn-lane (TWLTL), channelized roads, bike lanes, crosswalks, street parking, slip lanes, and visual obstructions were manually recorded from the scene diagram. ResultsThe tree identified 44 functional intersection crash configurations after pruning. These clusters have five main sections: Straight-crossing path (SCP) crashes at 4-legged intersections, Left-Turn-Across-Path/Opposite Direction (LTAP/OD) crashes at 4-legged intersections, other crash types at 4-legged intersections, roundabout and multileg intersections, and 3-legged intersection crashes. The features that best split the data were TWLTL, lane travel direction violation, and traffic control device functionality. The largest cluster was SCP crashes at 4-legged, undivided intersections where the traffic control device was working and both vehicles did not violate the direction of their lane of travel. This cluster was adjacent to 32 vehicles in similar SCP crashes except a vehicle performed an unexpected maneuver based on their lane position. ConclusionThese 44 identified crash configurations could be useful in bolstering the robustness of I-ADAS and ADS intersection scenario testing as they are a compact representation of all the police reported intersection crashes where a vehicle was towed. Future studies could generate logical scenarios with distributions of initial conditions and behaviors from these clusters that could be used to evaluate an I-ADAS or ADS.

Analyzing driver injury severity in two-vehicle rear-end crashes considering leading-following configurations based on passenger car and light truck involvement

Rear-end crash is a major type of traffic crashes leading to a large number of injuries and fatalities each year, and passenger cars and light trucks are two main vehicle types in rear-end crashes on US roadways. Passenger cars and light trucks are different in size, vehicle mass and driver’s vision. It is necessary to investigate the driver injury outcome patterns in rear-end crashes between passenger cars and light trucks considering crash configurations regarding the leading and following vehicle types. This study employs latent class multinomial logit (MNL) model to examine the risk factors on driver injury severity along with heterogeneity in variable effects presented by the cluster pattern in two-vehicle rear-end crashes involving passenger cars and light trucks, considering four crash configuration types, i.e., a passenger car struck by a passenger car, a light truck struck by a light truck, a passenger car struck by a light truck, and a light truck struck by a passenger car as exploratory variables. A model with two latent classes, which indicates the heterogeneity in variable effects among all the observations, is found to best fit the 7-year crash dataset from Washington State. The pseudo-elasticities are calculated to quantify the marginal effects of the contributing factors. The risk factors curve and sloping road condition, driver without seatbelt, and driver age of 65 and above increase driver fatality and serious injury risk greatly, and these three factors contribute from different latent classes. The crash configuration of a passenger car struck by a light truck is found to be one of class characteristics factors, which indicates that the heterogeneity exists between these two vehicle types. This factor is also a risk factor of injury. Furthermore, the leading vehicle is found to be much more vulnerable and closely related to injury, especially when it is in the crash of a passenger car struck by a light truck. The latent classes discovered give theoretical evidence of how to appropriately select subset data for further model construction for practical interest of serious injury prevention. The risk factors and their influence on injury severity provide beneficial insights on developing relevant countermeasures and strategies for injury severity mitigation on rear-end crashes involving passenger cars and light trucks.

Impact Area and Speed Effects on Powered Two-Wheeler Crash Fatality and Injury Risk

<div>The primary objective of this study was to evaluate the fatality risk of powered two-wheeler (PTW) riders across different impact orientations while controlling for different opponent vehicle (OV) types. For the crash configurations with higher fatality rate, the secondary objective was to create an initial speed–fatality prediction model specific to the United States. Data from the NHTSA Crash Reporting Sampling System and the Fatality Analysis Reporting System from 2017 to 2020 was used to estimate the odds of the different possible vehicle combinations and orientations in PTW–OV crashes. Binary logistic regression was then used to model the speed–fatality risk relationship for the configurations with the highest fatality odds. Results showed that collisions with heavy trucks were more likely to be fatal for PTW riders than those with other OV types. Additionally, the most dangerous impact orientations were found to be those where the PTW impacted the OVs front or sides, with fatality odds, respectively, four and five times higher than when the OV rear-end was impacted. The high variability in the odds of different crash configurations suggests the importance of considering the impact orientation factor in future injury prediction models. The speed–fatality prediction models developed for head-on and side crashes could provide an initial tool to evaluate the effectiveness of advanced rider assistance systems and other safety countermeasures in the United States, particularly those that result in speed reductions.</div>

