Julian Hill

Chest and abdominal injuries caused by seat belt loading

Injuries will inevitably occur when restraining loads are exerted on a car occupant by a seat belt during a crash. This study investigated the nature, frequency, and severity of such injuries to the chest and abdomen. Vehicle, occupant, and injury details were obtained from accidents occurring in the Midlands of England. The sample was chosen with emphasis on fatal and serious injuries while also representing slight injuries as rated by the British government scheme. All causes of injuries to 3,276 front-seat restrained occupants were considered. 29.6% had a minor (Abbreviated Injury Scale [AIS] 1) injury caused by seat belt loading, more than from any other cause. The study went on to focus on 1,025 occupants sustaining injuries caused solely by seat belt loading. Of those, 19.4% sustained chest/abdominal injuries rated at Maximum AIS > or = 2 with sternum fractures predominating, and 4.5% were rated at Maximum AIS > or = 3. Occupants were not excluded if they had injuries at other body regions enabling the frequency and severity of head injuries to be considered also. The role played by impact type, speed change at impact, seat belt usage problems, and some aspects of occupant characteristics were investigated. While females were at much greater risk of serious injury (AIS > or = 3) when aged > or = 70 years, the effects of aging were more obvious in the cases with chest injuries rated at AIS 2. Serious chest injuries were predominantly a function of higher speed changes at impact. Occupant height and weight were shown to influence injury outcome, and the study concluded that work is required to further define occupants most at risk. Comparisons were made with two studies into other types of injury at other body regions, and injuries rated AIS > or = 2 caused by seat belt loading were seen to be relatively unlikely. It must also be stressed that casualties sustained seat belt injuries would most likely have received more severe injuries had a seat belt not been worn.

HEAD INJURIES IN LATERAL IMPACT COLLISIONS

Individual non-minor injuries (Abbreviated Injury Scale (AIS) > or = 2) to the head that occurred to belted and unbelted drivers and front seat passengers on the stuck side of impacted vehicles were examined. Injury type, injury combination, collision severity in relation to type of injury as well as contact sources were assessed. Forty-eight percent of injuries were moderate in severity (AIS 2). The most common type of injury was the diffuse brain injury, typically marked by a short period of unconsciousness, which occurred in collisions of lower severity than focal brain and skull fracture injuries. One-hundred and five out of 216 (48.6%) of contact sources for all injury types originated from outside the vehicle and such exterior sources were more likely to result in high severity injuries. Thirty percent of injuries resulted from head contacts with other vehicles. The most frequent vehicle interior contact source was the side window glass. Diffuse injuries tended to occur independently of other injury types and were more likely to originate from an interior rather than exterior contact. Preventative measures for head injury reduction in lateral collisions are discussed. Overall, the data show that proposed and present European and U.S. lateral impact test methods do not address many head injury problems such as those included in this study.

Restrained occupants on the nonstruck side in lateral collisions

Of injury-producing collisions with high seat belt use, some 25% to 30% are lateral collisions. This paper describes some of the characteristics of those collisions as they relate to the front-seat occupant sitting on the side opposite to the impact. The data came from a stratified sample of in-depth crash investigations conducted in the Birmingham region in the period 1983 to 1989 involving current model cars. Crash severity was assessed using the Vehicle Deformation Index (VDI) of the Collision Deformation Classification (CDC) ratings and velocity change. Injury severity was assessed using AIS 85 for each body region. 193 cases of restrained occupants in nonstruck side collisions were examined. Of those occupants with head injuries of AIS < or = 2, 35% came out of the shoulder section of the seat belt. Of abdominal injuries of AIS < or = 2, 72% came from the seat belt itself. Interaction between front seat occupants was not a frequent cause of injury to the nonstruck side occupant. Some aspects of seat belt geometry might be changed so that the trajectory and loading of the nonstruck side occupant are improved.

