Garrett Mattos

Cervical and thoracic spine injury from interactions with vehicle roofs in pure rollover crashes

Around one third of serious injuries sustained by belted, non-ejected occupants in pure rollover crashes occur to the spine. Dynamic rollover crash test methodologies have been established in Australia and the United States, with the aims of understanding injury potential in rollovers and establishing the basis of an occupant rollover protection crashworthiness test protocol that could be adopted by consumer new car assessment programmes and government regulators internationally. However, for any proposed test protocol to be effective in reducing the high trauma burden resulting from rollover crashes, appropriate anthropomorphic devices that replicate real-world injury mechanisms and biomechanical loads are required. To date, consensus regarding the combination of anthropomorphic device and neck injury criteria for rollover crash tests has not been reached. The aim of the present study is to provide new information pertaining to the nature and mechanisms of spine injury in pure rollover crashes, and to assist in the assessment of spine injury potential in rollover crash tests. Real-world spine injury cases that resulted from pure rollover crashes in the United States between 2000 and 2009 are identified, and compared with cadaver experiments under vertical load by other authors. The analysis is restricted to contained, restrained occupants that were injured from contact with the vehicle roof structure during a pure rollover, and the role of roof intrusion in creating potential for spine injury is assessed. Recommendations for assessing the potential for spine injury in rollover occupant protection crash test protocols are made.

Head Injuries to Restrained Occupants in Single-Vehicle Pure Rollover Crashes

Objective: Studies performed previously of seat-belted occupants in real-world passenger vehicle rollover-only crashes have identified the head as one of the body regions most often seriously injured. However, there have been few studies investigating how these head injuries occur in any detail. This study aims to investigate the characteristics and patterns of head injury to seat-belted occupants in real-world rollover-only crashes and to identify possible biomechanical mechanisms responsible for head injury to aid in the development of a dynamic rollover test protocol. Methods: National Automotive Sampling System–Crashworthiness Data System (NASS-CDS) data were used to generate summary statistics and perform logistic regression analysis of restrained and contained occupants in U.S. pure trip-over rollover crashes. Specific information from selected CDS cases focused on identifying potential mechanisms and patterns of serious head injury and the rollover conditions under which the injury occurred are also presented. Results: Twenty-one percent of seriously injured occupants in pure trip-over rollovers had a serious head injury. On average, occupants seated on the far side of the rollover sustained serious head injuries more frequently and were more likely to receive injuries to the inboard side of the head than near-side occupants. Serious head injuries appear to be decoupled from serious injuries to other body regions except for a relationship found between basal skull fractures and cervical spine fractures. Serious head injuries were sustained by some occupants who had less than 15 cm of roof crush above their seated position. Conclusions: Serious brain injuries appear to occur frequently as a result of loading to the periphery of the head from contact with the roof assembly. Two mechanisms of injury for basal skull fractures in rollover crashes were identified. The injury patterns and locations of contact to the head are sensitive to the seated position of the occupant.

Validation of a dynamic rollover test device

The Jordan Rollover System (JRS) is a device designed, with minimal constraints, to simulate a dynamic trip-over rollover crash. It has been shown to perform with a high degree of repeatability in regards to test protocol inputs and vehicle performance outputs and is the test device of choice for three separate research facilities around the world. The performance of a selection of vehicles, as tested on the JRS at the Center for Injury Research, was compared via logistic regression to their real world injury rate in single-vehicle rollovers using police-reported crash data. Results indicate that vehicles which experienced more roof crush in a JRS test generally experienced higher rates of incapacitating and fatal injury in real world rollover crashes.

Comparison of novice and full-licenced driver common crash types in New South Wales, Australia, 2001–2011

OBJECTIVE To examine the circumstances of passenger vehicle crashes for novice licenced drivers aged 17-25 years and to compare the crash circumstances of the most common crash types for novices to a sample of full-licence drivers aged 40-49 years. METHOD A retrospective analysis was conducted of passenger vehicle crashes involving novice and full-licenced drivers during 1 January 2001 to 31 December 2011 in New South Wales (NSW), Australia. RESULTS There were 4113 injurious crashes of novice drivers. Almost half the novice driver crashes involved a single vehicle. Vehicle speed (33.2%), fatigue (15.6%) and alcohol (12.6%) were identified risk factors in novice driver crashes. Correspondence analysis for 4 common crash types for novice drivers revealed that the crash characteristics between novice and full-licenced drivers were similar. CONCLUSIONS Similarities exist between novice driver and full-licenced driver crash risk for common crash types. Preventive strategies aimed at crash risk reduction for novice drivers may also benefit all drivers.