Evaluation of intersection crashes using naturalistic driving data through the lens of future I-ADAS

Objective Intersection advanced driver assistance systems (I-ADAS) with the capability to detect possible collisions and perform evasive braking have the potential to reduce the number of intersection crashes. However, these systems will encounter many challenges caused by the complexity of real-world driving conditions. The purpose of this study is to use real-world naturalistic driving data to conduct an initial exploration of the potential challenges for future I-ADAS in straight crossing path (SCP), left turn across path/lateral direction (LTAP/LD), and left turn across path/opposite direction (LTAP/OD) crash configurations. Methods Intersection crashes were selected from the Second Strategic Highway Research Program (SHRP 2) Naturalistic Driving Study. The SHRP 2 dataset includes front-facing, driver-facing, rear-facing, and a hands/feet-facing video and vehicle speed, steering, accelerator, and brake time-series data. This data was reviewed to understand driver sightline obstructions, driver distractions, and initiation of driver responses. The estimated time to collision (TTC) from the precipitating event, defined as when either vehicle entered the intersection without the right-of-way, was computed based on the distance to the impact point divided by the current velocity of the subject vehicle. Results The median impact speed was 18.0 km/h for SCP and LTAP/LD crashes and 16.1 km/h for LTAP/OD crashes. The median TTC from the precipitating event was 1.35 s for SCP and LTAP/LD crashes and 1.44 s for LTAP/OD crashes. For SCP crashes, the three main sightline obstruction scenarios were slower vehicles traveling in the same direction waiting to turn right, vehicles in the closer crossing lane, and a parked truck. For LTAP/OD crashes, the sightline obstruction was often oncoming vehicles in a closer lane blocking the view of another vehicle. Conclusion Sightline obstructions could present a challenge for future I-ADAS to activate in SCP, LTAP/LD, and LTAP/OD crashes. This study utilized naturalistic driving data to complete a comprehensive analysis of intersection crashes, including driver distractions, evasive maneuvers, and sightline obstructions that can assist in the development of I-ADAS. This analysis is not possible with police-reported crash data only, which does not contain necessary details on the driver and surrounding environment.

Enhanced Aggregate Framework to Model Crash Frequency by Accommodating Zero Crashes by Crash Type

In recent years, joint count and fractional split model structure based approaches have emerged as a credible alternative for multivariate crash frequency dependent variables. However, current approaches in the fractional split theme have a limitation. The fractional split component of these frameworks allocates a proportion to all crash configurations. It is possible that, across spatial units, several crash configurations might have a large share of zero crashes. In the traditional multivariate context, in the presence of a high share of zeros, researchers employ zero-inflated or hurdle variants such as the zero inflated negative binomial model. The current research effort improves the fractional split based multivariate model systems with an explicit consideration for the potential presence of zeros by crash configuration. The newly included binary component can be employed to identify safer (or riskier) zones by crash configuration. The framework also accommodates unobserved heterogeneity across the components of the model system. The proposed model structure is estimated using zonal data from the Central Florida region, U.S., for 2016. The model considered six crash types—rear-end, angle, sideswipe, single-vehicle, multi-vehicle (three or more), and non-motorized crashes. The model estimation is conducted using an exhaustive set of independent variables. The model results clearly highlight the importance of accommodating zero crashes by crash type in the analysis. The model exercise is further augmented with a validation analysis.

