Rapid Responses to:
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Rapid Responses: Rapid Responses published:
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Important considerations missing from study of motorcycle rider conspicuity and crash related injury.
- Joby Taylor (13 April 2004)
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Prevention is the best cure... but helmets come a close second
- Daniel P Edgcumbe (13 April 2004)
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Predator and prey
- Phillip J. Colquitt (14 April 2004)
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Motorcycle safety deserves further study - riding towards 2010
- Simon N Paul (15 April 2004)
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Re: Predator and prey
- Stephen CJ Love (15 April 2004)
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You are what you wear
- Peter M Brindle (15 April 2004)
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Author's reply
- Susan M Wells, Rod Jackson (10 May 2004)
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Confounding Factors
- Mir Islam Saeed, Aga Khan niversity (22 February 2005)
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Remember Your Physiology
- Thomas R. Piazza (13 July 2008)
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Polemics aside
- Mayank K. Kothari (29 May 2009)
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Re: Important considerations missing from study of motorcycle rider conspicuity and crash related injury.
- Frank M Lawton (5 July 2009)
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Joby Taylor, Urology Research Fellow Pinderfields Hospital, Wakefield, WF1 4DG
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Dear Editor, Although any study looking at how to reduce motorcycle casualties is to be welcomed, I feel the study from Wells et al has several significant flaws. The authors do not provide any information relating to the type of accident the 'case' patients were involved in. In particular, there is no indication whether the motorcyclist was at fault in the accident, or even whether another vehicle was involved. In these instances, the visibility of the motorcyclist is likely to be irrelevant. Similarly, for the 25.7% of accidents which occurred at night, clothing and helmet colour would have been irrelevant in terms of visibility. However, these accidents appear to have been included when analysing the effect of clothing and helmet colour. There is also no information given about the accident history of the control group, although this is a potential confounding factor. A significant proportion of motorcyclists will be involved in an accident at some point in their riding career, and it is highly likely that some of those identified as controls will have had an accident in the past. It is not clear whether such riders were excluded from the study. If this was not the case, then any comparisions drawn against this group will not be valid. The type of motorcycle being ridden is also not mentioned. Motorcycles and motorcyclists are far from a homogeneous group. Riders of 'race replica' machines are generally a very different group to those riding 'custom/cruiser' style motorcycles. Many years of personal experience suggests that the type of machine ridden is a better indicator of riding style and risk-taking than factors such as age, income or education. This is a significant factor, which does not appear to have been given sufficient attention. Before advocating 'high visibility' clothing, we must also consider what it actually is, and whether it will make a difference. As being visible depends on standing out from the background, no one colour is 'high visibility' in all situations. Indeed, in our increasingly garish urban landscape, plain dark colours may actually offer the greatest contrast. Finally, no amount of high visibility clothing will help if road users do not look before manoeuvring. The fact that the majority of accidents in this study took place at low speeds in good conditions suggests that inattention, rather than inconspicuity, may have played a greater part. Competing interests: The author has a black motorcycle helmet and dark blue/ black leathers. |
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Daniel P Edgcumbe, Fourth year medical student Christ's College, Cambridge
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The paper by Wells et al. brought to mind my experiences as a sixteen -year old aspiring to a medical career, working in the state trauma centre in Missouri. Naively expecting to be confronted by streams of patients presenting with gunshot wounds, virtually all of our workload consisted of dealing with the fallout from a local Goldwing motorcycle convention. Many of the casualties had needlessly severe injuries from their failure to even wear a protective helmet, let alone a conspicuously-coloured one. Competing interests: None declared |
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Phillip J. Colquitt, Technical Advisor Place of work: Self-employed
