Background: From the perspective of what is called "vision zero" in Sweden, fatalities and injuries among bicyclists are unacceptable. Despite that, bicyclists constitutes approximately one third of all road user inpatients in Swedish hospitals, which is about the same proportion seen for drivers and passengers of motor vehicles. There are too many bicycle-related head injuries, but the risk of such traumas could be reduced considerably by the use of helmets. Bicycle helmet wearing can be increased by voluntary means, for instance by long-term community-based helmet promotion programs. However, the best effect has been achieved by combining promotion with a compulsory helmet law for all bicyclists, as has been done in Australia, New Zealand, and North America Aim: The general aim of the research underlying this dissertation was to provide further information about the need for increased bicycle helmet use in Sweden, and to determine what measures can lead to more widespread helmet wearing. The four papers included addressed two main questions: (1) What is the need for increased helmet wearing among different categories of bicyclists in Sweden? (2) Is a non-compulsory local bicycle helmet law a realistic alternative to a mandatory helmet law for all bicyclists? Materials and methods: Observational studies of helmet use by bicyclists in Sweden were conducted once a year (average n = 37,031/year) during the period 1988-2002 (paper I). The general trend in observed helmet wearing in different categories of bicyclists was analyzed by linear regression, and the results were used to predict future trends in helmet wearing. Three studies (papers II-IV) were also performed to evaluate a non-compulsory local bicycle helmet "law" in Motala municipality during the study period 1995 to 1998 (papers II-IV). This law was introduced in 1996 and applies specifically to school children (ages 6-12 years), although the intention is to increase helmet use among all bicyclists. Adoption of the law was accompanied by helmet promotion activities. In one of the studies in the evaluation, written material and in-depth interviews (n=8) were analyzed qualitatively to describe the process and structure of development of the Motala helmet law. The other two studies used a quasi-experimental design to assess the impact of the helmet law: one comprised annual observations of helmet wearing among bicyclists in Motala (average n=2,458/year) and control areas (average n=17,818/year); and the other included questionnaire data on attitudes, beliefs, and self-reported behavior of school children in Motala (n=1,277) and control areas (n=2,198). The average response rate was 72.8%. Results and discussion: There was a significant upward trend in helmet use in all categories of bicyclists from 1988 to 2002. Helmet wearing increased from 20% to 35% among children(≤ 10 years) riding bikes in their leisure time, from 5% to 33% among school children, and from 2% to 14% in adults. Total average helmet use rose from 4% to 17%. However, during the last five years of the study period (1998-2002), there was no upward trend in helmet wearing for any of the categories of bicyclists. If the historic trend in helmet use continues, the average wearing rate will be about 30% by the year 2010. The Motala helmet law was dogged by several problems, mainly during the initiation phase, and some of them led to poor rooting of the law in the schools and indistinct roles and responsibilities of the municipal actors. Despite that, the law initially led to a significant increase in helmet wearing among the primary target group (school children), from a pre-law level of 65% to about 76% six months post-law, whereas thereafter the wearing rate gradually decreased and was at the pre-law level 2 ½ years after the law was adopted. Nonetheless, a weak but significant effect on adult bicyclists remained: the pre-law level of about 2% rose to about 8% at the end of the study period. Only about 10% of bicyclists on bike paths in Motala wore helmets 2 ½ years post-law. The questionnaire study showed one significant effect on school children in Motala two years post-law, namely, a stronger intention to ride bicycles if a national compulsory helmet law was introduced. There was, however, no significant long-term influence on children's attitudes or beliefs about helmet wearing, which agrees with the results of the observational study. General conclusions: It is indeed necessary to increase bicycle helmet wearing in Sweden. Both the current average rate of helmet use and the rate predicted for the near future are far from the goal of 80% that was officially proposed by several years ago. Previous research has shown that, to achieve substantial and sustained bicycle helmet use, it is necessary to use helmet promotion in combination with a national helmet law that is compulsory and applies to all bicyclists. The present evaluation of the non-compulsory local helmet law in Motala indicated that this type of initiative is not a powerful alternative to a mandatory national helmet law. Nevertheless, much has been learned from the initiation and implementation of this local action.