Motorcycle emergency steering assistance: A systematic approach from system definition to benefit estimation and exploratory field testing

Braking assistance systems are already contributing to improving motorcyclists’ safety, however, research on emergency systems acting on the steering is lacking. These systems, already available for passenger cars, could prevent or mitigate motorcycle crashes in which safety functions based only on braking are ineffective. The first research question was to quantify the safety impact of diverse emergency assistance systems acting on the steering of a motorcycle. For the most promising system, the second research question was to assess the feasibility of its intervention using a real motorcycle.Three emergency steering assistance systems were defined in terms of Functionality, Purpose, and Applicability: Motorcycle Curve Assist (MCA), Motorcycle Stabilisation (MS), and Motorcycle Autonomous Emergency Steering (MAES). Experts evaluated each system’s applicability and effectiveness based on the specific crash configuration (using Definitions for Classifying Accidents — DCA), the Knowledge-Based system of Motorcycle Safety (KBMS), and the In-Depth Crash Reconstruction (IDCR). An experimental campaign was conducted with an instrumented motorcycle to assess the rider’s reaction to external steering input. A surrogate method for an active steering assistance system imparted external steering torques in correspondence with a lane change to analyse the effect of the steering inputs on motorcycle dynamics and rider controllability.MAES globally got the best score for each assessment method. MS received better evaluations than MCA in two out of three methods. The union of the three systems covered a sizeable fraction of the crashes considered (maximum score in 22.8% of the cases). An estimation of the injury potential mitigation, based on injury risk functions for motorcyclists, was made for the most promising system (MAES). The field test data and video footage showed no instability or loss of control, despite the high intensity (>20Nm) of the external steering input. The rider interviews confirmed that the external action was intense but manageable.For the first time, this study presents an exploratory assessment of the applicability, benefits, and feasibility of motorcycle safety functions acting on the steering. MAES, in particular, was found applicable to a relevant share of crashes involving motorcycles. Remarkably, applying an external action to produce a lateral avoidance manoeuvre proved feasible in a real-world test setting.

Influences of human thorax variability on population rib fracture risk prediction using human body models.

Rib fractures remain a common injury for vehicle occupants in crashes. The risk of a human sustaining rib fractures from thorax loading is highly variable, potentially due to a variability in individual factors such as material properties and geometry of the ribs and ribcage. Human body models (HBMs) with a detailed ribcage can be used as occupant substitutes to aid in the prediction of rib injury risk at the tissue level in crash analysis. To improve this capability, model parametrization can be used to represent human variability in simulation studies. The aim of this study was to identify the variations in the physical properties of the human thorax that have the most influence on rib fracture risk for the population of vehicle occupants. A total of 15 different geometrical and material factors, sourced from published literature, were varied in a parametrized SAFER HBM. Parametric sensitivity analyses were conducted for two crash configurations, frontal and near-side impacts. The results show that variability in rib cortical bone thickness, rib cortical bone material properties, and rib cross-sectional width had the greatest influence on the risk for an occupant to sustain two or more fractured ribs in both impacts. Therefore, it is recommended that these three parameters be included in rib fracture risk analysis with HBMs for the population of vehicle occupants.

Electric urban light vehicles structural integrity and occupant protection validation through experimental crash tests

Multi-Moby project, funded under H2020 n° 101006953, aims at developing technology for safe, efficient and affordable urban electric vehicles. The objective of the paper is to show the results achieved in relation to structural integrity and occupant protection in the first year of the project. In a first stage simulation tools have been used to optimise the vehicle structure crashworthiness at different crash configuration based on smart use of High Strength Steels focused to simplified and affordable manufacturing processes. Once the structural behaviour met requirements and expectations, the restraint system has been developed. After design optimisation, three vehicles have been prototyped to perform three crash tests, two of them frontal, corresponding to Regulation 137 and Regulation 94, and one lateral, corresponding to Regulation 95.

Can the speed limit be used as a surrogate for the striking vehicle’s travel speed or delta-V in police-reported rear-end crashes?

