Bicycle helmet use four years after the introduction of helmet legislation in Alberta, Canada

Background

Bicycle helmets reduce fatal and non-fatal head and face injuries. This study evaluated the effect of mandatory bicycle helmet legislation targeted at those less than 18 years old on helmet use for all ages in Alberta.

Methods

Two comparable studies were conducted two years before and four years after the introduction of helmet legislation in Alberta in 2002. Bicyclists were observed in randomly selected sites in Calgary and Edmonton and eight smaller communities from June to October. Helmet wearing and rider characteristics were recorded by trained observers. Poisson regression adjusting for clustering by site was used to obtain helmet prevalence (HP) and prevalence ratio (PR) (2006 vs. 2000) estimates.

Results

There were 4002 bicyclists observed in 2000 and 5365 in 2006. Overall, HP changed from 75% to 92% among children, 30% to 63% among adolescents and 52% to 55% among adults. Controlling for city, location, companionship, neighborhood age proportion <18, socioeconomic status, and weather conditions, helmet use increased 29% among children (PR = 1.29; 95% CI: 1.20–1.39), over 2-fold among adolescents (PR 2.12; 95% CI: 1.75–2.56), and 14% among adults: (PR = 1.14; CI: 1.02–1.27).

Conclusions

Bicycle helmet legislation was associated with a greater increase in helmet use among the target age group (<18). Though HP increased over 2-fold among adolescents to an estimated 63% in 2006, this percentage was approximately 30% lower than among children <13.     

Bicycle safety helmet legislation and bicycle-related non-fatal injuries in California

The objective of this study was to determine whether the bicycle safety helmet legislation in California, enacted in 1994, was associated with statistically significant reductions in head injuries among bicyclists aged 17 years and under who were subjected to the law. The study used 44,069 patient discharge cases from all public hospitals in California, from 1991 through 2000, and a case-control design to make direct comparisons between those subjected to the law (Youth) and those who were not (Adult) across the pre- and post-legislation periods. An aggregate data analysis approach and a pooled disaggregate data fitting technique using multinomial logit models were applied. The legislation was found to be associated with a reduction of 18.2% (99% confidence interval: 11.5-24.3%) in the proportion of traumatic brain injuries (Head-TBI) among Youth bicyclists. The proportions of other head, face, and neck injuries were not significantly changed across the pre- and post-legislation periods in this age group but there was a corresponding increase of 9% (5-13%) in the proportion of all other injuries. On the other hand, there was no statistically significant change in the proportions of injury outcomes for Adult bicyclists. The youngest riders, aged 0-9 years, had the greatest decrease in the proportion of Head-TBI. The reduction was the same for motor vehicle and non-motor-vehicle-related incidents. The bicycle safety helmet legislation was associated with a decrease in the likelihood of Head-TBI for non-urban residents but not for urbanites, for males but not for females, and for Whites, Asians, and Hispanics, but not Blacks and others.     

Publication bias and time-trend bias in meta-analysis of bicycle helmet efficacy: a re-analysis of Attewell, Glase and McFadden, 2001

This paper shows that the meta-analysis of bicycle helmet efficacy reported by Attewell, Glase, and McFadden (Accident Analysis and Prevention 2001, 345–352) was influenced by publication bias and time-trend bias that was not controlled for. As a result, the analysis reported inflated estimates of the effects of bicycle helmets. This paper presents a re-analysis of the study. The re-analysis included: (1) detecting and adjusting for publication bias by means of the trim-and-fill method; (2) ensuring the inclusion of all published studies by means of continuity corrections of estimates of effect rely on zero counts; (3) detecting and trying to account for a time-trend bias in estimates of the effects of bicycle helmets; (4) updating the study by including recently published studies evaluating the effects of bicycle helmets. The re-analysis shows smaller safety benefits associated with the use of bicycle helmets than the original study.     

Bicycle helmets: lack of efficacy against brain injury

This paper is a rebuttal of the criticism by Hagel and Pless of my 2005 article in which I dispute the conclusion of a Cochrane Collaboration review that all types of standard bicycle helmet protect against injury to the brain. The main ground of rebuttal is that my critics take the relevant efficacy of helmets as given and argue from there.     

