Development of a protective headband for car occupants

In 1997 McLean et al. (1997) demonstrated that energy absorbing headwear for car occupants might be effective in reducing the numbers of head injuries sustained by car occupants. The estimated benefits were greater than the estimated benefits of padding of the upper interior of vehicles to the requirements of the US Federal Motor Vehicle Safety Standard 201. This report investigates the suitability of selected materials for head protection, in the form of a headband that could be worn by car occupants.

The study is divided into three phases. Phase 1 surveys materials with a range of properties and impact behaviours. Impact tests provided the data by which assessments were made of the materials' effectiveness. The tests in this phase showed that a range of materials were able to attenuate the severity of the impact to a reasonable degree.

The materials identified in Phase 1 were tested further in Phase 2. Prototype headbands were constructed and attached to instrumented headforms which were dropped onto standard helmet testing anvils. The purpose of these tests was to examine the prototypes' response to concentrated loading. Several prototypes showed themselves to be unable to perform adequately in these tests; the anvils split or shattered the headband. Several prototype designs did perform well in Phase 2. These designs were tested in simulated head strikes with vehicle structures in Phase 3.

Phase 3 consisted of a series of preliminary tests in which a headform, protected by the prototype headband, was fired toward an interior structure that commonly causes head injury to car occupants in crashes.

Two prototype concepts appear worthy of further investigation. A headband constructed of polyurethane foam and a headband consisting of a cardboard honeycomb liner encased in a hard shell both significantly reduced the severity of impacts with the car structures. However, further investigation into optimising the selection of materials for their impact absorbing qualities and their comfort and durability in normal use is warranted.

These tests demonstrate that a headband for car occupants could significantly reduce the severity of certain head impacts in a crash. The best prototype headband reduced the HIC and peak acceleration values by over 60 percent in a standard test with the interior of the car. The reduced impact was approximately equivalent in severity to an unprotected impact with the structure at half the speed.
Conclusions and recommendations

The results from Phase 3 indicate that a headband can greatly reduce the severity of an impact to the head. HIC was reduced by 25 percent with the use of 25 mm of BB-38 polyurethane, and 67 percent with the honeycomb cardboard prototype, when compared with an impact with no headband. It is also noteworthy that the peak force produced in the test using the honeycomb headband was less than half the force produced by the headform alone. The honeycomb cardboard absorbed around three quarters of the impact energy before it began to bottom out.

The tests indicate that a crushable material, such as honeycomb, has the most effective characteristics for a headband. The ideal material would be one which

* Limits the peak force applied to the head
* Does so at a constant level from the initiation of the deformation
* Returns little energy to the head
* Does not bottom out

Practical considerations limit the thickness of the headband, so the challenge is to absorb the maximum amount of energy while limiting the peak loads transferred to the head of the wearer. In this way, the maximum amount of energy can be absorbed before the material bottoms out. Honeycomb is stiff initially when loaded, compared to polymer foams, but the peak load is limited by its inherent properties. The material stores little elastic energy, so the head of the wearer would be unlikely to rebound as severely as with some other materials.

One concern we had with the honeycomb cardboard is its durability. The material may deteriorate dut to environmental factors. There are several alternatives to paper, however, for the construction of a honeycomb structure. These include aluminium, polymers, and coated paper. These materials would give the same benefits as the honeycomb cardboard: energy absorption, force limiting characteristics, lightweight structure, but with the benefits of water resistance, and durability, in storage and handling.

The polyurethane headband also performed reasonably well in all phases of the tests. The BB-38 grade was the best performer of the polyurethanes. It may be possible to formulate a polyurethane with improved properties. However, at this time we have not seen a polyurethane which can match the honeycomb material in its behaviour.

We recommend that further investigation is made into materials of a honeycomb structure to find a material of the correct crushing strength and durability. We also recommend that prototypes be developed further to be included in a testing program that would include other vehicle structures tested over a range of velocities.

Community Attitudes to Road Safety State and Territory comparisons

The research shows significant differences in opinion between some States and Territories on major road safety issues such as speed, drink driving and fatigue.

People from the Northern Territory, for example, nominate speed less often than people from all the other States as the main factor in road crashes. They also mention drink driving more often than other States and Territories as the single most likely cause of road crashes.

On average, 10% of Australians report that they mostly drive 10 km/h or more above the speed limit. This number rises to 15% in the ACT. The research shows that breaking the speed limit is reported least often in Tasmania (3%).

The ACT also provides one of the highest perceptions that speed cameras and radar spots are easy to pick, along with Western Australia. CAS 13 shows 42% of the people surveyed in Western Australia and 33% in Victoria stating that they often receive advance warning about the location of speed cameras and radar spots, against a national average of 24%. Queensland (15%) and NSW (20%) are well below the national average on this measure.

While approval of a 50 km/h limit in residential areas is again expressed by a majority of people in all States and Territories, it remains highest in Queensland (73%), followed by NSW (70%) and Victoria (70%).

NSW and ACT residents report the lowest incidence of being breath tested in the last six months (one in five), compared with one third in each of the remaining locations.