Objective: A recent study by Kidd (2022) recommended that organizations evaluating front crash prevention (FCP) systems like automatic emergency braking and forward collision warning increase speed differentials in existing test scenarios from 25 mph to 45 mph to make the tests more representative of police-reported rear-end crashes. Kidd used the posted speed limit as a proxy for the striking vehicle’s travel speed prior to the crash. The current study used velocity data from event data recorders (EDRs) in rear-end crashes to evaluate this assumption. These same data were used to replicate another study (Farmer 2003) that showed the speed limit was a poor surrogate for delta-V in rear-end crashes. Method: A total of 11,199 crash records during 2017–2020 were extracted from the Crash Investigation Sampling System database. The analysis was restricted to 436 of these records that involved two vehicles with a front-to-rear manner of collision or rear-end crash configuration with EDR data from the striking vehicle. The relationships between the posted speed limit and striking-vehicle travel speed and between the speed limit and delta-V were modeled using regression. Results: On average, the speed limit overestimated striking-vehicle travel speed by 2 mph, but the relationship between the speed limit and travel speed was not linear. The speed limit reasonably approximated travel speed on roads with speed limits of 30 and 50 mph or higher. It slightly overestimated travel speed on roads with 40–45 mph speed limits and underestimated it on roads with limits of 25 mph or less. The probability that the striking vehicle’s travel speed was 25 mph or less on any road was 0.09. In contrast, the probability of the striking vehicle’s travel speed being 45 mph or less was 0.54 overall and 0.75 or higher for roads with a speed limit between 25 and 45 mph. As found in prior research, there was no significant relationship between the speed limit and delta-V. Conclusion: The posted speed limit was a reasonable surrogate for the striking vehicle’s travel speed prior to police-reported rear-end crashes on roads with a speed limit above 25 mph. It was not a reasonable surrogate for delta-V. Travel speeds on roads with speed limits of 25 mph or less were much higher than the speed limit, which suggests that existing scenarios used to evaluate FCP system performance represent travel speeds in fewer police-reported rear-end crashes than previously thought. Increasing speed differentials in existing FCP test scenarios to 45 mph would reflect the striking vehicle’s travel speed in three quarters of rear-end crashes on roads with a speed limit of 45 mph or less.

Applicability Assessment of Active Safety Systems for Motorcycles Using Population-Based Crash Data: Cross-Country Comparison among Australia, Italy, and USA

The role of powered two-wheeler (PTW) transport from the perspective of a more sustainable mobility system is undermined by the associated high injury risk due to crashes. Motorcycle-based active safety systems promise to avoid or mitigate many of these crashes suffered by PTW riders. Despite this, most systems are still only in the prototype phase and understanding which systems have the greatest chance of reducing crashes is an important step in prioritizing their development. Earlier studies have examined the applicability of these systems to individual crash configurations, e.g., rear-end vs. intersection crashes. However, there may be large regional differences in the distribution of PTW crash configurations, motorcycle types, and road systems, and hence in the priority for the development of systems. The study objective is to compare the applicability of five active safety systems for PTWs in Australia, Italy, and the US using real-world crash data from each region. The analysis found stark differences in the expected applicability of the systems across the three regions. ABS generally resulted in the most applicable system, with estimated applicability in 45–60% of all crashes. In contrast, in 20–30% of the crashes in each country, none of the safety systems analyzed were found to be applicable. This has important implications for manufacturers and researchers, but also for regulators, which may demand country-specific minimum performance requirements for PTW active safety countermeasures.

Characteristics of early shared E-Scooter fatalities in the United States 2018–2020

This research examines the preliminary characteristics of early fatalities associated with shared e-scooters, a unique emerging mode of transportation. Using media and police reports, we identified 21 shared e-scooter fatalities which occurred in the United States from 2018 to 2020. We studied the cases and crash narratives in detail to document the characteristics present and identify potential risk factors.We found that most crashes (86%) involved motor vehicles and 28% of these were hit-and-runs. The majority of cases took place at night (81%), and adverse environmental conditions like precipitation and fog were present in 43% of cases. We suggest a framework of five possible crash configurations, and we find that two crash types represent a majority of fatalities. These two most common crash types occurred when a motor vehicle struck an e-scooter from behind, or when the e-scooter operator lost of control of the scooter.These results establish a useful point of reference for policymakers, e-scooter stakeholders, and future researchers by documenting the number and the characteristics of these fatalities. Our analysis suggests that many hazards, such as reduced visibility, poor surface conditions, and risky maneuvers, typically accumulate before a fatal e-scooter crash occurs. This may suggest multiple predictable points of conflict which could serve as places for intervention and areas of future study.

