The rate of change of acceleration: implications to head kinematics during rear-end impacts

Using contextual data to predict risky driving events: A novel methodology from explainable artificial intelligence

Usage-based insurance has allowed insurers to dynamically tailor insurance premiums by understanding when and how safe policyholders drive. However, telematics information can also be used to understand the driving contexts experienced by the driver within each trip (e.g., road types, weather, traffic). Since different combinations of these conditions affect exposure to accidents, this understanding introduces predictive opportunities in driving risk assessment. This paper investigates the relationships between driving context combinations and risk using a naturalistic driving dataset of 77,859 km. In particular, XGBoost and Random Forests are used to determine the predictive significance of driving contexts for near-misses, speeding and distraction events. Moreover, the most important contextual factors in predicting these risky events are identified and ranked through Shapley Additive Explanations. The results show that the driving context has significant power in predicting driving risk. Speed limit, weather temperature, wind speed, traffic conditions and road slope appear in the top ten most relevant features for most risky events. Analysing contextual feature variations and their influence on risky events showed that low-speed limits increase the predicted frequency of speeding and phone unlocking events, whereas high-speed limits decrease harsh accelerations. Low temperatures decrease the expected frequency of harsh manoeuvres, and precipitations increase harsh acceleration, harsh braking, and distraction events. Furthermore, road slope, intersections and pavement quality are the most critical factors among road layout attributes. The methodology presented in this study aims to support road safety stakeholders and insurers by providing insights to study the contextual risk factors that influence road accident frequency and driving risk.

On the impact of advanced driver assistance systems on driving distraction and risky behaviour: An empirical analysis of irish commercial drivers

Advanced driver assistance systems (ADAS) present promising benefits in mitigating road collisions. However, these benefits are limited when risky drivers continue engaging in distraction events. While there is evidence that real-time warnings help improve driving behaviour, the sustained benefits of warning-based ADAS on reducing driving distraction in light commercial vehicle (LCV) drivers remain unclear. This research determines the effect of receiving instant distraction warnings over two years using a naturalistic driving dataset comprising around one million trips from 373 LCV drivers in the Republic of Ireland. Furthermore, the study applies Association Rule Mining (ARM) to find the contextual variables (e.g., speed limit, road type, traffic conditions) that increase the likelihood of distraction events. The results show that warning-based ADAS providing real-time warnings helps reduce distraction events triggering driver inattention, forward collision, and lane departure warnings. Over half of the studied fleet reduced these warnings by at least 50% - lane departure after two months and driver inattention and forward collision after six months. It is found that both passive and active monitoring systems, coupled with coaching and rewards, significantly reduce aggressive driving behaviours tied to harsh acceleration (by 76%) and harsh braking (by 65%). The results of ARM show that the driving context introduces explanatory information for road safety programs. Low-speed urban roads and the summer season increase the likelihood of driver inattention and forward collision warnings. In contrast, high-speed rural roads increase the likelihood of lane departure warnings. These research findings support road safety stakeholders in developing risk assessments based on warning-based ADAS, targeted campaigns to reduce driving distraction, and driving coaching programs.

Model-Aided Design of a Rear-Impact Collision Testing System for In Vivo Investigations

A collision testing device used to simulate rear-end impacts on human volunteers was developed and validated. The testing device was designed using impact parameters obtained from real crash-test-derived vehicle-to-vehicle rear-end collisions. Experimental results show the proposed testing device achieves repeatable impact parameters well within the reported ranges of real vehicle-to-vehicle rear-end impact simulations reported in the literature. In particular, the device was able to produce a 7.66 (0.30) km/h delta-v collision with a duration of 111.6 (6.2) ms, and a 4.75 (0.29) g peak acceleration.

Does a tow-bar increase the risk of neck injury in rear-end collisions?

INTRODUCTION

Does a tow-bar increase the risk of neck injury in the struck car in a rear-end collision? The rear part of a modern car has collision zones that are rendered nonoperational when the car is equipped with a tow-bar. Past crash tests have shown that a car's acceleration was higher in a car equipped with a tow-bar and also that a dummy placed in a car with a tow-bar had higher peak acceleration in the lower neck area.

METHOD

This study aimed to investigate the association between the risk of neck injury in drivers and passengers, and the presence of a registered tow-bar on the struck car in a rear-end collision. We performed a merger of police reports, the National Hospital Discharge Registry, and the National Registry of Motor Vehicles in Denmark. We identified 9,370 drivers and passengers of whom 1,519 were diagnosed with neck injury within the first year after the collision. We found a statistically insignificant 5% decrease in the risk of neck injury in the occupants of the struck car when a tow-bar was fitted compared to when it was not fitted (hazard ratio=0.95; 95% confidence level=0.85-1.05; p=0.32). The result was controlled for gender, age, and the seat of the occupant. Several other collision and car characteristics and demographic information on the drivers and passengers were evaluated as confounders but were not statistically significant.

CONCLUSIONS

The present study may serve as valuable input for a meta-analysis on the effect of a tow-bar because negative results are necessary in order to avoid publication bias.