Bicycle injuries: a matter of mechanism and age

Bicycle riding is a popular form of recreation with positive health and environmental effects. These road users are vulnerable to serious injuries, especially when motor vehicles are involved. The goal of this study was to characterize cyclist-related injuries according to motor vehicle involvement for adults versus children. A retrospective study was carried out using data from 11 trauma centers in the Israeli National Trauma Registry (2001-2007). Injuries were classified according to whether a motor vehicle was involved, and differences in injury characteristics were assessed for adults (18+ years) versus children (1-17 years). A total of 5529 patients were hospitalized for bicycle injuries, of whom 1765 were adults and 3764 were children. Thirty percent (n=1662) of all bicycle injuries involved motor vehicles, although the rate of injuries resulting in hospitalization was 37% among adults and 27% among children. Injury characteristics and hospital resource utilization differed substantially by age group. Cyclists struck by a motor vehicle presented with more severe injuries requiring more hospital resources and resulting in poorer outcomes than those not involved with motor vehicles. The interaction effect between motor vehicle involvement and age was significant for torso injuries and need for medical imaging. We found that injury characteristics, hospital resource utilization and health-related outcomes for bicycle injuries are highly dependent on patient's age and mechanism of injury. Effect modification of motor vehicle involvement by age may in part reflect physicians' attitudes toward pediatric imaging. The risks identified in this study should be used for preparedness and management of trauma hospitalizations from bicycle injuries.     

Ballistic impact of a KEVLAR helmet: Experiment and simulations

This paper presents the results from experiments and AUTODYN-3D^® simulations on the ballistic impact of a KEVLAR^® helmet. In the experiment, spherical projectile (∼11.9 g), launched from a light gas gun, strikes the helmet with an impact velocity of 205 m/s. The interaction of the projectile with the KEVLAR^® helmet is captured using high-speed photography. This helmet-projectile interaction is compared with that obtained from the AUTODYN-3D^® simulation. Post-test damage photos from the experiments are also compared with those from the simulations. The response of the helmet from the simulations is consistent with those from the experiments. Also included in this paper are AUTODYN-3D^® simulations on two ballistics test standards for KEVLAR^® helmets. They are namely the NIJ-STD-0106.01 Type II and the V₅₀ requirement of the US military specification for Personal Armor System Ground Troops (PASGT) Helmet, MIL-H-44099A. For the simulation on MIL-H-44099A, a fragment-simulating projectile (FSP) strikes the helmet with an impact velocity of 610 m/s. The simulation revealed that an impact velocity above 610 m/s is required to perforate the KEVLAR^® helmet. For the simulation on NIJ-STD-0106.01 Type II helmet, the projectile is a 9 mm full-jacketed bullet with a striking velocity of 358 m/s. Results from the simulation show that the KEVLAR^® helmet is able to defeat a 9 mm full-jacketed bullet traveling at 358 m/s.     

Bicycle injuries in Western Sweden: a comparison between counties

The objectives of the study were to investigate whether there are differences in the incidence of bicycle-related injuries by geographic district (county), age, and gender in Sweden's Western Road Administration Region, and to utilize any detected differences to suggest priorities for intervention and prevention. Injury data come from the Swedish national hospital-discharge registry and a specialized national register of occupational injuries. Both bodily injuries in general and head injuries in particular show intra-regional differences. The rural part of Skaraborg County was shown to have a significantly higher injury incidence than other parts of the Western Region. Females generally show a lower incidence than males, but older women are more likely to be seriously injured than younger (age-related differences being greater than for males). Some striking findings were found with regard to occupational differences. Females sustain more work-related bicycle injuries than males. Head injuries account for more than half of the bicycle injuries in the Western Region that require hospitalization. All this indicates that targeted measures are required. Some studies have shown that the use of bicycle helmets reduces the incidence of head injuries, the degree of their severity, and the number of bicycle-related fatalities. There is a need for mandatory helmet-wearing legislation, which must go hand-in-hand with special efforts to reach groups with a low rate of helmet wearing, in particular those in the middle age range. Although the grown-up/older cycling population has been the subject of targeted action in some countries, the focus of preventive activity has generally been on children. The results of the study suggest the need for further injury-related research into adult cycling.     

FEA of oblique impact tests on a motorcycle helmet

In accidents, motorcycle riders full-face helmets often make oblique impacts with road surfaces. Finite element analysis was used to predict the rotational and linear acceleration of a Hybrid II headform, representing a motorcyclist's head, in such impacts, considering the effects of friction at the head/helmet and helmet/road interfaces. Simulations of the oblique impact test in British Standard BS 6658 were validated by comparison with published data. This showed that COST 327 experimental data was largely determined by the friction coefficient (0.55) between the helmet shell and abrasive paper, and hardly affected by that between the head and helmet. Slip was predicted at the shell/paper interface throughout the impact, due to the high angular inertia of the helmet, and the normal force remaining below 3.5 kN. Simulations of more severe motorcycle helmet impacts explored the effects of impact site and direction, impact velocity components, helmet fit and the scalp. In these impacts, the higher velocity component normal to the road caused high frictional forces on the helmet shell, eventually causing it to roll on the road. The peak headform rotational accelerations, at some impact sites, were potentially injurious. The most effective method of reducing head rotational acceleration could be a reduction in the linear acceleration limit of the helmet standards.     