Roof Damage Patterns and Serious Head Injuries in Pure Rollover Crashes

This study evaluated the association between the pattern of roof damage resulting from a pure rollover crash and the incidence of serious head injuries (SHIs) for contained, restrained occupants. As part of a larger project with the goal of developing a dynamic crash test protocol for rollover occupant protection, these associations will help to define the initial conditions of a rollover test that produce the damage patterns that are most likely to result in SHI. Pure rollover crashes from the U.S. National Automotive Sampling Systems Crashworthiness Data System were used in the study. The roof damage pattern above the seat position of each occupant in the data set was identified by the photographs included in each case file and coded to one of eight specified patterns; 1,151 cases in which the damage pattern could be determined for a relevant rollover occupant were identified. SHIs were observed only for cases with evidence of a roof-to-ground impact. Although the results indicated that this pattern of roof damage was associated with the occurrence of SHI, the pattern was rarely more significant than other crash outcome parameters.

Computer modelling of vehicle rollover crash tests conducted with the UNSW Jordan Rollover System

ABSTRACT Vehicle rollovers are one of the least forgiving crash modes with one of the highest occupant fatality and serious-injury rates. A detailed understanding of the mechanisms associated to injuries resulting from vehicle rollovers is essential for the development of effective occupant-protection countermeasures during a rollover. Crash testing devices such as the Jordan Rollover System (JRS) recently have been used for investigating vehicle rollovers within a testing environment. Computer simulations of such rollover crash tests would provide a valuable support by allowing to greatly reduce the number of tests otherwise necessary for identifying the most critical test conditions as well as conducting comprehensive parametric studies. This paper describes a modelling effort to simulate vehicle rollover crash testing conducted with the University of New South Wales (UNSW) JRS, which is an improved version of the original JRS. A detailed finite element (FE) model of the UNSW JRS was coupled with FE models of both a small passenger car and a sport utility vehicle. Relevant physical phenomena that have to be modelled for successfully simulating such complex testing were initially identified. Both modelled configurations were validated against experimental rollover tests performed with the corresponding vehicle and proved to be capable of replicating the actual vehicle dynamics and deformations. Such developed FE model will be a useful tool for detailed investigations of vehicle rollover crash tests conducted with the UNSW JRS.

Sensitivity of head and cervical spine injury measures to impact factors relevant to rollover crashes.

Objective: Serious head and cervical spine injuries have been shown to occur mostly independent of one another in pure rollover crashes. In an attempt to define a dynamic rollover crash test protocol that can replicate serious injuries to the head and cervical spine, it is important to understand the conditions that are likely to produce serious injuries to these 2 body regions. The objective of this research is to analyze the effect that impact factors relevant to a rollover crash have on the injury metrics of the head and cervical spine, with a specific interest in the differentiation between independent injuries and those that are predicted to occur concomitantly. Methods: A series of head impacts was simulated using a detailed finite element model of the human body, the Total HUman Model for Safety (THUMS), in which the impactor velocity, displacement, and direction were varied. The performance of the model was assessed against available experimental tests performed under comparable conditions. Indirect, kinematic-based, and direct, tissue-level, injury metrics were used to assess the likelihood of serious injuries to the head and cervical spine. Results: The performance of the THUMS head and spine in reconstructed experimental impacts compared well to reported values. All impact factors were significantly associated with injury measures for both the head and cervical spine. Increases in impact velocity and displacement resulted in increases in nearly all injury measures, whereas impactor orientation had opposite effects on brain and cervical spine injury metrics. The greatest cervical spine injury measures were recorded in an impact with a 15° anterior orientation. The greatest brain injury measures occurred when the impactor was at its maximum (45°) angle. Conclusions: The overall kinetic and kinematic response of the THUMS head and cervical spine in reconstructed experiment conditions compare well with reported values, although the occurrence of fractures was overpredicted. The trends in predicted head and cervical spine injury measures were analyzed for 90 simulated impact conditions. Impactor orientation was the only factor that could potentially explain the isolated nature of serious head and spine injuries under rollover crash conditions. The opposing trends of injury measures for the brain and cervical spine indicate that it is unlikely to reproduce the injuries simultaneously in a dynamic rollover test.

