| 1. |
- Annaheim, Simon, et al.
(author)
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Final report of Working Group 4: Ergonomics of thermal effects. A COST Action TU1101 / HOPE collaboration
- 2015
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Reports (other academic/artistic)abstract
- The thermal effects related to wearing a bicycle helmet are complex and different studies have investigated single parts of this topic. A literature review was produced and published (Bogerd et al., 2015) summarizing the different findings to give a complete overview on this topic as well as to suggest new perspectives. Headgear increases head insulation and therefore is mainly problematic under warm conditions, which is the focus of that review. Helmets do not affect physiological parameters other than the local skin temperature and sweat rate. However, the head is among the most sensitive body parts related to thermal comfort, thereby directly affecting the willingness to wear headgear. Several methods have been used to study thermal aspects of headgear, which could be categorized as (i) numerical, (ii) biophysical, (iii) combined numerical and biophysical, and (iv) user trials. The application of these methods established that heat transfer mainly takes place through radiation and convection. Headgear parameters relevant to these heat transfer pathways are reviewed and suggestions are provided for improving existing headgear concepts and developing new concepts, ultimately leading to more accepted headgear. The report of working group 4 (WG4) provides information about activities undertaken during the COST Action TU1101 “Towards safer bicycling through optimization of bicycle helmets and usage” to better understand the ergonomics of thermal aspects and to work towards the tasks defined in the memorandum of understanding (COST Secretariat, 2011). Primary Task 5: Development of guidelines for thermally-optimized helmet designs Secondary Task 3: Inform impact studies on which kinds of ventilation structures are useful and which are unnecessary Secondary Task 7: Review of physiological and comfort effect of wearing bicycle helmets All the chapters listed below include important aspects contributing to the primary task 5. Modelling and simulation tools (Chapter II) are becoming more and more important in research and development of new bicycle helmets but also in the development of guidelines, directives and norms. An example for the industrial application of models is given in Chapter III. The investigation of different forms of helmet coverings provides important information about the future direction for the development of helmet designs. Completely new helmet designs and the respective thermal properties are presented in Chapter IV. This chapter shows a different approach for finding new concepts of helmet designs. In Chapter V, new project initiatives are introduced to improve thermal aspects of helmets but also to include information and communication techniques (ICT) into helmets. Finally, the tasks of WG4 are summarized in Chapter VI, conclusions are drawn and an outlook is provided regarding the future development of helmets to comply with the requests of two-wheel commuters (including e-bikes, segway and others).
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| 2. |
- Bogerd, Cornelis P., et al.
(author)
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A review on ergonomics of headgear: Thermal effects
- 2015
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In: International Journal of Industrial Ergonomics. - : Elsevier BV. - 0169-8141. ; 45:February, s. 1-12
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Research review (peer-reviewed)abstract
- The thermal effects related to wearing headgear are complex and different studies have investigated single parts of this topic. This review aims at summarizing the different findings to give a complete overview on this topic as well as to suggest new perspectives. Headgear increases head insulation and therefore is mainly problematic under warm conditions, which is the focus of this review. Helmets do not affect physiological parameters other than the local skin temperature and sweat rate. However, the head is among the most sensitive body parts related to thermal comfort, thereby directly affecting the willingness to wear headgear. Several methods have been used to study thermal aspects of headgear, which could be categorized as (i) numerical, (ii) biophysical, (iii) combined numerical and biophysical, and (iv) user trials. The application of these methods established that heat transfer mainly takes place through radiation and convection. Headgear parameters relevant to these heat transfer pathways, are reviewed and suggestions are provided for improving existing headgear concepts and developing new concepts, ultimately leading to more accepted headgear. Relevance to industry: This review provides a sound basis for improving existing headgear concepts. Firstly, a concise overview of headgear research related to thermal effects is given, leading to empirically based improvement suggestions and identification of research fields with a high potential. Finally, relevant research methods are described facilitating evaluation in R&D processes.
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| 3. |
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| 4. |
- Bröde, Peter, et al.
(author)
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Assessment of Thermal Discomfort when Wearing Bicycle Helmets – A Modelling Framework
- 2015
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In: International Cycling Safety Conference 2015.