Trends in helmet use and head injuries in San Diego County: the effect of bicycle helmet legislation

The purpose of this study is to evaluate the effect of California's bicycle helmet law on bicycle-related head injuries in San Diego County with a year 2000 population of approximately 3 million people. The study design is an ecological trend design based on observational data from a Trauma Registry. Outcome measures include helmet use compliance, site/severity of injury and abbreviated injury scale (AIS). There were 1116 bicycle trauma patients recorded in the San Diego County Trauma Registry between 1992 and 1996. The percentages of pre-law and post-law helmet use were 13.2 and 31.7%, respectively. Over the whole study period, the overall helmet use increased by an average of 43% per year with an averaged 84% rate increase in helmet use among children. Only 16.1% of patients with serious head injury used helmets, compared to 28.2% in those who did not have serious head injury. The odds ratio of helmet use against serious head injuries is 0.43 (95% CI 0.28-0.66) after adjusting for age, ethnicity and time. The p-values for comparing pre- and post-legislation serious head injury rates are p=0.764, 0.4 and 0.194 for the overall, adult and child populations, respectively. Helmet legislation increased helmet use in the targeted child population and the effect was carried over to the adult population. Helmet use has a protective effect against serious head injury. Probably due to several of its limitations, the current study did not confirm that helmet legislation alone significantly reduced head injury rates in San Diego County during the study period.     

Bicycle crash casualties in a highly motorized city

The characteristics of bicycle crashes in cities where bicycles are a minor transport mode have received little attention in road safety research. However, the characteristics of these injury-inflicting bicycle crashes are expected to be very different from those happening in cities where cycling is generally considered as one of the major transport modes. Specifically, this study has the following three objectives: (1) to conduct the first scientific spatial analysis of bicycle crashes in Hong Kong; (2) to analyze the circumstances leading to bicycle crashes; and (3) to conduct an epidemiological study on injury patterns of cyclist casualties. Various spatial and statistical tools, including buffer analysis, chi-square tests, analysis-of-variance and binary logistic regression, are used to analyze the bicycle crashes in Hong Kong from 2005-2007. An important finding of this paper is that the bicycle safety problem has a clear spatial dimension. The crash circumstances in different parts of the city differed systematically. Furthermore, the findings suggest that initiatives to develop new cycle tracks and to encourage bicycles as a transport mode must be planned carefully with new infrastructure and policies to ensure the safety of cyclists.     

Bicycle accidents and injuries: a pilot study comparing hospital- and police-reported data

Bicycle accident and injury data collected by two different samples of North Carolina hospital emergency rooms during the summers of 1985 and 1986 are examined and compared with state police-reported bicycle accident data for the same time periods. Of the 649 emergency room treated bicyclists, 62% were children aged 5-14 and 70% were male. Nineteen percent of the riders suffered moderate or worse injuries (AIS greater than or equal to 2), and 6% were hospitalized. In contrast, less than half of the police-reported accidents involved riders under 15 years of age, 85% of the riders were male, and two-thirds suffered moderate or worse injury. Whereas virtually all of the police-reported accidents involved a motor vehicle, less than a fifth of the emergency room cases did. Only 10% of the emergency room cases were duplicated on the state accident files. It is estimated that 800 children ages 0-19 are hospitalized annually in North Carolina for bicycle-related injuries, and an additional 13,300 children receive emergency room treatment.     

电动自行车及其电池

电动自行车作为一种新型的交通工具,越来越受到人们的欢迎.综述了电动自行车及其电池的现状和前景,指出了电动自行车发展过程中存在的一些问题,并提出了一些个人看法.     

Motorcycle riders' perception of helmet use: complaints and dissatisfaction

In accidents which involve two-wheeled vehicles the helmet plays a life-saving role, but very little is known about the motorcycle rider's perception of the helmet. We evaluated the relationships between having been involved in an accident and dissatisfaction with the helmet, and between the perception of motorcycle riders and the objective features of the helmet. This was a case-control study: riders of motorized two-wheelers who had been involved in accidents (accident cases) were compared against a similarly interviewed sample of riders that had not been in accidents (control cases). Information about the driver, the vehicle and the helmet was collected in all interviews. To evaluate the relationships, logistic regressions were carried out. The majority of drivers were dissatisfied with their helmets, but no evidence was found to link this dissatisfaction with having been involved in an accident. The two most common complaints related to noisiness, followed by the helmet visor. Complaints did not seem to be statistically associated with physical features of the helmet.     

Shock absorption performance of a motorbike helmet with honeycomb reinforced liner

The enhancement of the energy absorption properties of motorbike helmets could significantly improve the safety of riders. This study reports a novel concept of helmet design, which consists in the use of aluminium honeycomb as reinforcement material of the helmet liner. A modified version of a commercial helmet is presented, in which aluminium honeycombs are used in the energy absorbing liner. The ECE 22.05 standard tests were performed on both the prototype helmets and their commercial counterparts (presenting same dimensions, geometry, material properties and weight), and the dynamic responses were compared. The results showed that the prototype helmets provided better protection to the head from impacts against the kerbstone anvil. More limited improvements were also observed in some of the impacts on flat anvil, although other results indicated to some extent the limitations of the strategy adopted in our research.     

