Motorcycle Helmet Standards – Harmonisation and Specialisation?
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MOTORCYCLE HELMET STANDARDS – HARMONISATION AND SPECIALISATION? Andrew McIntosh Transport and Road Safety (TARS) Research, University of New South Wales Australia McIntosh Consultancy and Research Australia. Raphael Grzebieta Transport and Road Safety (TARS) Research, University of New South Wales Australia Paper number 13-0160 ABSTRACT There are a number of major motorcycle helmet Motorcycle helmets have been shown to reduce the standards, e.g. AS/NZS 1698, DOT, JIS T 8133, risk of death by 42% and head injury by 69%. Snell M2010 and UN/ECE 22. With international Mild traumatic brain injury appears to be the trade agreements, on-line purchasing, and prevalent form of injury suffered by helmeted motorcycling growth there is a need to assess motorcyclists. Although there are differences whether there is scope for harmonising motorcycle between each standard, some potentially would helmet standards as well as specialising standards make at best only a marginal difference in a crash. for specific environments. This paper will compare Some, such as Snell M2010 appear to be associated and contrast standards requirements and consider with heavier helmets. Oblique helmet testing can opportunities for improvements and international identify performance differences between helmets harmonisation. that are related to injury mechanisms not assessed directly by current standards. The climate and road A desktop review of standards, motorcycle helmet environment are issues that need to be considered and relevant biomechanical literature was and might lead to helmet specialisation as found in undertaken. The results of impact performance JIS T 8133. In other words, operators of low tests on 31 helmets that met at least AS/NZS 1698 powered motorcycles in hot and humid climates and combinations of other standards were assessed might have a helmet certified to a different part of a by standard certification. Tests included 2.5m flat common standard compared to operators of high and hazard anvil impacts with an ISO “M” powered motorcycles ridden at speed on major headform. Peak headform acceleration was roads. Also critical to the motorcyclists is the measured. Results from oblique impact tests on incorporation of a quality control system including motorcycle helmets were evaluated in terms of batch testing. identifying the benefits of such a test. The test rig consisted of a Hybrid III head and neck falling on These issues indicate opportunities exist for guided rails onto the top of a powered striker plate. harmonisation, specialisation and improvement in Tests were conducted up to a drop height of 1.5 m motorcycle helmet standards that will benefit and a horizontal speed of 35 km/h. Linear and motorcyclists, government, trade and road safety angular headform acceleration were evaluated. groups. There are many commonalities between each INTRODUCTION standard, but there are subtle to substantial differences also. All standards have tests of Ideally, the objective of a motorcycle helmet safety acceleration management, retention system strength standard is to provide performance criteria that and stability. No standard has a true oblique impact ensure a minimum level of head trauma reduction test and chin bar assessment is varied. There are no during a range of head impacts. Obviously this studies that compare the performance of helmets in reduction in head trauma is comparative, i.e. real world crashes by standard certification. There compared to a situation had the person not worn a were few significant differences in helmet helmet and was subjected to the same magnitude performance in lab tests by standard certification, head strike. A ‘safe’ helmet might thus be defined particularly when only full-face helmets were as one that provides ‘significant’ reduction in risk included in the analysis. There was an overall of head injury given the same impact conditions for correlation (Pearson Correlation = 0.60 (p<0.01)) a helmeted compared to a non-helmeted rider. However, what may be a significant reduction for between helmet mass and impact performance. one motorcycle stakeholder may not necessarily be Average maximum linear and angular headform sufficient for another, and may indeed be a accelerations for four helmets in oblique impact 2 hindrance to another (manufacturer/supplier), and tests were 150g (SD=30) and 9.5rad/s (SD=3.3), thus may vary depending on the stakeholder; e.g. a respectively. McIntosh 1 motorcyclist, a government road safety official, a injury the rate is approximately 41 times higher helmet manufacturer/supplier, an engineer, a trade than for car occupants [1]. This trend for official, etc. Those stakeholders concerned with motorcyclists is counter to the falling rates of safety would like to know how ‘safe’ a helmet is fatalities and serious injuries for other road users that meets the standard, and whether a helmet and similarly exists in the other countries [2]. As meeting one standard is ‘safer’ than one meeting the international and national markets for helmets another. Other stakeholders may