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Conference paper (peer-reviewed)abstract
- Excessive sweating is a major ergonomic concern in bicycle helmet use and low wearing rates are suspected to originate, at least partly, from impaired thermal comfort due to accumulated sweat increasing skin wettedness at the head region. As a development from COST Action TU1101 WG4, we introduce a modelling framework for assessing the thermal comfort of bicy-cle helmet use. We predicted local sweat rate (LSR) at the head region as ratio to gross sweat rate (GSR) of the whole body and also based on sudomotor sensitivity (SUD), which relates the change in LSR to the change in body core temperature (ΔTre). We coupled those local models with models of thermoregulation predicting ΔTre and GSR, thus modelling head sweating in re-sponse to the characteristics of the thermal environment, clothing, level of activity, and expo-sure duration. We then validated the predictions of several local models (SUD, LSR/GSR) com-bined with different whole-body models against head sweat rates measured in the laboratory. Eventually, we developed thermal comfort criteria from head LSR by relating skin wettedness to the thermal properties of bicycle helmets. We discuss the potential of this approach as well as needs for further research.
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| 5. |
- Mukunthan, Shriram, et al.
(author)
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A comparison between physical and virtual experiments of convective heat transfer between head and bicycle helmet
- 2017
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In: Advances in Human Factors in Simulation and Modeling - Proceedings of the AHFE 2017 International Conference on Human Factors in Simulation and Modeling, 2017. - Cham : Springer International Publishing. - 2194-5357. - 9783319605906 ; 591, s. 517-527
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Conference paper (peer-reviewed)abstract
- Thermal performance of five bicycle helmets was evaluated with a thermal manikin head with six zones. Evaluation was made with physical and virtual experimental methods. Ambient temperature maintained at 24 °C and surface temperature of the thermal manikin head was set to 34 °C. Experiments were performed for air velocities of 1.6 m/s and 6 m/s. Heat transfer (W) of four thermal zones was recorded for five helmets and compared with a nude thermal manikin head to assess thermal performance. Virtual experiments were performed using commercial CFD codes with a realizable k-e turbulence model. Correlation coefficients of 0.78 (1.6 m/s) and 0.79 (6 m/s) were found between physical and virtual experiments. A combined physical and virtual evaluation methodology allows creating a design iteration process with virtual prototypes, physical prototypes and commercially available helmets.
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| 6. |
- Mukunthan, Shriram, et al.
(author)
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Thermal-performance evaluation of bicycle helmets for convective and evaporative heat loss at low and moderate cycling speeds
- 2019
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In: Applied Sciences (Switzerland). - : MDPI AG. - 2076-3417. ; 9:18
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Journal article (peer-reviewed)abstract
- The main objective of the study was to investigate the thermal performance of five (open and closed) bicycle helmets for convective and evaporative heat transfer using a nine-zone thermal manikin. The shape of the thermal manikin was obtained by averaging the 3D-point coordinates of the head over a sample of 85 head scans of human subjects, obtained through magnetic resonance imaging (MRI) and 3D-printed. Experiments were carried out in two stages, (i) a convective test and (ii) an evaporative test, with ambient temperature maintained at 20.5 ± 0.5 °C and manikin skin temperature at 30.5 - 0.5 °C for both the tests. Results showed that the evaporative heat transfer contributed up to 51%-53% of the total heat loss from the nude head. For the convective tests, the open helmet A1 having the highest number of vents among tested helmets showed the highest cooling efficiency at 3 m/s (100.9%) and at 6 m/s (101.6%) and the closed helmet (A2) with fewer inlets and outlets and limited internal channels showed the lowest cooling efficiency at 3 m/s (75.6%) and at 6 m/s (84.4%). For the evaporative tests, the open helmet A1 showed the highest cooling efficiency at 3 m/s (97.8%), the open helmet A4 showed the highest cooling efficiency at 6 m/s (96.7%) and the closed helmet A2 showed the lowest cooling efficiency at 3 m/s (79.8%) and at 6 m/s (89.9%). Two-way analysis of variance (ANOVA) showed that the zonal heat-flux values for the two tested velocities were significantly different (p < 0.05) for both the modes of heat transfer. For the convective tests, at 3 m/s, the frontal zone (256-283 W/m2) recorded the highest heat flux for open helmets, the facial zone (210-212 W/m2) recorded the highest heat flux for closed helmets and the parietal zone (54-123W/m2) recorded the lowest heat flux values for all helmets. At 6 m/s, the frontal zone (233-310 W/m2) recorded the highest heat flux for open helmets and the closed helmet H1, the facial zone (266W/m2) recorded the highest heat flux for the closed helmet A2 and the parietal zone (65-123 W/m2) recorded the lowest heat flux for all the helmets. For evaporative tests, at 3 m/s, the frontal zone (547-615W/m2) recorded the highest heat flux for all open helmets and the closed helmet H1, the facial zone (469W/m2) recorded the highest heat flux for the closed helmet A2 and the parietal zone (61-204 W/m2) recorded the lowest heat flux for all helmets. At 6 m/s, the frontal zone (564-621W/m2) recorded highest heat flux for all the helmets and the parietal zone (97-260W/m2) recorded the lowest heat flux for all helmets.