Improper motorcycle helmet use in provincial areas of a developing country

Motorcycle helmet wearing rates remain low in smaller cities in developing countries. We therefore examined the knowledge, attitudes, and behavior of motorcyclists towards helmet use in two mid-sized cities in China. The methods included roadside observation and interview. Observational sites were randomly selected from main roads and secondary streets; all motorcycles passing by were observed. Riders near the sites were opportunistically approached and asked about knowledge of and perceptions about helmet use. Altogether, 75,949 drivers and 17,230 passengers were observed. A large proportion of both drivers and passengers (34% and 71%, respectively) did not wear a helmet, or did not have their helmet fastened (34% and 14%). Proper helmet usage rates were lower among male drivers, younger people, on secondary streets, and during the evenings and weekends. The majority of the 2325 drivers interviewed (90%) acknowledged the benefits of helmet wearing, but 72% reported that helmets are not always comfortable, and only 20% said they would wear a helmet for preventive purposes. Furthermore, many felt that police enforcement was not strict (62%). These results suggest that educational programs about helmet use in provincial China should emphasize the risks of improper use. Strict enforcement, especially on secondary roads and during non-peak hours, could also improve helmet usage.     

Cycle helmet effectiveness in New Zealand

Since late 1989, the cycle helmet wearing rate in New Zealand has risen from around 20% for adults and teenagers, and 40% for younger children, to more than 90% in all age groups. Cycle helmet wearing became mandatory under New Zealand law in January 1994. This paper considers the effect of cycle helmet wearing on hospitalised head injuries between 1990 and 1996, using cyclist limb injuries as a measure of exposure to the risk of cycling trauma. Non-motor vehicle crashes were treated separately from those involving a motor vehicle. Non-motor vehicle crashes were further subdivided by age group. Cyclist head injuries decreased with increasing helmet wearing rates for non-motor vehicle crashes in all age groups, and for motor vehicle crashes. For an increase of 5 percentage points in the helmet wearing rate, the corresponding decreases in head injuries in non-motor vehicle accidents were estimated to be 10.2, 5.3 and 3.2% for children of primary school age (5–12 years), secondary school age (13–18 years), and adults respectively. The corresponding decrease in hospitalisations for motor vehicle crashes was 3.6%. All results were significant at the 95% level. The relatively large increase in helmet wearing associated with the passing of a compulsory helmet wearing law in 1994 reduced head injuries by between 24 and 32% in non-motor vehicle crashes, and by 20% in motor vehicle crashes. No increase or decrease in the severity of head injuries for which cyclists were hospitalised over this period could be detected. This may have been due to the small and highly variable number of ‘high severity’ injuries.     

Emotional reactions to cycle helmet use

It has been suggested that the safety benefits of bicycle helmets are limited by risk compensation. The current article tests if previous helmet use influences the response to helmets as a safety intervention. This was investigated in a field experiment where pace and psychophysiological load were measured. We found that after having removed their helmets, routine helmet users cycled more slowly and demonstrated increased psychophysiological load. However, for non-users there was no significant change in either cycling behaviour or psychophysiological load. We discuss the implications of these results for a hypothesis of risk compensation in response to helmet use. We also show that heart rate variability is a promising measure of psychophysiological load in real-world cycling, at least in situations where there is limited physical demand.     

Bicycle helmets and brain injury

This paper replies to criticism by Cummings et al. [Cummings, P., Rivara, F.P., Thompson, D.C., Thompson, R.S., 2006. Accid. Anal. Prev. 38, 636-643] of an article [Curnow, W.J., 2005. The Cochrane Collaboration and bicycle helmets. Accid. Anal. Prev. 37, 569-573] disputing a conclusion of a Cochrane Collaboration review, namely, that it establishes scientific evidence that all types of standard bicycle helmet protect against injury to the brain. In response to the conclusion of Cummings that the review's case-control studies provide such evidence, I explain that their design is inadequate to do this.     

Characteristics of motorcycle-related hospitalizations: comparing states with different helmet laws

This study compares U.S. motorcycle-related hospitalizations across states with differing helmet laws. Cross-sectional analyses of hospital discharge data from 33 states participating in the Healthcare Cost and Utilization Project in 2001 were conducted. Results revealed that motorcyclists hospitalized from states without universal helmet laws are more likely to die during the hospitalization, sustain severe traumatic brain injury, be discharged to long-term care facilities, and lack private health insurance. This study further illustrates and substantiates the increased burden of hospitalization and long-term care seen in states that lack universal motorcycle helmet use laws.