Using the Instantaneous Center of Rotation to Examine the Influence of Yaw Rate on Occupant Kinematics in Eccentric Planar Collisions

<div class="section abstract"><div class="htmlview paragraph">The biomechanical injury assessment for an occupant in a planar vehicle-to-vehicle collision often requires a kinematic analysis of impact-related occupant motion. This analysis becomes more complex when the collision force is eccentric to the center of gravity on a struck vehicle because the vehicle kinematics include both translation and potentially significant yaw rotational rates. This study examines the significance of vehicle yaw on occupant kinematics in eccentric (off-center) planar collisions. The paper describes the calculation of the instantaneous center of rotation (ICR) in a yawing vehicle post-impact and explores how mapping this quantity may inform an occupant’s trajectory when using a free particle “occupant” analysis. The study initially analyzed the impact-related occupant motion for all the outboard seat positions in a minivan using several hypothetical examples of eccentric vehicle-to-vehicle crash configurations with varying PDOF, delta-V, and yaw rate. The ICR and free particle occupant trajectories were calculated for six different simulated crash examples to illustrate which seating positions were most influenced by post-impact vehicle yaw. The process was repeated for all the outboard seat positions in a sedan using the vehicle kinematics from a staged two-vehicle crash test. It was found that the ICR can provide the crash analyst or the biomechanist a useful mechanism to visualize the relationship between vehicle and occupant kinematics in an eccentric planar vehicle collision.</div></div>

Crash Distribution Dataset: Development and Validation for the Undivided Rural Roads in Oromia, Ethiopia

Abstract Predicting the number of crashes that may occur as a result of specific highway features is critical in evaluating different treatment or design alternatives. Since different highway geometric characteristics can influence crash distribution datasets, Highway Safety Manual’s (HSM’s) predictive method encourages users to predict crashes based on their severity and collision type proportions. This study used crash data from rural two-way two-lane road segments in the Oromia region over seven years to develop Oromia’s fixed crash distribution dataset on Interactive Highway Safety Design Model (IHSDM) software. The crash distribution dataset has two parts; the crash severity proportions and the collision type percentages. The developed Oromia’s fixed crash distribution dataset was compared and validated against the default HSM crash configuration. As a result, the Crash Prediction Model (CPM) evaluation results confirmed that the developed crash severity proportion (the first part of the crash distribution dataset) estimates are more accurate and closer to the observed values. Furthermore, the findings show that crashes in the Oromia region are severer than in the states where the HSM crash configuration was developed. According to the second part of the crash distribution dataset evaluation (collision type percentage), the developed fixed crash distribution dataset outperforms the default HSM configuration in most collision type proportions, but not in all. For instance, from the ten collision type proportions developed, Right-Angle and sides-wipe collision proportions are predicted more precisely by the default HSM configuration. This points to the need for developing collision type proportion (the second part of the crash distribution dataset) as a function rather than a fixed configuration for a better result, based on the availability of complete crash data (i.e. crash location). In general, the study revealed that in order to exploit the full potential of HSM’s predictive approach, researchers must develop a jurisdiction crash distribution dataset using local crash data. The methodology demonstrated in this study to develop the jurisdiction’s crash distribution dataset has been validated as true thus, safety practitioners are encouraged to adopt it.

Estimated crash avoidance with the hypothetical introduction of automated vehicles: a simulation based on experts\u2019 assessment from French in-depth data