<p>The most common diagnoses after bicycle accidents are head injuries and fractures on arms and legs. At two of three injured cyclists, head injuries are the primary cause of death and bicycle helmets are a good protection against these injuries. Because the brain is very fragile, even a moderate hit can cause a serious injury. Arms and legs can often be treated, while brain damage could be a permanent disability. The main goal of this paper is to find out what makes students at Linköping University wear a bicycle helmet. The specific aim of this paper is to find out why students at Linköping University do not wear a bicycle helmet when they are cycling. The paper is divided into a literature review and a case study. The literature review delivers an insight into the road traffic safety system and the contributing factors that influence road traffic safety. It covers research analysis of experts about human behavior and gives an overview of relevant facts and figures concerning cycling within Sweden as well as within the European Union. The case study is a survey carried out at Linköping University. The method used is paper questionnaire with the target group of students at Linköping University. The result of the questionnaire is that more information regarding bicycle helmets and cycling as such, bicycle helmets for free or at least for reduced prices and to somehow change the attitudes towards bicycle helmets is important to increase the number of students wearing a bicycle helmet at Linköping University. As the most important reasons for not wearing a bicycle helmet, practical problems due to having no opportunity to fix the bicycle helmet secure to the bicycle, the fear of negative appearance and the discomfort of wearing a bicycle helmet have been mentioned. To increase the usage of bicycle helmets measures like increasing the awareness, reducing the helmet price or providing extra features with the helmet, based on the results of the literature review and the questionnaire, are suggested at the end of this paper.</p>

The most common diagnoses after bicycle accidents are head injuries and fractures on arms and legs. At two of three injured cyclists, head injuries are the primary cause of death and bicycle helmets are a good protection against these injuries. Because the brain is very fragile, even a moderate hit can cause a serious injury. Arms and legs can often be treated, while brain damage could be a permanent disability. The main goal of this paper is to find out what makes students at Linköping University wear a bicycle helmet. The specific aim of this paper is to find out why students at Linköping University do not wear a bicycle helmet when they are cycling. The paper is divided into a literature review and a case study. The literature review delivers an insight into the road traffic safety system and the contributing factors that influence road traffic safety. It covers research analysis of experts about human behavior and gives an overview of relevant facts and figures concerning cycling within Sweden as well as within the European Union. The case study is a survey carried out at Linköping University. The method used is paper questionnaire with the target group of students at Linköping University. The result of the questionnaire is that more information regarding bicycle helmets and cycling as such, bicycle helmets for free or at least for reduced prices and to somehow change the attitudes towards bicycle helmets is important to increase the number of students wearing a bicycle helmet at Linköping University. As the most important reasons for not wearing a bicycle helmet, practical problems due to having no opportunity to fix the bicycle helmet secure to the bicycle, the fear of negative appearance and the discomfort of wearing a bicycle helmet have been mentioned. To increase the usage of bicycle helmets measures like increasing the awareness, reducing the helmet price or providing extra features with the helmet, based on the results of the literature review and the questionnaire, are suggested at the end of this paper.

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Determinants of wearing a bicycle helmet were examined. Interindividual differences in helmet wearing were formalized with three different health psychological theories. The Protection Motivation Theory (PMT) [1], explains intention for a health behavior using subjective beliefs on the efficacy and costs of a specific health behavior, self-efficacy and risk and severity of negative consequences as well as benefits of not doing said behavior. The Theory of Planned Behavior (TPB) [2] uses attitude, subjective norms and behavioral control about a (health) behavior to predict intention to a behavior, which in turn can predict actual behavior. Lastly, the Health Action Process Approach (HAPA) [3] is similar to PMT, but puts more emphasis on self-efficacy while omitting costs of beneficial behavior. lt includes both intention and behavior, as well as planning as an intermediate step between intention and behavior. [From: Theory]