After speed and drink driving, fatigue is consistently mentioned as the third most common cause of crashes. Fatigue is mentioned as a crash cause at higher levels than the national average in the ACT, Queensland and NSW. Significant falls in overall mention of fatigue have occurred, however, in the Northern Territory, South Australia and Tasmania.

Spontaneous reference to lack of concentration (the fourth most often nominated crash cause) tends to be most pronounced in South Australia, where 24% say it is the one main factor.

While there has been a national increase in the stated likelihood of wearing a rear seat belt, up from 85% last year to 89% in CAS 13, the Northern Territory (77%) is still below the national average (note that the reported rate has increased from 65% (CAS 12)).

On-road evaluations of a regulated hours transport service

The ultimate purpose of these studies is to support the development of alternative compliance approaches to the regulation of working hours. Rather than attempting to estimate the effectiveness of alternative work-rest schedules by applying theoretical knowledge of the area of fatigue, these studies have actually measured fatigue on-road under a range of different work-rest schedules.

This report describes an evaluation of the first pilot Fatigue Management Programme allowed under the Queensland Department of Transport alternative compliance programme. This alternative work-rest schedule differed from the regulated regime in that it allowed longer periods of active work without rest (6 hours instead of 5 hours) and allowed the mandatory six hours of continuous rest to be taken in two parts instead of one.

The results of the evaluation cast some doubts on the effectiveness of the alternative work-rest schedule and suggest that the balance between work and rest in the schedule needs to be re-examined. Although reported fatigue levels were not particularly high at any time in the study period, reaction speed became significantly slower on both laptop and palmtop versions of the Simple Reaction Time test across the study period. Furthermore, the results showed that reaction speed at the end of the study period had slowed to be poorer than the performance level found in drivers at 0.05% BAC. For the Mackworth Clock Vigilance test, performance also showed deterioration over the study period and showed some evidence of being poorer than the alcohol standardised performance at 0.05%BAC on occasions across the study period. For both tests, performance had deteriorated sufficiently to constitute a safety risk based on the community-accepted standard for on-road performance.

The results of the evaluation provide some hints about what aspects of the work-rest schedule needs to be changed. Drivers who did most work in this schedule rated themselves the most tired. This was also found in the first regulated regime evaluation (Williamson, Feyer, Finlay-Brown, & Friswell, in press, CR190) and consequently provides further evidence that long working hours are a serious risk factor for the experience of fatigue in driving

Most significantly, the length and quality of sleep and the number of breaks seem to be the major problems in this roster. The results show that the drivers who derived least benefit from their last rest were most likely to suffer effects on their capacity to perform. Many of the measures showed little or no improvement even after a sleep break, especially towards the end of the study period, suggesting a problem with either the positioning and/or the length of the breaks. This pattern was also seen in the simulated FMP evaluation described in the second report of the series (Williamson et al., in press, CR190) where by the second day of an extended work period (16 hours) breaks became increasingly useless in producing recovery of performance. Clearly, there needs to be a balance between the amount of work and the amount of rest needed to allow for proper recovery.

Not only is the length of break important, but the results also suggest that the quality of sleep obtained in the break is important. Drivers in this study were on-road for around twice as long as in the previous evaluations. It is likely that on-road rest is of inferior quality to rest obtained at home. This may be one of the reasons for the performance effects seen in this study. If this is the case, one of the suggested targets for improving this FMP schedule would be to reduce the amount of time away from home.

This report also describes a second evaluation of the current working hours regulations for managing fatigue. A similar evaluation was described in the second report (Williamson et al., in press, CR190) in which drivers were studied from the beginning of a period of days of work after at least a 24 hour break, for the period until their next 24 hour break. The current study was a replication of the first in a different company in which the working hours regulations are implemented slightly differently. Unlike the first evaluation, where drivers tended to work from a main company depot so that trips started and ended in the same place, in this second company, drivers were based considerable distances away from the company depot. This meant that the study was more difficult to organise and that many drivers in the study had been driving for a substantial period when they began the study so making it difficult to estimate fatigue and performance levels from maximally rested drivers.

Nevertheless, the results of the second working hours evaluation showed the same as the first one. The results showed no evidence of significant increases in fatigue or deterioration in performance capacity over a selected period of work. Fatigue ratings showed only minor, non-significant changes from the beginning of the study period across the first work period for the remainder of the study period. Similarly, Simple Reaction Time and Mackworth Clock Vigilance test measures also showed only slight changes across the study milestones. These results need to be interpreted with some caution, however. For many drivers in the study, it was not possible to measure their performance when they were maximally rested. This means that the lack of change over the study period may have been because drivers were tired on both occasions. Using the alcohol performance standards, however, it was possible to conclude that performance was within the estimated performance standard for most drivers so suggesting that the roster is allowing adequate rest to balance work.

Like the previous evaluation, however, this study showed that long periods of work, inadequate breaks and poor quality sleep will produce adverse effects on performance. Drivers who did the longest working hours and especially night work showed the slowed reaction time in the Simple Reaction Time test. Similarly, where drivers had fewer breaks or poorer quality sleep in their breaks, their ability to maintain consistent and accurate performance on the Mackworth Clock Vigilance test was adversely affected.

