1 Cycling: the risks Richard J Hamilton a and JR Rollin Stott b On average, 140 cyclists are killed each year on Britain s roads and a further injured. About a third of those injured are children. This review examines the nature and circumstances of cycling injuries and contrasts them with the risks associated with other modes of transport. It looks at the effectiveness of cycle helmet use and suggests other measures to best reduce cycling injuries. Key words: accidents; bicycles; cycle helmets; cycling; fatalities; injuries; risks Cycle traf c Cycle traf c in Britain has fallen dramatically over the past 50 years (Figure 1). In 1949 bicycles accounted for 37% of all road traf c. By 1995 ± with the major exceptions of Oxford, Cambridge and York ± this had fallen to 1% (Hillman, 1994). Particularly noticeable, too, has been the decline in the number of children cycling. In 1971 three quarters of all junior school children cycled to school. By 1990 this had fallen by a half (Policy Studies Institute, 1990). In the same period road traf c increased in the UK by 104% (Department of Transport, 1998). Although bicycle ownership actually doubled between 1975 and 1995, in the same period, the average mileage cycled per person per year fell from 51 to 37 ± a drop of more than a quarter (Department of Transport, Local Government and the Regions, 2001). Two in every ve households own a bicycle, yet only 6% of the population regularly cycle, while a further 5% are occasional cyclists (Wardlaw, 2000). Commuting and leisure travel form the biggest bicycle user groups (Department for Transport, 1998a). Commuting accounts for nearly half of all the journeys made by bicycle. In 1995 it was estimated that 3% of the working population ( people) used a bicycle as their usual mode of travel to work. Most of these a University of Shef eld School of Medicine, Shef eld, UK; b Centre for Human Sciences, QinetiQ plc, Hants, UK. Address for correspondence: RJ Hamilton, Well Lane House, Lower Froyle, Alton, Hants GU34 4LP, UK. journeys are short; a quarter of them are less than a mile and another third between one and two miles, with a mean journey time of 15 minutes. In inner London and other metropolitan areas the mean journey time is 25 minutes (Department for Transport, 1998b). Leisure cycling accounts for a further 35% of all journeys made by bicycle. In the 1993 General Household Survey, cycling appeared in the top ve sporting activities and a fth of households reported recreational cycling in the past year. This was particularly true of households with children. Cycling accidents: facts and gures Each year about one in 40 of Britain s cyclists requires hospital treatment for injuries sustained in a cycling accident (Maimaris et al., 1994). Although cyclists comprise only 1% of road users, they account for 5% of all road fatalities ± and 7% of all serious injuries (Department for Transport, 2003). In absolute terms, cyclists form the fourth largest group of road accident casualties, after car occupants (48%), pedestrians (22%) and motorcycle=moped users (15%) (Department for Transport, 1998c). A more revealing index, however, is to compare the numbers in each category killed or seriously injured per 100 million vehicle kilometres travelled (Table 1). On this basis, motorcycles represent by far the most dangerous mode of transport, with 1510 casualties per billion passenger kilometres travelled. Cycling and walking are about half as dangerous, with car, taxi and bus travel roughly 30 times safer again. Per kilometre travelled, cyclists # Arnold = ta309oa
2 162 RJ Hamilton and JR Rollin Stott Figure 1 Cycle traf c in Great Britain. Source: Department for Transport, 1998d are 14 times more likely to be killed or seriously injured in road accidents than car drivers. It is interesting, too, to note that although the number of cyclists killed on the roads in Britain has declined by 43% between 1970 and 1995, cycle traf c has seen a similar (37%) fall during this period and the casualty rate per 100 million vehicle kilometres among cyclists actually increased ± by 17% (Department for Transport, 1998c). Accidents involving cars account for 44% of those cyclists killed and 73% of those seriously injured (Table 2). Accidents involving heavy goods vehicles account for the second largest proportion of casualties (25%), and a quarter of all cyclist fatalities ± most frequently as a result of left turning lorries. Ninety per cent of accidents involving cyclists, and 53% of fatalities, occur in built-up areas, in 30 mph zones, a fth of them in London (Department for Transport, 1998c). Two out of every three cycling accidents are caused by cyclist error. Three quarters of