Correlation of head injury to vehicle contact points using crash injury research and engineering network data

Improving roadside design policies for safety enhancement using hazard-based duration modeling

Roadway departure (RwD) crashes, comprising run-off-road (ROR) and cross-median/centerline head-on collisions, are one of the most lethal crash types. Nationwide, from 2014 to 2016, annual RwD crashes accounted for 53% of all motor vehicle traffic fatalities. Several factors may cause a driver leave the travel lane, including an avoidance maneuver and inattention or fatigue. Roadway and roadside geometric design features (e.g., lane widths and clear zones) play a significant role in whether human error results in a crash. In this paper, we present a hazard-based duration model to investigate the distance traveled by an errant vehicle in a run-off-road crash, the stopping hazard rates, and associated risk factors. For this study, we obtained five years' (2010-2014) of crash data related to roadway departures (i.e., overturn and fixed-object crashes) from the Federal Highway Administration's Highway Safety Information System Database. The results indicate that over 50% of the observed vehicles traveled no more than 36 ft. in a ROR crash and 25% of the observed vehicles traveled at least 78 ft. We also found that seasonal, roadway, and crash variables, along with vehicle information and driver characteristics significantly contributed to the distances traveled by errant vehicles in ROR crashes. This paper presents methodological empirical evidence that the Cox proportional-hazards model is appropriate for investigating the distances traveled by errant vehicles in ROR crashes. In addition, it also provides valuable information for traffic design and management agencies to improve roadside design policies and implementing appropriately forgiving roadsides for errant vehicles.

Investigating occupant safety through simulating the interaction between side curtain airbag deployment and an out-of-position occupant

The objective of this research is to elucidate the effect of side curtain airbag deployment on occupant injuries and safety when the occupant is either in-position or out-of-position (OOP). We used side impact vehicle collision simulations with a 1996 Dodge Neon model, which was further modified to include a side curtain airbag, a seatbelt, and a 50th percentile Hybrid III dummy. The airbag used in the study was inflated using both the uniform pressure (UP) and smooth particle hydrodynamics (SPH) methods. In-position and OOP simulations were performed to assess and establish guidelines for airbag aggressivity thresholds and occupant position versus risk of injury. Three different OOP scenarios (OOP1, OOP2, OOP3) were initially setup following the work of Lund (2003), then modified such that the dummy's head was closer to the airbag, increasing the chance of injury caused by the airbag. The resultant head acceleration as a function of time for in-position and OOP simulations shows that both UP and SPH methods produce similar peak accelerations in cases where the airbag is fully inflated prior to impact. In all cases, the head peak accelerations and the head injury criteria for simulations with an airbag were significantly lower when compared with the no airbag case, which would typically indicate that the use of an airbag results in improved occupant protection during side impact. However, in the case of OOP2 and OOP3, the neck flexion forces actually increase significantly when compared with the no airbag case. This finding indicates that the HIC and neck flexion forces criterion are in conflict and that there may be a tradeoff in terms of occupant injury/safety with a side curtain airbag that is strongly correlated to the occupant position. Consequently, this study shows that safety devices result in a significant effect on occupant injury/safety when the occupant is in OOP conditions. Moreover, in some cases, simulation results show that the side curtain airbag may not make the occupant safer. This study requires further investigation of the vehicle-specific airbag and its interaction with an occupant in various OOP conditions.

Head impact contact points for restrained child occupants

OBJECTIVE

Head injuries are the most common injuries sustained by children in motor vehicle crashes regardless of age, restraint, and crash direction. For rear seat occupants, the interaction of the subject with the seat back and the vehicle side interior structures has been previously highlighted. In order to advance this knowledge to the development of countermeasures, a summary of vehicle components that contributed to these injuries is needed. Therefore, the objective of this study was to create a contact map of the vehicle interior for head and face injuries to rear-seated restrained children in front crashes.

METHODS

The Crash Injury Research and Engineering Network (CIREN) was queried for rear-seated, restrained child occupants (age 0-15 years) in forward-facing child restraints, booster seats, or lap and shoulder belts who sustained an AIS2+ head and/or face injury in a frontal motor vehicle crash. Cases were analyzed to describe injury patterns and injury causation scenarios. A contact point map was developed to summarize the vehicle components related to injury causation of the head/face injury.

RESULTS

Twenty-one cases met the combined inclusion and exclusion criteria. Seven of the child occupants were restrained in forward-facing child restraints, 2 in belt-positioning booster seats, and 12 in lap and shoulder belts. There were 28 head and 17 facial injuries. For left rear occupants, the most common contact point was the pillar in front of the occupant's seat row; that is, B-pillar for second-row occupants, indicating a leftward kinematics. For right rear occupants, due to differences in crash dynamics, the most common contact point location was the passenger's seat back, suggesting that these occupants moved predominantly forward.

CONCLUSIONS

Contact points associated with head/face injury for restrained children 0 to 15 years in frontal crashes have been delineated. In a majority of the cases, the head/face injury was the most severe injury and severe injuries to other body regions were uncommon, suggesting that efforts to mitigate head injuries for these occupants would greatly improve their overall safety. The majority of the head/face contact points were to the first row seat back and B-pillar. In these frontal crashes, the importance of head/face contact with the vehicle side structure suggests that deploying a curtain air bag in frontal impacts may help manage the energy of impact. These data advance the current understanding of injury patterns and causation in frontal crashes involving restrained rear-row occupants and can be used to develop solutions to mitigate the injuries sustained.