Maxillofacial injuries following steering wheel contact by drivers using seat belts

Maxillofacial injuries are common sequelae in road traffic accidents. For the restrained driver, impact against the steering wheel is the most prevalent cause of injury. A sample of drivers restrained by seat belts with facial injury caused by the steering wheel was taken from data at the Accident Research Unit, University of Birmingham, UK. Two hundred and forty facial injuries occurred in 135 drivers, and these are described. Superficial contusion, laceration and nasal fractures predominated. There were 504 injuries at other body regions, and these were often caused by other vehicle components. These were, for 57% of drivers, no more serious than the facial injury caused by steering wheel contact. The role of steering wheel design in maxillofacial trauma is discussed and new solutions briefly reviewed.

Single-Vehicle Collisions in Europe: Analysis Using Real-World and Crash-Test Data

Many European road casualties result from vehicles leaving the road, often impacting roadside obstacles. As part of the European Commission-funded project RISER (Roadside Infrastructure for Safer European Roads), several activities were undertaken to collate the type of real world crash data which is needed to understand single vehicle crash situations and relate this to crash-test data mandated in the European Union. Accident data were collected and used to create databases exclusively for single-vehicle collisions on major rural roads, simulation software was used to further understand impacts with roadside structures, and an inventory of crash-test data was collected for impacts with poles and safety barriers. The combination of accident data, simulations and crash-test data has provided a unique insight into the characteristics of single-vehicle collisions, helping those involved in the design and evaluation of the roadside environment to understand them better and make recommendations for consideration when drafting design guidelines.

LEG INJURY RISK IN FRONTAL COLLISIONS

This paper describes lower limb injuries which might be assessed for current or proposed barrier tests for belted drivers in frontal impacts. Injury and impairment were rated using the Abbreviated Injury Scale (AIS) and the Injury Impairment Scale (IIS). Both emphasised the importance of fracture, especially to the ankle/foot region. AIS equal to or greater than 2 and IIS equal to or greater than 1 injury rates were high with small driver side (right side) overlaps. However, a high rate was also found for wide overlap impacts with driver side load concentration. Passenger shell intrusion was frequently associated with injuries of AIS equal to or greater than 2 and ISS equal to or greater than 1. Injuries of this type occasionally occurred with low intrusion and at low impact speeds. The injuries will be important in view of the frequency of those types of crashes in the tow-away population. Femur and ankle/foot fractures were sustained predominantly by the right limb. It is recommended that further experimental work is carried out. The aim is to determine the specific injury mechanisms involved with different intrusion levels at given impact speeds. (A) For the covering abstract of the conference see IRRD 875833.

Appropriate frontal barrier tests for belted occupants

Vehicle damage from frontal impacts was classified and investigated together with injuries sustained by belted front seat occupants. The sample consisted of 1872 frontal crashes from the Midlands of England. Analysis focused on impacts with broad objects that might conceivably be simulated by a barrier test. Two asymmetrical front-end damage patterns were commonly identified, and these gave the greatest rates of non-minor (Abbreviated Injury Scale (AIS) > or = 2) injuries in a range of Estimated Test Speeds from 35 to 52km/h which is the regime of current legislative crash tests. The most injurious type involved oblique damage caused by a substantial overlap of the struck object. The other type was from a small overlap. Objects struck and passenger compartment intrusions were compared. Appropriate asymmetrical and deformable barrier concepts were discussed. Other findings were connected with the future role of full face barriers as used in current tests such as Federal Motor Vehicle Safety Standard 208. Fuller overlaps (> 50%) tended to give more torso injuries rated > or = AIS 2 caused by seat belt loads and, at high speeds (53-79km/h), caused the most fatalities. Full overlaps (100%) rarely resulted in symmetrical intrusion into the passenger compartment.