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As both car driver and motorcyclist, I feel both predator(car) and prey(motorcycle). I’m amazed how invisible motorcycles(prey) seem when I’m driving the car(predator). This is especially true at night when I cannot distinguish between the single headlight of a motorcycle coming toward me, and any one of a number of street lights lining the road(prey camouflaged). It’s as if the cycle with it’s one “eye” is invisible. If it had two “eyes”, spaced well apart(predator), not side by side as does occur on some cycle models, but more like the cars headlights, I suspect the motorcycle would be more recognisable/visible, and worthy of respect, as if competitor prey. But then prey may turn on feeble pedestrians. Competing interests: Remaining alive as prey |
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Simon N Paul, SpR Rheumatology & Rehabilitation St Thomas' Hospital, London , SE1 7EH
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Dear Editor, May I congratulate Wells et al [1] and the BMJ for illuminating the plight of motorised two wheelers, particularly just after National BikeSafe Weekend (an initiative run by Police Forces around the United Kingdom (UK) to help to lower the number of motorcycle rider casualties). I would like to make a few points, some of which echo those in The Police Riders Handbook [2]. Conspicuity can change rapidly: a white motorcycle against black tarmac is relatively visible, but the same machine against a white lorry merges. Indeed, any motorist may become invisible to another road user whose vision has been dazzled by bright sunlight irrespective of conspicuity measures. The authors’ ascertainment of headlight use to increase daytime visibility wasn't expanded upon. Bulb type and luminescence vary, and motorcyclists may ride with dipped or full beam headlights. These variables weren’t specifically addressed in the study. In fact, it has been suggested that voluntary use of daytime headlights might endanger those not using headlights, at least under laboratory conditions [3]. In the UK, a motorcyclist starting at the age of 17 will have had more than eight accidents by the age of 35[2] indicating that riders may not learn from their mistakes. With this in mind, the randomly selected control group may in fact have a significant and potentially confounding accident history. What a road user sees depends on a large extent to what they expect to see - the looking but not seeing phenomenon. It was interesting that most accidents occurred in fine daytime weather at lower speeds raising the potential attribution of overconfidence and inattention by crash victims and perpetrators. It mustn't be forgotten that a motorcyclist can increase their conspicuity in other ways. Police motorcyclists are taught to increase their profile when not engaged in high speed riding e.g., use of the horn to inform others of your presence, proper positioning for following and turns [2], reinforcing indicators with hand signals etc. The popularity of motorcycling has grown steadily since 1995 in the UK, the biggest increase being seen in motorcycles over 500cc capacity; these riders accounted for 75% of motorcycle fatalities in 2002 in an analysis of motorcycle fatalities by the Transport Research Laboratory [4]. Collision between a car and a motorcycle accounted for 74% of motorcyclist fatalities involving at least one other vehicle. Failure to observe the motorcycle or to judge its speed or path was also cited as a key contributory factor where drivers were judged to be primarily responsible for the fatality. Strategies to raise visibility of motorcyclists themselves, and raising awareness of motorcyclists by other road users clearly deserves further study if the Government is to meet its 2010 targets for increased road safety. A method of riding and driving offered by the Institute of Advanced Motorists [5] may indeed reduce accident rates - a factor which is increasingly recognised by motoring insurance companies. [1]Wells et al. Motorcycle rider conspicuity and crash related injury: case-control study. BMJ 2004;328:857-60. [2]Motorcycle Roadcraft. The Police Rider's handbook. 1996. Coyne. ISBN 011341143X. [3]Hole GJ, Tyrrell L. The influence of perceptual 'set' on the detection of motorcyclists using daytime lights. Ergonomics. 1995;38(7):1326-41 [4] www.dft.gov.uk Tomorrow's roads - safer for everyone: The first three year review. Theme 7: Safer motorcycling. [5] www.iam.org.uk Competing interests: None declared |
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Stephen CJ Love, Veterinarian Armidale NSW 2350 AUSTRALIA
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I read with interest the paper by Wells et al, and the rapid responses. I was a regular cyclist who wore very bright lycra clothing. Jokes aside, this was practical in terms of comfort and conspicuity. I am also a regular motorcyclist and wear a bright luminescent/fluoresecent vest (very 'uncool'!), a red or white helmet, and ride with my headlight on at all times. As a road-user from various angles (car and various non-car), I think conspicuity is important for all road users. I am surprised at how difficult it is to see non-light coloured cars and other users in low- light conditions. It also seems to me that most users give scant regard to their own conspicuity. I believe car drivers behave differently towards me depending on whether or not I wear my bright vest (I normally do). However, I am convinced that there is also the factor of 'cognition' as well as 'conspicuity'. Quite frequently cars -and pedestrians - will pull/walk out in front of me although I know they have seen me/looked directly at me. This, I am sure,is less likely to happen when I am in the