see any onerous grow with increasing PTW use, and as ‘on-line’ safety requirements as financially detrimental to retail increases, there are many reasons to review their business, e.g. manufacturers/suppliers. the variety of helmet standards from different Obviously there are absolute and relative countries. comparisons that can be made. METHODS Public confidence in any standard that specifies a particular level of safety requirement is very A desktop review of six motorcycle helmet important. Considering that those members of the standards listed above, excluding BS, was public that care about safety may not be able to undertaken. The review covered technical aspects, assess the technical specifications of a standard, the epidemiological data, crash analyses and laboratory reputation of the organisation may be the single tests. most important factor in imparting public confidence that in the event of a crash, a helmet RESULTS that meets the standard’s safety performance criteria will protect a motorcyclist’s head. How the Impact performance standard is applied and the certification regimes are important in developing and maintaining Impact performance is assessed in all the six confidence in the standard, and may be standards using guided free fall impacts of a fundamental to protecting the motorcyclist’s head. helmeted headform onto an anvil. Centre of Gravity (CoG) headform acceleration parameters One or more of the following standards govern the are used to assess performance in all standards. performance of motorcycle helmets internationally. However, there is a great deal of variation in test Those standards are: specifications. • AS/NZS 1698 Protective helmets for vehicle Test Rig and Headforms users (Australia and New Zealand) Impacts can be conducted with two-wire guided • UN/ECE 22.05 Uniform provisions concerning drops with a unixial accelerometer, three-wire the approval of protective helmets and of their guided drops with a triaxial accelerometer visors for drivers and passengers of motorcycles (UN/ECE 22), or with a rail mounted device and and mopeds (Europe). uniaxial accelerometer. There are potential • Snell M2010: Standard for protective headgear differences in impact acceleration outcomes for use with motorcycles and other motorized between the guided (uniaxially restrained) impacts vehicles (USA) and the unrestrained UN/ECE 22 tests. • Snell 2005 Standard for protective headgear for use with motorcycles and other motorized The specific headform dimensions and sizing have vehicles (USA) not been compared, but appear similar except for • USA DOT 571.218 Standard No. 218; the DOT standard that still mandates DOT Motorcycle helmets (USA) headforms. All others mandate ISO headforms. • JIS T 8133 Protective helmets for motor vehicle ISO and DOT headforms are not equivalent in users (Japan) either mass or circumference. All impact tests utilise a rigid headform. UN/ECE 22 uses a full • BS 6658:1985 Specification for protective helmets for vehicle users headform compared to the half headform used in 1698 and Snell. There is national and international interest in Test Areas helmet standard comparisons, how the standards In brief, the test area covers the cranium, but not influence helmet performance and ultimately the face, and is similar between standards. The mitigate the risk of head injury for Powered Two Wheelers (PTW), i.e. motorcycle/moped riders and “Basic Plane” is common to all as is the “Frankfurt Plane”. There are some differences, e.g. the test pillion passengers. In Australia, it has been line for AS/NZS 1698 is lower than in the Snell reported that in 2008 motorcycles accounted for standards. only 1% of vehicle-kilometres, but 15% of motor vehicle user deaths being approximately 30 times the rate for car occupants. In regards to serious McIntosh 2 There is suggestion in some of the research Acceleration Requirements literature that there may be an interaction between CoG linear headform acceleration is measured in impact site and headform restraint in the specific all standards, either with a unixial accelerometer in test rig that effects headform acceleration. This is uniaxially restrained impacts or a triaxial the case, for example, in the unrestrained impact accelerometer in unrestrained impacts. There are when the centre of impact and centre of gravity potential differences in the measurements due to may not be aligned. the different methods. Although there are minor differences, the linear acceleration requirements in There is an option to test over a “protective lower five of the standards (1698, ECE, M2005, M2010 face cover”, i.e. chin bar, in UN/ECE 22. and JIS) are similar and in the range 275g to 300g. The DOT standard has a 400g requirement, which Flat Anvil Impacts appears to be the least stringent, until the “dwell All standards include impacts against a flat rigid time” limit of 2.0ms at 200g is considered. ECE anvil of the same dimension; around 130 mm also has a HIC 2400 requirement. Presumably, the diameter. UN/ECE 22 does not require two DOT requirements mimic the Wayne State successive impacts per impact site, unlike all other University head impact tolerance curve [4].