Murray Mackay

Seat Belt Use Under Voluntary and Mandatory Conditions and its Effect on Casualties

Seat belt usage rates in Britain in the decade prior to the introduction of a mandatory usage law in January 1983 are reviewed to show a stable rate of around 30% in the 1970s. Various risk compensation theories are mentioned briefly, and then some observational data collected in 1982 are analysed to show that certain vehicle characteristics, notably car age and type, have a significant relationship with occupant belt usage rates under voluntary conditions. Speed and belt usage rates do not appear to be related. The audience effect of passenger presence on belt usage rates is discussed.

MULTIVARIATE ANALYSIS OF MOTORCYCLE ACCIDENTS AND THE EFFECTS OF EXCLUSIVE MOTORCYCLE LANES IN MALAYSIA

This paper presents a multivariate analysis on the impact of the exclusive motorcycle lane on motorcycle accidents along the Federal Highway Route 2, Malaysia. A number of statistical models have been developed to explain the relationship of motorcycle accidents and explanatory variables relevant to motorcycle safety. The best model showed that motorcycle accidents are directly proportional to the cubic power of traffic flow and reduced by approximately 39% with the motorcycle lane. A clear benefit of this lane is observed when the traffic flow exceeds 15,000 vehicles per day per lane for motorcycle proportion of between 20% and 30%. Besides supporting the notion for motorcycle segregation, this finding provides an initial guideline on the warrants for an exclusive motorcycle lane for highly motorcycled countries in Asia.

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.

BOOSTER SEATS FOR CHILDREN: CLOSING THE GAP BETWEEN SCIENCE AND PUBLIC POLICY IN THE UNITED STATES

The Association for the Advancement of Automotive Medicine (AAAM) sponsored an international conference, April 23-24, 2001, in Washington, D.C., to promote scientifically sound public policy on child booster seats in motor vehicles. This commentary lists 12 recommendations drafted by the conference planning committee, and also includes a brief summary of relevant scientific evidence presented at the conference related to each recommendation.

Global priorities for vehicle safety

Presently, just over 1 million people die annually in road crashes; that number will rise to 2 million by 2020. 85% of these fatal crashes occur in developing countries, and of those, about 75% involve pedestrians, bicyclists, and motorcyclists. Over the past 10 years several organizations have attempted to outline the nature and severity of these traffic injuries and predict trends for the next decade. This commentary selectively touches on issues in traffic safety, related to global efforts to reduce traffic injuries and fatalities, within the context of the next 20 years.

A Review of the Biomechanics of Impacts in Road Accidents

The real world characteristics of road accidents relevant to biomechanical considerations will be outlined. A brief introduction to the Abbreviated Injury Scale will be given, and then the frequencies and severities of the major collision types will be presented in terms of velocity change for various injury levels. Crash severity distributions for restrained and unrestrained conditions will be analysed. Distributions of injuries by anatomical regions will be illustrated for car occupants in the main types of collisions; frontal, lateral, rear and rollover. The limits of protection of current restraint systems will be illustrated. Gender, age, height, weight and sitting positions will be analysed to show the wide biomechanical response of the actual population exposed in collisions. The consequences of these real world variations for the optimisation of seat belts, using intelligent restraint system technology, will be presented.

Injuries in Collisions Involving Small Cars in Europe

Some of the characteristics of traffic accidents involving small cars in Europe are reviewed. A classification procedure is suggested whereby crashes may be categorized by their equivalent test in the laboratory. A sample of accidents is used to illustrate this procedure and the collision characteristics. The limited relevance of the distributed frontal barrier test to real world accidents is shown. Examples of particular features which produce injury are illustrated by cases. Three-point belts are discussed, and some injuries associated with poor positioning are illustrated. Small car steering assembly design is mentioned because field experience suggests that actual function of the steering assemblies in crashes is still not optimal. Problems of seat deformation and mounting failures in relation to injury patterns are discussed briefly, and the crash performance of glass reinforced plastics is mentioned.

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.

Two Years’ Experience with the Seat Belt Law in Britain

Seat belt use rates are discussed and some vehicle, user and environmental factors influencing voluntary usage rates are outlined. Educational efforts in raising usage rates in Britain voluntarily, showed a ceiling level of 30 to 40%. The legislative process leading up to the passage of the seat belt law in Britain is described and the main issues of public policy are outlined. The provisions of the law introduced in January 1983 are summarised, and then its effect on belt usage rates, deaths and casualties is reviewed. A 25% reduction in deaths and injuries on a year-on-year basis occurred coincident with an increase in belt use from about 40% to 90%. No significant changes appear to have occurred in other casualty classes. Some of the practical problems which have appeared post-law are discussed. Finally, some longer term casualty rate data are presented to illustrate the role of the seat belt legislation in trends over the last decade. The continuing problems of restrained drivers being injured from steering wheels is mentioned, together with the effects of no rear seat belts being required in cars in Britain.

THE STRUCTURE OF EUROPEAN RESEARCH INTO THE BIOMECHANICS OF IMPACTS

This paper reviews briefly some of the trends in biomechanical research in Europe. Current terminology is discussed and a set of definitions is proposed for the common descriptors of injury, injury severity and performance criteria based on the responses observed in the living human body, in cadavers and in other surrogates. Some of the more obvious gaps in current biomechanical knowledge are discussed, particularly the need to examine the consequences of trauma at the cellular level, and some problems of experimental design in relation to research as the basis for legislation in Europe are outlined. For the covering abstract of the conference see HS-036 716. (Author/TRRL)