ObjectiveWe aimed to quantify, through simulations using real crash data, the number of potentially avoided crashes following different replacement levels of light vehicles by level-5 automated light vehicles (AVs).MethodsSince level-5 AVs are not on the road yet, or are too rare, we simulated their introduction into traffic using a national database of all fatal crashes and 5% of injury crashes observed in France in 2011. We fictitiously replaced a certain proportion of light vehicles (LVs) involved in crashes by level-5 AVs, and applied crash avoidance probabilities estimated by a number of experts regarding the capabilities of AVs depending on specific configurations. Estimates of the percentage of avoided crashes per user configuration and according to three selected (10%, 50%, 100%) replacement levels were made, as well as estimates taking into account the relative weight of these crash configurations, and considering fatal and injury crashes separately.ResultsOur simulation suggests that a reduction of almost half of fatal crashes (56%) and injury crashes (46%) could be expected by replacing all LVs on the road with level-5 AVs. The introduction of AVs would be the least effective for crashes involving a vulnerable road user, especially motorcyclists.ConclusionThis result represents encouraging prospects for the introduction of automated vehicles into traffic, while making it clear that, even with all light vehicles replaced with level 5-AVs, all issues would not be solved, especially for crashes involving motorcyclists, cyclists and pedestrians.

Injury risks and crashworthiness benefits for females and males: Which differences are physiological?

Objective Previous research has found elevated injury risk for females relative to males in passenger vehicle crashes but has not accounted for ways the crashes themselves differ between these populations. Vehicle curb weight, ride height, safety rating, airbag deployment, and crash configuration all influence injury outcome and often are not well-represented by delta-V alone. This study evaluated the effect of occupant sex on injury risk in front and side crashes while limiting or controlling for non-physiological crash differences. Additionally, the effects of crashworthiness improvements are compared for females and males. Methods NASS-CDS cases from 1998–2015 calendar years involving a belted driver in a front crash or a struck-side driver or right front passenger in a side crash were analyzed. Case vehicle model years were 1989–2016. Logistic regression was used to estimate the risk of MAIS ≥ 2 and MAIS ≥ 3 injury outcomes for females relative to males as well as the change in risk due to improved crashworthiness. Sex-based differences in occupant age, mass, and stature; crash test rating; delta-V; crash configuration; and vehicle-to-vehicle compatibility were considered either through case selection or the inclusion of additional regression covariates. Results Before controlling for crash and vehicle differences, female drivers in front crashes had higher estimated overall and body-region-specific risks of MAIS ≥ 2 and MAIS ≥ 3 injury, as consistent with previous findings. After accounting for such differences, all ratios of injury odds for females relative to males were reduced. Females remained at higher risk of MAIS ≥ 2 injury (OR, 2.23; 95% CI, 1.42–3.51), especially extremity injury, but had similar odds for MAIS ≥ 3 non-extremity injury (OR, 0.98; 95% CI, 0.56–1.7). While controlling for crash differences in side impacts, none of the estimated injury risk differences by sex were significant at the p ≤ 0.05 level. Estimated benefits of improved crashworthiness were similar or greater for females than for males for most injury outcomes. Conclusions Female-specific crashworthiness improvements may be required to provide additional protection against AIS 2 extremity injury. Much of the remaining discrepancy in sex-based injury risk can be attributed differences between vehicles and crashes, not to physiological differences. Addressing these differences will require other types of countermeasures.

Analysis of Injury Severity involving of Passenger Vehicles’ Occupants in Frontal Impact Collisions


 
 
 In Malaysia, Passenger Vehicles (PV) accounted for the second-highest proportion of vehicles involved in road crashes (13.5%) as well as the total number of casualties (18.6%) after motorcycles. This raised the alarm that a thorough investigation should be conducted on the injury severity of occupants in PV crashes involving frontal impact collisions. The objective of this study is to evaluate injury severity outcome based on the selected crash parameters for the front seat occupants involved in frontal impact collision. The data for this study was sourced from the MIROS crash investigation database (MICARS) from 2007 until 2019, during which MIROS had investigated a total of 975 cases in both East and West Malaysia. After filtering through the cases, a total of 129 frontal impact crashes (PV versus PV) involving 206 PV and 349 front seat occupants were selected for data analysis. From the total number of selected cases, 82 cases were involved in head-on collisions while 47 cases were involved in side-impact collisions. As a result, crash configuration, crush extent, airbag availability, and seatbelt wearing are strongly related to the level of injury severity of frontal seat occupants involved in a frontal impact collision. Meanwhile, collision types and occupant seating position do not appear to be significantly related to the severity of the occupants’ injuries.