These studies have reinforced again the usefulness of taking this evaluation and model-building approach to the problem of fatigue management in the long distance road transport industry. The techniques developed for the approach have demonstrated their usefulness for detecting fatigue effects in this study as well as the previous ones. The results have reinforced the conclusions of the earlier evaluation of the current working hours regime by showing that there appear to be no major effects of fatigue. They show, however, that where drivers work to the upper limits of the current regime, the risk of fatigue effects are significantly increased. The results also demonstrate the problems of an alternative compliance approach to fatigue management and point out the general areas for improvement in the work-rest schedule.

Road Car Transport Trauma and Overseas Born Road Users

The purpose of this study was to examine whether residents born overseas had higher rates of death and hospital separation due to road crashes than those born in Australia. This study followed earlier research into the driving behaviour among women in Australia, where the self reported rate of motor vehicle accidents was significantly higher among those born in a non-English speaking country (BNESC), (Dobson, Brown, Ball, Powers & McFadden, 1999).

The study categorised those born overseas according to language of country of birth (English speaking, non-English speaking) and road convention in country of birth (left hand side, right hand side). Classification by language replicated the categorisation in the earlier study noted above. The cultural differences between Australia and non-English speaking countries are likely to be greater than those between Australia and other English speaking countries and these may contribute to differences in involvement in road crashes. A more obvious contributor to road safety outcomes concerns the road convention in the country of origin. Obviously, those familiar with traffic travelling on the left hand side of the road will have less difficulty in adapting to Australian conditions than those familiar with travel on the right hand side.

Data on deaths that occurred in Australia between 1994 and 1997 and hospital separations that occurred in New South Wales between 1 July 1995 and 30 June 1997 due to road crashes were analysed. The rates of death and hospital separation for various migrant groups adjusted for age and area of residence (country versus city) were calculated, using population data from the 1996 census.

There is no evidence to suggest that overseas born drivers are more likely than Australian born drivers to be involved in crashes resulting in death or serious injury. Overall, the mortality and hospital separation rates for those born overseas tended to be equal to or better than those for Australian drivers. In particular, female drivers born overseas tend to have lower rates of hospitalisation regardless of language or road convention. Male drivers from English speaking countries or those that drive on the left hand side of the road also have lower rates.

The most concerning results of the study were with respect to pedestrians. Pedestrians born in other English speaking and non-English speaking countries where the convention is to drive on the left hand side of the road were equally safe or safer than Australian born pedestrians. On the other hand, pedestrians born in countries with a right side driving convention were at significantly greater risk of being hospitalised or dying on the road relative to Australian born pedestrians. Road convention appears to have a greater influence on pedestrian safety than language in country of origin.

The difference in risk for the overseas born and locally born population is greatest for the 60 years and over age groups. Those in this age group who were born in countries that drive on the right hand side have at least 10 times the risk of being killed or injured as pedestrians when compared to the Australian born. The actual impact of this increased risk is exacerbated by demographic patterns. Pedestrian casualties for the overseas born comprised more older people than for the Australian born. Of the pedestrian deaths involving those from countries driving on the right hand side of the road 70% were 60 years of age or older compared to 32% for Australian born. The difference for hospital separations is less marked but in the same direction.

Results for passengers are of less interest as passengers rarely influence crash outcomes. The results suggest that males born overseas are under represented as passengers in terms of hospital admissions. In contrast female passengers are over represented in both deaths and hospital admissions when these women are from non-English speaking countries or from those that drive on the right hand side. This finding probably reflects differences in travel patterns for these groups.

These results rely on the assumption that driver licence rates, passenger behaviour and pedestrian activity are the same for both overseas and locally born residents. For example, if people born overseas are less likely to hold a licence the number of road crashes per 100,000 population could appear low while the number per licensed driver is actually as high or higher than that for Australian born drivers. Similarly if one group of pedestrians travels further, then their greater exposure to injury is not reflected in the rate of death or injury per capita.

It is of concern that while overseas born drivers are not over represented in trauma statistics, overseas born pedestrians clearly are. The reason for this may in part lie with the influence of spatial indicators on road related behaviour. Regardless of the side of the road on which traffic travels, there are various spatial cues which assist the driver. In the first place, the driver is always seated closest to the centre line of the road. Travelling with the driver adjacent to the curb is a clear indication that something is wrong. Furthermore, if a driver inadvertently strays to the wrong side of the road, oncoming traffic will be seen approaching directly prompting avoidance manoeuvres. Pedestrians lack such spatial cues to guide their behaviour. The pedestrian who looks the wrong way will be struck by a car that is not seen or even anticipated.

It is probable that pedestrian behaviour (looking to the left or to the right) is learnt at an early age and may be difficult to change. Certainly, educational material could be directed to increase public awareness of the issue for those most at risk. There is an obvious place for appropriate community based organisations to play a lead role in any communication strategy.

On the basis of these findings, it would appear that if the relative safety of those born in countries that drive on the right hand side of the road could be improved to match those born in Australia then 34 pedestrian lives would be saved each year and many more hospital admissions avoided. This is approximately a 10% reduction in the total pedestrian road toll for 2000.