Anthropometrics and maturity status: A preliminary study of youth football head impact biomechanics

CONTEXT

There is a paucity of head impact biomechanics research focusing on youth athletes. Little is known about how youth subconcussive head impact tolerances are related to physical size and maturation.

OBJECTIVE

To examine the effects of age, anthropometric and maturational status variability on head impact biomechanics.

DESIGN

Cross-sectional.

SETTING

Outdoor youth football facilities in South Carolina.

PARTICIPANTS

Thirty-four male recreational youth football players, 8 to 13yrs.

INTERVENTIONS

Categorized by CDC standards, independent variables were: age, height, mass, BMI, and estimated peak height velocity (PHV). Participants wore a designated head impact sensor (xPatch) on their mastoid process during practices and games.

MAIN OUTCOME MEASURES

Linear acceleration (g) and rotational acceleration (rad/s²).

RESULTS

Boys in the older age category had a greater linear (F=17.72; P<0.001) and rotational acceleration (F=10.74; P<0.001) than those in the younger category. Post-PHV boys had higher linear (F=9.09, P=0.002) and rotational (F=5.57, P=0.018) accelerations than those who were pre-PHV. Rotational, but not linear acceleration differed by height category with lowest impacts found for the tallest category, whereas both linear and rotational accelerations by mass differences favored average and heavy categories. BMI overweight boys, had the greatest linear (F=5.25; P=0.011) and rotational acceleration (F=4.13; P=0.260) means.

CONCLUSION

Post-PHV boys who were older, taller and had longer legs, but who were not heavier, had higher impacts perhaps due to the type of impacts sustained. Taller boys' heads are above their peers possibly encouraging hits in the torso region resulting in lower impact accelerations. Obese boys did not have sequential results compared to boys in the other BMI categories probably due to league rules, player position, and lack of momentum produced.

Investigating cervical muscle response and head kinematics during right, left, frontal and rear-seated perturbations

OBJECTIVE

Whiplash research has largely focused on rear collisions because they account for the majority of whiplash injuries. The purpose of this study was to evaluate the effects of 4 perturbation directions (anterior, posterior, right, and left) on muscle activity and head kinematics to provide insight into the whiplash mechanism of injury.

METHODS

The effects of 4 perturbation directions induced by a parallel robotic platform, with peak acceleration of 8.50 m/s2, were analyzed on 10 subjects. Surface electromyography (EMG) measures were collected from the sternocleidomastoid (SCM), trapezius, and splenius capitus muscles. Kinematics of the head, thorax, and head relative to thorax were also measured.

RESULTS

We observed stereotypic responses for kinematics and SCM EMG for the various perturbation directions; the trapezius and splenius capitus muscles showed amplitudes that were less than 5 percent maximum voluntary contraction (MVC). Rear perturbations elicited the smallest onset latencies for the SCM (30 ms) and kinematic variables and greatest linear head center of mass (COM) accelerations. Frontal perturbations resulted in an average SCM onset latency of 143 ms and demonstrated the greatest magnitude of head translations and rotations relative to the thorax. Left and right perturbations demonstrated similar kinematics and SCM onset latencies (55 and 65 ms, respectively).

CONCLUSIONS

Compared to frontal, left, and right directions, rear perturbations showed smaller SCM onset latencies, greater SCM amplitudes, and larger head accelerations, relating to a greater potential for injury. We suggest that the greater contact area and stiffness of the seatback, in the posterior direction, compared to restrictions in other directions, led to increased peak head accelerations and shorter SCM onset latencies.

Head and neck control varies with perturbation acceleration but not jerk: implications for whiplash injuries

Recent studies have proposed that a high rate of acceleration onset, i.e. high jerk, during a low-speed vehicle collision increases the risk of whiplash injury by triggering inappropriate muscle responses and/or increasing peak head acceleration. Our goal was to test these proposed mechanisms at realistic jerk levels and then to determine how collision jerk affects the potential for whiplash injuries. Twenty-three seated volunteers (8 F, 15 M) were exposed to multiple experiments involving perturbations simulating the onset of a vehicle collision in eyes open and eyes closed conditions. In the first experiment, subjects experienced five forward and five rearward perturbations to look for the inappropriate muscle responses and 'floppy' head kinematics previously attributed to high jerk perturbations. In the second experiment, we independently varied the jerk ( approximately 125 to 3 000 m s(-3)) and acceleration ( approximately 0.65 to 2.6 g) of the perturbation to assess their effect on the electromyographic (EMG) responses of the sternocleidomastoid (SCM), scalene (SCAL) and cervical paraspinal (PARA) muscles and the kinematic responses of the head and neck. In the first experiment, we found neither inappropriate muscle responses nor floppy head kinematics when subjects had their eyes open, but observed two subjects with floppy head kinematics with eyes closed. In the second experiment, we found that about 70% of the variations in the SCM and SCAL responses and about 95% of the variations in head/neck kinematics were explained by changes in perturbation acceleration in both the eyes open and eyes closed conditions. Less than 2% of the variation in the muscle and kinematic responses was explained by changes in perturbation jerk and, where significant, response amplitudes diminished with increasing jerk. Based on these findings, collision jerk appears to have little or no role in the genesis of whiplash injuries in low-speed vehicle crashes.