Reset to Zero and Specify Active Safety Systems according to Real-World Needs

Emergency brake assist, adaptive cruise control, and alternative instantiations of intelligent vehicle control systems aspire to support the driver in controlling the vehicle and alleviate the incidents that would lead to collisions and injury. This paper resets to zero and based on data from the on-the-spot accident study challenges the capability of active safety systems to aim at the sources of longitudinal control failures. The road user interactions file from 3,024 road accidents in Thames Valley and Nottinghamshire in U.K. was analyzed. Interactions where “failure to stop” or “sudden braking” is the precipitating factor are analyzed and the main contributory factors are identified. Some of those factors are addressed by current and coming technologies—such as low road friction, excessive speed, and close following, but other common ones are significantly neglected—such as distraction, failure to judge other person’s path, failure to look, and “look, but did not see” instances.

Use of Car Crashes Resulting in Fatal and Serious Injuries to Analyze a Safe Road Transport System Model and to Identify System Weaknesses

Objective: The objective of this study was to evaluate a model for a safe road transport system, based on some safety performance indicators regarding the road user, the vehicle, and the road, by using crashes with fatally and seriously injured car occupants. The study also aimed to evaluate whether the model could be used to identify system weaknesses and components (road user, vehicles, and road) where improvements would yield the highest potential for further reductions in serious injuries. Methods: Real-life car crashes with serious injury outcomes (Maximum Abbreviated Injury Scale 2+) were classified according to the vehicles safety rating by Euro NCAP (European New Car Assessment Programme) and whether the vehicle was fitted with ESC (Electronic Stability Control). For each crash, the road was also classified according to EuroRAP (European Road Assessment Programme) criteria, and human behavior in terms of speeding, seat belt use, and driving under the influence of alcohol/drugs. Each crash was compared and classified according to the model criteria. Crashes where the safety criteria were not met in more than one of the 3 components were reclassified to identify whether all the components were correlated to the injury outcome. In-depth crash injury data collected by the UK On The Spot (OTS) accident investigation project was used in this study. All crashes in the OTS database occurring between 2000 and 2005 with a car occupant with injury rated MAIS2+ were included, for a total of 101 crashes with 120 occupants. Results: It was possible to classify 90 percent of the crashes according to the model. Eighty-six percent of the occupants were injured when more than one of the 3 components were noncompliant with the safety criteria. These cases were reclassified to identify whether all of the components were correlated to the injury outcome. In 39 of the total 108 cases, at least two components were still seen to interact. The remaining cases were only related to one of the safety criteria, namely, the road user (26), the vehicle (19), and the road (24). The criteria for the road and the vehicle did not address multiple event crashes, rear-end crashes, hitting stationary/parked vehicles, or trailers. Conclusions: The model for a safe road transport system was found useful to classify fatal and serious road vehicle crashes. It was possible to classify 90 percent of the crashes according to the safety road transport model. For all these cases it was possible to identify weaknesses and parts of the road transport system with the highest potential to prevent fatal and serious injuries. Injury outcomes were mostly related to an interaction between the 3 components: the road, the vehicle, and the road user.

SEAT BELT LIMITATIONS IN COLLISIONS THAT INVOLVE NO COMPROMISE OF THE PASSENGER COMPARTMENT

This is a field study of cars that sustained very little passenger compartment intrusion in frontal crashes. It has been possible to define the key limits on seat belt effectiveness in these, the most common type of crash. Data are taken from the in-depth investigations by the Co-operative Crash Injury Study and Rover Group in the UK. Vehicle crashworthiness is assessed in detail and then matched with medical information from coroners reports, hospital records or questionnaires sent to survivors. The study describes and compares important injury mechanisms such as driver head to steering wheel contacts, front passenger torso injuries caused by seat belt loads and front occupant leg injuries. 14% of occupants were rated two or above on the Maximum Abbreviated Injury Scale. It is realistic to design seat belt systems for use in passenger compartments that can be expected not to deform in the more common frontal crashes. The discussion is concerned with the importance of these results when developing safety systems in that context. (A) For the covering abstract see IRRD 893297.