them are at road junctions. Roundabouts, too, are particularly dangerous for cyclists. Forty-four per cent of fatalities occur on nonbuilt-up roads, at traf c speeds in excess of 30 mph. About 80% of cycling accidents occur in daylight, between 8.00 and 9.00 a.m. and 3.00 and 6.00 p.m. ± when most cycling takes place ± with accidents rising to their highest during the summer when cycling s popularity peaks. Fifty-two per cent of child casualties and 37% of adult casualties are injured from May to August (Department for Transport, 1998c). Cyclist casualties are not evenly distributed by age and sex. Men account for 80% of all adult cycling casualties (Department for Transport, 1998c), largely a re ection of the fact that men do more than three times the annual cycle mileage of women (Department for Transport, 1998a). Even so, there is a small excess of male casualties per mile travelled. Nearly a third of those injured are children, the highest casualty rate for both sexes being between the ages of 12 and 15. Children in this age group have an accident rate of 22 per population, compared with the all ages rate per head of population of 7 per Injuries to both men and women decline with increasing age (Figure 2). Table 1 Passenger killed and seriously injured (KSI) rates by mode: 1994 Number KSI Billion passenger kilometres Pedal cycle Walk Motorcycle Car and taxi Bus and coach Source: Department for Transport, 1998e Rate: KSI per billion pass. kms
3 Cycling: the risks 163 Table 2 Other vehicles involved in bicycle accidents: 1994 Killed Seriously injured Number Percentage Number Percentage Total cyclist casualties No one else involved Accidents with a pedestrian Accidents with one other vehicle: Bicycle Two-wheeled motor vehicle Car Bus or coach Light goods vehicle Heavy goods vehicle Other vehicles Accidents with two or more other vehicles Source: Department for Transport, 1998e Types of accident and injury patterns Of cial statistics tend to underestimate the morbidity from cycle accidents. Of 86 children seen with bicycle related injuries in the UK, only two were recorded in police road traf c accident data and only 10 in hospital discharge records (Leonard et al., 1999). A similar disparity has been noted in a study from North Carolina (Stutts et al., 1990) in which only 10% of emergency room cases were duplicated on the state accident les. Figure 2 Pedal cyclist casualty rate per population by age and gender. Source: Department of the Environment, Transport and the Regions, 1998a
4 164 RJ Hamilton and JR Rollin Stott Mishaps from cycling occur frequently. In a questionnaire survey of US college students (Kruse and McBeath, 1980), 13% of cyclists had been involved in an accident in the previous year, a third of whom sustained an injury that required medical attention. The majority of cycle accidents do not involve another vehicle. About two thirds of cycle injuries treated in one Dutch hospital accident unit were in the category of single vehicle accidents (Kingma, 1994). Not surprisingly, injuries in this group tend to be less severe. More than 90% of fatalities to cyclists result from collision with another vehicle (Spence et al., 1993; Frank et al., 1995). Accidents involving child cyclists are often the result of the child playing, doing tricks, riding too fast or losing control. Cyclist error was considered to be the cause in 66% of accidents in children aged 8±12 years and no less than 87% of accidents in children less than eight years old (Simpson and Mineiro, 1992). The conclusion of this study was that no child under the age of eight should be allowed to cycle on a public road. For teenage and adult cyclists, accidents are more likely to involve collisions with other vehicles (Royal Society for the Prevention of Accidents, 2003). A study from Finland of the degree of disability resulting from cycle accidents (Olkkonen et al., 1993) examined the cases of 278 children and 264 adults seen in two Helsinki hospitals over a two-year period. Of those who required admission to hospital, some degree of disability was still present six months after the accident in 32% (11% of children, 47% of adults and 67% of elderly). Three per cent of adult inpatients suffered from permanent work disability. A study looking at deaths of cyclists in Greater London between 1985 and 1992 was able, tentatively, to group some of the 178 fatalities according to the manoeuvre being performed (Gilbert and McCarthy, 1994). In 30 cases (17%) a vehicle turned left across the cyclist s path ± in all but one of which the vehicle was a heavy goods vehicle. In a further four instances both the vehicle and the cyclist were apparently turning left together. Sixteen