car. So, I suspect that seeing or not seeing non-car road users is one factor; another is how car drivers and others process/respond to the information when they DO see non-car users. Riders, car drivers etc have to take reponsibility for their own safety as well. I believe inattention and incompetence are at least as important as speed, although the first two are harder to police and harder to raise revenue from (cf speeding fines). Roads and vehicles can be made more and more safe, but perhaps the most important factor is the person in the driver's/rider's seat. Alas, as a rider, you have to accept the need to be even more conscientious in thinking for yourself as well as other road users, especially car drivers. Stephen Love - NSW Australia Competing interests: Motorcyclist, cyclist, car driver and pedestrian |
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Peter M Brindle, General practitioner Corbett House Surgery, BRISTOL BS5 9QS
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The paper by Wells et al. does not seem to have considered an alternative to their conclusion that wearing high visibility clothing and light helmets reduces serious injuries or death from motorcycle crashes. As a regular motorcyclist, I aware that bikers who wear reflective clothing and white helmets ride in a very different way to bikers in black leathers with black helmets. They tend to be the “careful commuter” type (or policemen!) who is not bothered about looking cool and does not ride to show off. They also often have large panniers or a sensible top-box and ride BMWs. I am not convinced that the adjustments made in the analysis are sufficient to account for the “risk-taker” in black. My conclusion from the study: Bikers or riders (not drivers) who feel safe wearing high visibility clothing and light helmets also ride in such a way that makes them less likely to crash. Competing interests: I'm a biker with sensible panniers |
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Susan M Wells, Senior lecturer Clinical Epidemiology University of Auckland, New Zealand, Rod Jackson
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Author’s reply: Taylor suggests that injuries related to single vehicle crashes are not relevant to the analysis. In this study, we collected self-reported data on crash circumstances. Formal collision analysis and attribution of fault was not conducted. Over 70% of the crashes were multivehicle. We have analysed the data in two ways; for all crashes and then excluding single vehicle crashes where no other vehicle or road-user was involved. The findings were very similar. Taylor also suggests that injuries at night are irrelevant in terms of visibility. We do not agree and indeed the findings for white helmet and reflective clothing appear to strengthen as light conditions fall. We acknowledge that drivers’ inattention as well as not expecting to see a motorcyclist may contribute to crashes. However, being more visible against the background urban environment will enhance detection and thus potentially avert an injury crash whatever the other contributing causes. Most of the letters raise the concern of confounding with risk-taking riders being less likely to wear high visibility clothing or a white helmet. It should be noted that reflective or fluorescent clothing was not limited to vests or jackets but any piece of clothing having reflective or fluorescent properties –even a strip or decal. In a non-randomised study it is not possible to completely adjust for confounding. However as we had a comprehensive array of information about each study participant (eg, age, gender, alcohol consumption, insurance, licence status, cc rating, income, education, motorcycling experience, familiarity with the road etc) we were able to adjust directly and indirectly for risk-taking behaviour. We acknowledge the possibility that residual confounding could explain our findings. However, the effect estimate of the major conspicuity indicator (i.e. high visibility clothing OR = 0.63) remained substantial after adjusting for those who wear a white helmet. If the findings were mainly due to ‘safety-conscious’ confounding, we would have expected the effect estimate for high visibility clothing to be markedly attenuated when adjusted for helmet colour. Competing interests: None declared |
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Mir Islam Saeed, Post graduate student 0092, Aga Khan niversity
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Dear editor, I appreciate the hard works of the authors. I would like to know about the effect of mental health of a motorcycle rider. If there is slight problem, it will give rise to many crashes. Surely no one is not affected by daily problems. In addition, it should be identified what is the type and model of motorcycles(125cc. 250cc. 500cc and so on). Furthermore, they have collected data for the control group on telephones, in which case the interviewer is more reluctant and just wants to get rid of it. On the other hand, the effect of roadway maintenance and road side barriers are worthwhile. At the end I would like to be clear about the definitions of roads, too. Thanks
Competing interests: None declared |
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Thomas R. Piazza, military physician US Military