Head and Spine Injuries Sustained by Motorcyclists in Head-Leading Collisions with Fixed Roadside Objects

Objective: Motorcyclist collisions with fixed objects account for a substantial proportion of fatalities in many countries. Biomechanically valid crash test protocols are required to assess the injury potential of different fixed objects to motorcyclists and/or to develop safety devices that ameliorate this injury risk. The aim of the present article is to provide field-observed injury data pertaining to motorcyclist head-leading collisions with fixed objects to assist in the development of crash test protocols. Method: The Australian National Coronial Information System was used to identify fatal motorcyclist head-leading collisions with fixed objects. Head and spine injuries were identified from the autopsy reports for these individuals. The head impact locations and injuries were used to infer impact orientations and corresponding injury mechanisms. Results: A sample of 44 motorcyclists estimated to have impacted fixed objects in the head-leading orientation was identified. The analysis of autopsy reports indicated a predominance of basilar skull fractures, intracranial injuries to the frontal cerebrum and inferior aspects of the brain (brainstem and cerebellum), and upper cervical spine injuries. Analysis of head impact locations identified a predominance of impacts to the frontal and/or lateral aspects and when considered in combination with the injury mechanisms, a typical impact orientation of sliding in the prone position with head extension was inferred. Conclusions: The study results were used to suggest possible crash test protocols for motorcyclists sliding into fixed objects and/or safety devices designed to reduce the injury risk of fixed objects. The predominant orientation of lying prone with head extension led the authors to suggest a crash test using the motorcycle anthropomorphic test device (MATD) sliding prone. However, the occurrence of the supine orientation, albeit less frequent, indicates the utility of a crash test with an anthropomorphic test device (ATD) sliding supine. The 2 options are discussed, particularly with regard to appropriate injury assessment reference values.

250 Pedestrian-vehicle interactions: early results from the Australian naturalistic driving study (ands)

Background Typologies have been defined previously for pedestrian-vehicle interactions and are primarily based on retrospective analysis of crash data. The naturalistic driving study currently underway in Australia makes it possible to study pedestrian-vehicle interaction events that would not otherwise be identified in the crash data. This work evaluates the feasibility of using automated, manual, and semi-automated methods to identify pedestrian-vehicle interaction events. Methods Sensors and cameras were installed on the vehicles of volunteers in and around two major Australian cities which recorded their natural driving behaviour for 4 months. Forward video from select vehicles was reviewed independently by two reviewers to identify potential pedestrian-vehicle interaction events from which a typology of behaviours was formulated. These events served as the gold standard against which select automated and semi-automated methods of identification were assessed. Results A prototype typology of pedestrian-vehicle interaction events was formulated using naturalistic driving data and categorised in terms of risk of being struck. Some case scenarios will be discussed. The feasibility of using select automated, semi-automated, and manual methods to identify these events was also evaluated. Conclusions This work provides a first look at using Australian naturalistic driving data to study the interactions between vehicles and pedestrians. These findings will assist in the development of methods that can be used to most effectively answer research questions pertaining to interactions between vehicles and pedestrians as well as other vulnerable road users in the future.

Mean Injury Costs of Run-Off-Road Collisions with Fixed Objects: Passenger Vehicles and Motorcycles

Cost–benefit analyses are an important analytical tool for road authorities to assess and prioritize road safety countermeasures, and commit funds that maximize road safety benefits. The aim of this study is to establish field-observed crash, injury, and cost data for run-off-road collisions with various fixed hazards and roadside infrastructure, and to derive accurate and reliable cost values for such objects for use in run-off-road cost–benefit analyses. Values are derived for passenger vehicle occupants and motorcyclists. Accurate cost data is vital to ensure cost–benefit analyses are rigorous and reliable. Data linkage between police-reported road crash, hospitalization, and personal injury insurance claim data collections is used to identify fixed-object collisions, the injuries sustained, and to establish the associated costs of treatment. A total of 5,004 passenger vehicle and 1,364 motorcycle casualties resulting from fixed-object collisions are identified, and mean injury costs per collision are established for various types of objects. The new cost values may be used in conjunction with existing cost–benefit procedures, to accurately cost fixed-object collisions and assist road authorities with decisions relating to roadside design and the commitment of funds for road safety countermeasures.