collisions (9%) occurred when the cyclist was on the nearside of a vehicle going straight ahead. A further 22 (12%) were hit from behind and eight were said to have swerved into a vehicle s path. Of the 35 children aged µ16, 14 (40%) were struck by a vehicle after cycling off the pavement. Four cyclists died after being hit by vehicle drivers opening their car doors and two died while cycling across zebra crossings. In addition to the 178 fatal accidents involving cyclists, ve pedestrians crossing the road and two motorcyclists died in collisions with cyclists. Another study in 1994 looked more speci cally at the injury patterns of cyclists attending the accident and emergency department at Addenbrooke s Hospital in Cambridge (Maimaris et al., 1994). Of the 1042 cases reviewed, the majority (63%) had fallen from their bicycles. Twenty-eight per cent had been in a collision with a motor vehicle, 7% in collision with another bicycle and 2% in collision with a pedestrian. Most of the attendees (70%) had soft tissue injuries only (abrasions, contusions and lacerations). Twentyeight per cent had received single fractures and=or dislocations, while 1% had multiple fractures and=or dislocations. Ten per cent had head injuries, 22% had injuries to the face or neck; 5% had injuries to their trunk; 45% received injuries to their arms and 25% to their legs. A number of studies have drawn attention to the risk of intra-abdominal injury from impact with bicycle handlebars. A retrospective study of 32 children injured by handlebars (Clarnette and Beasley, 1997) described trauma to the spleen, liver and pancreas, perforation of the bowel, urethral injury, and lacerations of the abdominal wall and inguinoscrotal region. Head injuries and cycle helmets According to the Royal Society for the Prevention of Accidents, 70% of cyclists killed on the road have had major head injuries, and over half of cyclists injured have head injuries (Royal Society for the Prevention of Accidents, 2003). In America, head injuries account for 85% of cycling related deaths and two thirds of cycling related hospital admissions (Wasserman et al., 1988). Several studies show that a signi cantly higher proportion of cyclists sustain head injuries in accidents than motorcyclists (Waters, 1986; Simpson et al., 1988). Of the 1042 patients in the Addenbrooke s study, 104 (10%) had received head injuries, of whom two died ± one due to an extensive head injury associated with a chest injury, the other due to a high cervical spine injury. A greater proportion of accidents involving motor vehicles resulted in head injuries (18%) than did other accidents (7%). The Addenbrooke s study looked closely at the bene t conferred by wearing cycle helmets and found that head injury (de ned as skull fracture, brain injury, loss of consciousness or post-traumatic amnesia) was
5 Cycling: the risks 165 sustained by 4% of helmet wearers, compared with 11% of non wearers ± a three-fold reduction that was present in all ages and for all accident types. None of the patients with skull fractures and severe brain injury, including the two deaths, had been wearing a helmet. A number of similar studies report comparable ndings. A meta-analysis of 11 studies carried out in Australia, the USA, Canada and the UK between 1987 and 1998 (Attewell et al., 2000) concluded that the summary odds ratio estimate of ef cacy was 0.40 (0.29, 0.55) for head injury, 0.42 (0.26, 0.67) for brain injury, 0.53 (0.39, 0.73) for facial injury and 0.27 (0.1, 0.71) for fatal injury. However, data from three studies that reported the incidence of neck injury suggested an unfavourable effect from helmet wearing with a summary odds ratio estimate of 1.36 (1.0, 1.86). A recent Cochrane Review of ve case controlled studies from different countries similarly concluded that cycle helmets decrease the risk of head and brain injury by between 65 and 88% and decrease the risk of facial injury by 65% (Thompson et al., 2000). A number of studies have looked at cycle helmets themselves. A study of 100 head injuries in Portsmouth found that 70% of the cyclists heads had hit the road rst. By plotting the sites of impact on the cyclists heads it was estimated that 50% would have been covered by a helmet (Worrell, 1987), though protection to the temporal area of the head is poor (McIntosh et al., 1998). Provided a helmet is designed to conform to current standards (for example EN 1078: 1997) (British Standards Institution, 1997), and is worn properly, it has been suggested that deaths due to head injuries could be reduced by as much as 90% (Dorsch et al., 1987). Butting heads Even so, helmet use remains a matter of controversy. The total number of deaths to cyclists has fallen almost continually, from 1536 in 1934 to 141 in 2002, in large part re ecting a decrease in cycle use (Department for Transport, 1998c). Equally, the proportion of cyclist casualties that involve fatal or serious injuries has also fallen, from 24% in 1974 (the rst year for which full statistics were available) to 18% in 1998 (Department for Transport, 1998c) (Figure 3). It is interesting to compare this fall with the rise in cycle helmet use. Over the decade to 1996, nationwide, cycle helmet use rose from close to zero to around 16%. In London cycle helmet use increased to around 40% Figure 3 UK cyclists killed or seriously injured ( )