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How many times have you experienced, or heard a motorcyclist comment, "He looked right at me and pulled out in front of me!"? Human physiology is tantamount to this discussion, but I can not fully assimilate these study results with our basic physiology. Coming from a rigid military system where I must wear certain clothing items to be allowed on base (often annoying given the low base speeds and low population), I have pondered the question of conspicuity quite often. I am a FP physician with about 38 years of riding experience and the 2 times that I have had a car driver blatantly pull out in front of me have been on base, with my reflective vest on (daytime). Physiology, my friends, can explain a lot of this, but I have seen and read very little about this obvious item. When a car driver does the left/right check for oncoming traffic, the central facial object, the nose, blocks one eye's view at extremes of gaze (in my case, the object blocks a lot of view). Therefore one eye, e.g. the left in a leftward glance, is the only eye available to see an object. The physiological blind spot, created by the optic nerve, is not able to give any input to the brain. Our brains actually just fill in the details based on the information it has from the rest of the view. If a motorcycle is in the blind spot, it will absolutely and totally not be seen. So it's not that the car driver doesn't process the information of a motorcycle, he just doesn't see the motorcycle. The arc of non-vision due to the blind spot is constant, but the area blocked enlarges with distance. More death variables come in to play at this point based on motorcycle approach speed and distance from the car driver that doesn't see the rider. Truly, it wouldn't matter if the motorcycle rider was wearing white, black, reflective stripes, or nuclear material, the car driver's blind spot will not see it. Once the image on the retina is large enough to stimulate the rods or cones around the blind spot, then the object will be seen. The blind spot phenomenon is a basic and unchangeable physiologic truth. What I wrestle with is why would a study like this show that conspicuity actually does seem to make a difference? Perhaps a more conspicuous object stimulates the borders of the physiologic blind spot more than regular colors? Perhaps the variables of the car driver are just as important, and need to be controlled for, in a study (how much head turning is done, how long the sideways glance is held before an "all-clear" is registered by the brain?). As far as I am concerned, I chose to always wear a helmet and practice aggressive defensive driving; I always use a headlight during daytime and nighttime. As far as reflective gear is concerned, I am less convinced... To use the obligatory and tiresome phrase..."more studies are indicated." Competing interests: None declared |
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Mayank K. Kothari, Physician Des Moines, Iowa, USA
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This study must not be very visible, I ran into it while looking for a helmet. It seems strange that common sense would need a scientific study that in turn would have to be challenged just because it was a scientific study, all this in lawyer like manner. Smart people in the US proudly drive white cars because white is the most visible color and black the most invisible color under compromised lighting conditions. I firmly believe that anything that will make you stick out like a sore thumb on the road will do just that. This study merely propounds the common sense that increased visibility of the biker is more likely to save his life and decreased visibility is more likely to cost a life. I had found a black helmet earlier but I just changed my mind. Competing interests: I am a highly visible man |
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Frank M Lawton, Bike hirer Wellington 6011
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Hi i note one of the respondents to the study mentioned past riding experience as the key determinant of the likelihood of crashes ( or something to that effect) I agree with that.
I am one of only a few motorcycle hirers in new Zealand and I think the
only
person who hires to everyone ( ie I do not exclude under 25s) and I
also
think I am the only person hiring fast sport bikes.
My experience (from 2 years of hiring) is that the best groups to hire to
ie
who do not crash) were:
So while lights on, reflective gear and white helmets are all good ideas and should be taken up by riders it is regular riding that is the key. But as mentioned by others riding lots means as it is a numbers game you will eventually ?accidents" (car drivers just do not look at intersections) so these people may have "more" accidents than a control person I think? So any study needs to relate findings to km travelled of those that had and did not have accidents. I think that if like with like were compared some differences may be very small between groups. I also think the data may need to be tweaked a little for various factors eg some bikes always have their lights on - i think all BMws??) so may be the data should be adjusted for that fact? I think it also needs to be adjusted for "fault"?. Perhaps exclude all those where it was the rider's fault at intersections as that would seem to mean what they were wearing was irrelevant? Competing interests: None declared |
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