The aim with this master thesis was to set up a FE-simulation of an impact test of a bike helmet in LS-DYNA that correlates well with the peak acceleration score of a real life impact test. Furthermore, a parametric study has been performed in LS DYNA to investigate the robustness of the model, as well as to see which parameters have a great influence on the peak acceleration score. To investigate the acceleration of the helmet, helmet drop tests have been performed at the Borås RISE lab. Building an FE-model of the helmet drop test required multiple iterations to ensure stability and accuracy of the model. The steps of the modelling process included investigating previous simulations of helmet impacts in LS-DYNA, preprocessing of CAD, defining material models and establishing contact and boundary conditions. The parameters that have proven to have a great impact on the peak acceleration value are the tensile stress cutoff, the PC shell thickness, the strain rate dependency, and the EPS thickness. A conclusion of this work is that FE modelling is a way to approximate the peak acceleration value for linear impact tests, and a useful tool for investigating design parameters. The density of the EPS foam is shown to have a large influence on the peak acceleration value in both the experimental tests and the FE simulation. From the FE simulationns, the thickness of the EPS, as well as the thickness of the PC shell have shown to have a great impact on the peak acceleration score. / Syftet med denna masteruppsats var att sätta upp en FE-simulering av ett islagstest för en cykelhjälm i LS-DYNA som korrelerar bra med experimentella islagstest. Vidare har en parametrisk studie utförts i LS DYNA för att undersöka modellens robusthet, samt för att se vilka parametrar som har en stor påverkan på maxaccelerationen. För att undersöka hjälmens acceleration, har islagstester av cykelhjälmar utförts på RISE lab i Borås. För att bygga en FE-modell av ett islagstest krävdes flera iterationer för att säkerställa modellens stabilitet och noggrannhet. Stegen i modelleringsprocessen inkluderade undersökning av tidigare simuleringar av hjälmar i LS-DYNA, förbearbetning av CAD-filer, definiering av materialmodeller och upprättande av kontakt och gränsvillkor. De parametrar som har visat sig har en stor inverkan på det maximala accelerationsvärdet är dragspänningsgränsen, skaltjockleken på PC:n, töjningshastighetsberoendet och EPS-tjockleken. En slutsats av detta arbete är att FE-modellering är ett sätt att approximera värdet på maxaccelerationen för linjära islagstester och ett användbart verktyg för att undersöka designparametrar. Densiteten av EPS-skum har visat sig ha en stor inverkan på maxaccelerationsvärdet i både experimentella tester och FE-simuleringen.

Introduction: In January 2005, a nationwide mandatory bicycle helmet law for children under the age of 15 was introduced in Sweden. In the current study, the effect of this law was evaluated by analyzing national trends in hospital admissions due to bicycle-related head injuries during the period 1998-2011. Methods: An interrupted time-series design with segmented regression analysis was used to evaluate the intervention effect on head injuries as a percentage of all injuries (%HI) among cyclists in age- and sex-specific groups. Effect was measured as a change in level and/or slope of the trend at the time of legislation. Results: A total of 35261 cyclists (0-54 years) were hospitalized due to a bicycle injury during the study period. Linear regression analyses of the entire study period (not segmented) showed significant year-to-year decreases in the %HI of 1.3-1.7% in all age and sex-specific groups (p &lt; .0001). Results from the segmented regression analysis showed that, at the time of legislation, a significant drop in level occurred among males under 15 years (-4.5% [95% CI: -7.7% to -1.3%], p = .01) and a significant change in slope occurred among females aged 30-54 years (-1.6% [95% CI: -2.9% to -0.2%], p = .025). Conclusions: The law seems to have had an effect on males in the target population (&lt;15 years). Although no significant changes were observed among females in this group as an immediate result of the law, the difference in %HI between genders was minimal at the end of the study period due to the steeper general decline among females. / Inledning: I Sverige infördes en cykelhjälmslag för barn under 15 år den första januari 2005. Syftet med denna studie var att studera effekten av denna lag genom att analysera nationella trender i andelen huvudskador bland svenska cyklister under tidsperioden 1998-2011. Metod: Segmenterad regressionsanalys applicerades på tidsseriedata (interrupted time-series design) för att utvärdera om ett trendbrott när det gäller andelen cykelrelaterade huvudskador sammanföll med lagens införande i olika köns- och åldersspecifika grupper. Effekt mättes som en skillnad i regressionslinjens riktning och nivå. Resultat: Inom åldersgruppen 0-54 år vårdades totalt 35261 cyklister under studieperioden. Linjära regressionsanalyser (ej segmenterade) visade att mellan 1998-2011 minskade andelen huvudskador årligen minskade med 1,3–1,7 % i samtliga studerade köns- och åldersspecifika grupper. Den segmenterade regressionsanalysen visade att samtidigt som cykelhjälmslagen infördes skedde en signifikant skillnad i regressionslinjens nivå bland pojkar under 15 år (-4,5 % [95 % CI: -7,7 % till -1,3 %], p = 0,01) och en signifikant skillnad i regressionslinjens riktning bland kvinnor i åldersgruppen 30-54 år (-1,6 % [95 % CI: -2,9 % till -0,2 %], p = 0,025). Slutsats: Den svenska cykelhjälmslagen verkar ha haft en betydande inverkan på trenden i cykelrelaterade huvudskador bland pojkar under 15 år. Även om något liknande fenomen inte framstod bland flickor i interventionsgruppen bör det noteras att skillnaden i andelen huvudskador mellan könen i slutet av studieperioden var minimal.