6 166 RJ Hamilton and JR Rollin Stott (the highest in Britain) (Department for Transport, 1998c). Even so, cyclist casualty data for the UK shows no evidence of a `helmet effect, with accidents continuing to decline at the same rate as they had prior to helmet use becoming more popular. This nding is consistent with research in the USA (Rogers, 1988), Canada (Transport Canada, 2003), Australia (ARA- PRU, 1999) and New Zealand (Scuffham and Langley 1997), which found no evidence of any signi cant decrease in head injuries with increased helmet use in large population samples. Even in countries such as Australia and Canada, where, in some states, cycle helmet use has become mandatory, reported reductions in head injuries (Carr, 1995; Leblanc et al., 2002) have been countered by studies citing reduced cycle use following the introduction of legislation as the major cause (Wardlaw, 2002). In Australia, for example, admissions from head injury fell by 15±20% (Robinson, 1996b), but the level of cycling fell by 35% (Robinson, 1996a). Indeed, in 1988, the largest survey of cycling casualties ever undertaken in Britain concluded that increased helmet use correlated well with an increased risk of death (Rogers, 1988), leading some to argue that promoting cycle helmets confers a false sense of security to wearers and detracts from the real issues of promoting caution and good road sense and reducing traf c speeds (Franklin). Protecting cyclists Cyclists stand to gain more from road safety than any other road users. In a MORI poll, half of those surveyed said they would cycle for short journeys if roads were made safer (Naitonal Cycling Forum, 1999). While a cyclist has a 95% chance of surviving a collision with a car travelling at 20 mph, this is reduced to only 15% at 40 mph (Department of Transport, 1997). In York, for example, where 20% of all journeys are made by bicycle, a 30% reduction in casualties has been achieved by restricting vehicle speeds on 23 miles of residential roads (Hardwick Cycling Campaign, 2000). Similarly, in Denmark and the Netherlands, where 10% of all journeys are made by bicycle, despite little helmet use, cyclists form a much smaller proportion of those killed or injured on the road on account of safety programmes to reduce traf c speeds to 30 km=h and cycle lanes to separate cyclists from fast moving traf c (Department of Transport, 1997). Training for cyclists, particularly children, is also of great potential bene t. In Britain between and receive some sort of cycle training each year, although there is no national standard and quality and effectiveness may vary (Royal Society for the Prevention of Accidents, 2001). A study that compared the accident and casualty rates of trained and untrained children concluded that those trained are three times less likely to become a casualty than those who had not been trained (Transport Research Laboratory, 1989). Another study, however, cautioned that children who had taken a course may then be at greater risk, possibly because parents believed their children to be more competent than they were (Carlin, 1998). Discussion Many injury based studies have indicated that there is a protective effect from the wearing of a cycle helmet. It seems, at rst sight, dif cult to reconcile the conclusions of these injury based studies with population studies that have been unable to demonstrate any reduction in the incidence of death or serious injury to cyclists attributable to helmet wearing. In countries in which helmet use has been made compulsory, there is evidence of a fall in the numbers cycling. A possible reason for this is that the introduction of cycle helmets focuses public attention on the dangers of cycling, with the result that more cautious, risk averse cyclists, who are perhaps least likely to suffer an accident, are deterred from cycling. A comment, pertinent to this discussion, though made in connection with the introduction of smoke detectors and seat belt legislation, is that `unless compliance is virtually