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| 7. |
- Shinar, David, et al.
(author)
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Reporting bicycle accidents to police in the COST TU1101 survey data base: Cross-country comparisons and associated factors
- 2016
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In: ; , s. 9-9
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Conference paper (peer-reviewed)abstract
- Police crash reports are often the main source for official data in many countries. However, police sampling and data are known to be subject to bias, making the countermeasures adopted according to them possibly inefficient. In the case of bicycle crashes, this bias is most acute and it probably varies across countries, with some of them being more prone to reporting accidents to police than others. Assessing if this bias occurs and the size of it can be of great importance for evaluating the risks associated with bicycling. The following paper utilizes data collected in the COST TU1101 action. The data came from an online survey that included questions related with bicyclists' attitudes, accidents, and pattern of use of helmets. An average of only 10% of all crashes were reported to the police (minimum of 0.0% Israel and 3.37% Greece to a maximum of a 30% of Germany). Some factors associated with the reporting level were: type of crash, type of vehicle and injury severity. Finally, no relation was found between the likelihood of reporting and the cyclist's gender, age, use of helmet, and type of bicycle. The significant under-reporting justifies the use of survey data for assessment of bicycling crash patterns as they relate to crash risk issues such as location, cyclists' characteristics, and use of helmet and strategic approaches to bicycle crash prevention and injury reduction, which are discussed in the paper.
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| 8. |
- Shinar, David, et al.
(author)
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Under-reporting bicycle accidents to police in the COST TU1101 international survey: Cross-country comparisons and associated factors
- 2018
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In: Accident Analysis and Prevention. - : Elsevier BV. - 0001-4575. ; 110, s. 177-186
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Journal article (peer-reviewed)abstract
- Police crash reports are often the main source for official data in many countries. However, with the exception of fatal crashes, crashes are often underreported in a biased manner. Consequently, the countermeasures adopted according to them may be inefficient. In the case of bicycle crashes, this bias is most acute and it probably varies across countries, with some of them being more prone to reporting accidents to police than others. Assessing if this bias occurs and the size of it can be of great importance for evaluating the risks associated with bicycling.This study utilized data collected in the COST TU1101 action “Towards safer bicycling through optimization of bicycle helmets and usage”. The data came from an online survey that included questions related to bicyclists' attitudes, behaviour, cycling habits, accidents, and patterns of use of helmets. The survey was filled by 8655 bicyclists from 30 different countries. After applying various exclusion factors, 7015 questionnaires filled by adult cyclists from 17 countries, each with at least 100 valid responses, remained in our sample.The results showed that across all countries, an average of only 10% of all crashes were reported to the police, with a wide range among countries: from a minimum of 0.0% (Israel) and 2.6% (Croatia) to a maximum of a 35.0% (Germany). Some factors associated with the reporting levels were type of crash, type of vehicle involved, and injury severity. No relation was found between the likelihood of reporting and the cyclist's gender, age, educational level, marital status, being a parent, use of helmet, and type of bicycle.The significant under-reporting – including injury crashes that do not lead to hospitalization – justifies the use of self-report survey data for assessment of bicycling crash patterns as they relate to (1) crash risk issues such as location, infrastructure, cyclists' characteristics, and use of helmet and (2) strategic approaches to bicycle crash prevention and injury reduction.
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