Identification of vehicle components associated with severe thoracic injury in motor vehicle crashes: a CIREN and NASS analysis

INTRODUCTION

Thoracic trauma secondary to motor vehicle crashes (MVC) continues to be a major cause of morbidity and mortality. Specific vehicle features may increase the risk of severe thoracic injury when striking the occupant. We sought to determine which vehicle contact points were associated with an increased risk of severe thoracic injury in MVC to focus subsequent design modifications necessary to reduce thoracic injury.

METHODS

The National Automotive Sampling System (NASS) databases from 1993 to 2001 and the Crash Injury Research and Engineering Network (CIREN) databases from 1996 to 2004 were analyzed separately using univariate and multivariate logistic regression stratified by restraint use and crash direction. The risk of driver thoracic injury, defined as an abbreviated injury scale (AIS) of score > or =3, was determined as it related to specific points of contact between the vehicle and the driver.

RESULTS

The incidence of severe chest injury in NASS and CIREN were 5.5% and 33%, respectively. The steering wheel, door panel, armrest, and seat were identified as contact points associated with an increased risk of severe chest injury. The door panel and arm rest were consistently a frequent cause of severe injury in both the NASS and CIREN data.

CONCLUSIONS

Several vehicle contact points, including the steering wheel, door panel, armrest and seat are associated with an increased risk of severe thoracic injury when striking the occupant. These elements need to be further investigated to determine which characteristics need to be manipulated in order to reduce thoracic trauma during a crash.

Long-term cognitive, emotional, and functional outcomes in trauma intensive care unit survivors without intracranial hemorrhage

BACKGROUND

Trauma patients without intracranial hemorrhage or focal neurologic deficits are typically considered low risk for lasting neuropsychological and emotional deficits, and such sequela may be overlooked, especially in those with skull fractures and concussions. We undertook this study to determine the prevalence of and risk factors for persistent cognitive impairment and emotional and functional difficulties in a sample of adult trauma intensive care unit survivors without intracranial hemorrhage.

METHODS

We queried the Vanderbilt University Trauma Registry for all patients admitted during 2003 with an Injury Severity Score >25 and a head computed tomography scan showing no intracranial hemorrhage. Of the 97 patients identified, 58 were evaluated, in person between 12 to 24 months after hospital discharge, with a comprehensive battery of cognitive, emotional, and functional instruments. The Informant Questionnaire of Cognitive Decline in the Elderly-Short Form (IQCODE-SF) was used to evaluate for pre-existing cognitive deficits in patients suspected of having cognitive impairment before their trauma.

RESULTS

A total of 33 (57%) patients were determined to have cognitive impairment, which was most pronounced in the domains of attention and executive functioning/verbal fluency. Of these patients, one (3%) was determined by the IQCODE-SF to be cognitively impaired before trauma intensive care unit hospitalization. Of the 58 patients studied, 21 (36.2%) had a concussion or skull fracture and 37 (63.8%) had neither. Cognitive impairment was significantly more likely to occur in patients who sustained a concussion or skull fracture than in trauma patients who did not (81% versus 43%; p = 0.006). Patients reported significant depressive symptoms (56%), significant symptoms of posttraumatic stress disorder (38%), and significant symptoms of anxiety (29%). Quality of life scores were lower than in the general United States population and employment difficulties were widespread. A total of 34% of patients reported being unemployed at follow-up, and cognitive impairment was more common among these patients compared with patients in the workforce (p = 0.03). Neither cognitive impairment nor emotional dysfunction was associated with age, sex, race, Injury Severity Score, blood loss, ventilatory days, or intramedullary nailing of long-bone fractures.

CONCLUSIONS

The majority of trauma survivors without intracranial hemorrhage display persistent cognitive impairment, which is nearly twice as likely in those with skull fractures or concussions. This cognitive impairment was associated with functional defects, poor quality of life, and an inability to return to work. Future research must delineate modifiable risk factors for these poor outcomes, especially in patients with skull fractures and concussions, to help improve long-term cognitive and functional status.

Traumatic Brain Injury and Automotive Design: Making Motor Vehicles Safer

BACKGROUND

Traumatic brain injury (TBI) remains a major public health problem in the United States. Identifying and modifying vehicle designs associated with TBI will have a significant impact on the frequency and severity of TBI in motor vehicle crashes (MVCs). Our objective, therefore, was to identify interior vehicle contact points associated with severe TBI (head Abbreviated Injury Scale score > 3) among drivers and determine the extent to which modifications of these contact points impact the likelihood of severe TBI.

METHODS

We analyzed drivers in MVCs from the 1993 to 2001 National Automotive Sampling System database. The odds of severe TBI with respect to various vehicle contact points were estimated using multivariate logistic regression. Using computer simulation software, the magnitude of driver head deceleration was modeled while manipulating vehicle design features. The potential impact of this design modification on the frequency and hospital charges of TBI cases was estimated.

RESULTS

There were 18,313 drivers involved who were victims of TBI, equating to a national sample size of 3,275,472 cases. The most frequent contact point associated with severe TBI was the roof rail (odds ratio, 2.0; 95% confidence interval, 1.2-3.3). Increasing roof rail padding thickness to 5.0 cm reduced the peak acceleration from 700 g to 218 g, which would potentially reduce the attributable number of severe TBI cases per year from 2,730 to 210, thereby reducing annual acute care charges from $136.5 million to $10.5 million US dollars.

CONCLUSION

Contact with the roof rail significantly increases the likelihood of TBI in MVCs. Minor increases in padding at these points may reduce the frequency of severe TBI, which would have a substantial effect on health care costs.