universal, the higher rates of death and injuries among high risk populations are likely to mask the effectiveness of the devices for the majority of people (McLoughlin et al., 1985). Given the high proportion of head injury related deaths and hospital admissions among cyclists, it seems eminently sensible to wear a good, well tted helmet. The British Medical Association has strongly recommended the wearing of cycle helmets by all cyclists, especially children, as part of a wider safe cycling strategy that includes cyclist training courses and cycle awareness in driver training and the Driving Test (Board of Education and Science, 1999). But the dangers of cycling need to be kept in context. Seventy per cent of British adults take exercise less than once a month (Hillsdon and Thorogood, 1996). According to
7 Cycling: the risks 167 the BMA, when considered alongside the dangers associated with inactivity, the overall health bene ts of cycling exceed the risks by a factor of 20 (Hillman, 1994). The government s White Paper A New Deal for Transport hopes to see a quadrupling of cycle use by 2012 (Department of the Environment, Transport and the Regions, 1998). To achieve this, cycling needs to be considered in the round. Improved security arrangements for bikes and adequate facilities to shower and change at work, for instance, are, ultimately, just as important as traf c calming measures, cycle lanes and promoting good road sense if cycling is to achieve its full potential. Acknowledgements We thank Alastair Hamilton for his help with graphics. References ARAPRU, (Australian Road Accident Prevention Research Unit.) An economic evaluation of the mandatory helmet legislation. Nedlands: University of Western Australia. Attewell R, Glase K, McFadden M Bicycle helmets and injury prevention: a formal review. Australian Transport Safety Bureau Road Safety report CR195. Board of Education and Science Cycle helmets. London: British Medical Association. British Standards Institution Helmets for pedal cyclists and for users of skateboardsand roller skates. BS EN Carlin J School based safety education and bicycle injuries in children: a case-controlled study. Injury Prevention 4: 22. Carr D et al Analysis of the bicycle helmet wearing law in Victoria during the rst four years. Monash Accident Research Centre. Report 76. Clarnette TD, Beasley SW Handlebar injuries in children: patterns and prevention. Aust NZ J Surg 67: 338±39. Department of Transport, Local Government and the Regions Focus on personal travel. London: The Stationery Of ce. stellent=groups=dft_transstats=documents=page=dft_ transstats_ pdf Department for Transport. 1998a. Cycling in Great Britain: characteristics of cyclists. Retrieved 15th May, 2004, from: stellent=groups=dft_transstats=documents=page= dft_transstats_ hcsp Department for Transport. 1998b. Cycling in Great Britain: cycling to work. Retrieved 15th May, 2004, from: transstats=documents=page=dft_transstats_ hcsp Department for Transport. 1998c. Pedal cyclists in road accidents: Great Britain. Retrieved 15th May, 2004, from: transstats=documents=page=dft_transstats_ hcsp Department for Transport Road accident casualties by road user type and severity, 1992±2002. Retrieved 15th May, 2004, from: ent=groups=dft_transstats=documents=page=dft_ transstats_ xls Department of Transport Killing speed and saving lives. Department of Transport Transport Statistics for Great Britain. Available on request from: DfT, Zone 2=17, Great Minster House, 76 Marsham St, London SW1P 4DR edition retrieved 15th May, 2004, from: transstats=documents=page=dft_transstats_ hcsp Department for Transport. 1998d. Cycling in Great Britain: cycle traf c. Retrieved 15th May, 2004, from: dft_transstats=documents=page=dft_transstats_ hcsp Departmentfor Transport. 1998e.Cycling in Great Britain: accidentsinvolving cyclists. Retrieved 15th May, 2004, from: transstats=documents=page=dft_transstats_ hcsp Department of the Environment, Transport and the Regions. 1998a. Pedal cyclists in road accidents: Great Britain Retrieved 15th May, 2004, from: transstats=documents=page=dft_transstats_ hcsp Department of the Environment, Transport and the Regions. 1998b. A new deal for transport: better deal for everyone. Transport White Paper. Dorsh MM, Woodward AJ, Somers RL Do bicycle helmets reduce severity of head injuries in real crashes? Accid Anal Prev 19: 188± 90. Frank E, Frankel P, Mullins RJ, Taylor N Injuries resulting from bicycle collisions. Acad Emerg Med 2: 200±03. Franklin J. Trends in cyclist casualties in Britain with increasing cycle helmet use. Retrieved 15th May, 2004, from: helmets=uktrends.pdf
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