Bicycle safety
From Wikipedia, the free encyclopedia
Bicycle safety is the use of practices designed to reduce risk associated with cycling. Some of this subject matter is controversial: for example, neither bicycle helmets nor cyclepaths have been proven to deliver improved safety.
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[edit] Bicycle crashes
The first recorded bicycle accident is probably the 1842 collision between Kirkpatrick McMillan, an early rider of the velocipede, and a young girl in the crowd that had gathered to witness his arrival in Glasgow after a 40-mile ride from his home[1].
Causes of crashes vary according to local conditions. Research in the UK has found that between 60% and 85% of serious cyclist injuries are the result of negligence by a motor driver,[2] while a study conducted in 2000 by SWOV (Institute for Road Safety Research) in the Netherlands found that single bicycle accidents accounted for 47% of all bicycle accidents, collisions with obstacles and animals accounted for 12%, and collisions with other road users accounted for 40% (with the remaining 1% having unknown or unclassified cause).
[edit] Defining danger
Using one meaning of the word, cycling is not dangerous. There are some injuries and a few very rare fatalities caused to non-cyclists by cyclists, largely due to cycling on the pavement (UK) or a sidewalk (USA), but since this is itself a response to the danger posed by others to cyclists this is arguably not an inherent danger of cycling. Off-road cycling is more dangerous, but not unusually so when compared with similar outdoor activities such as hiking.
To consider it from another perspective, cycling is dangerous because cyclists, like pedestrians, are especially vulnerable to the negligent actions of others - specifically, drivers of heavy motor vehicles. It is indicative of the unusual power of the motor vehicle lobby in Western politics that, against normal practice, the majority of proposed solutions to this problem take the form of restrictions imposed on the bicyclist (who is endangered) rather than the motorist (who poses the danger).
Actuarial data and governmental statistics both show that cycling is a relatively safe activity overall, the risk being comparable with that of walking near traffic. Injuries for pedestrians and cyclists also follow very similar patterns. In both cases the dominant source of injury is collision with heavy motor vehicles, with pedestrians apparently being significantly more likely to be blamed for such incidents than cyclists (perhaps due to how often people walk while under the influence of alcohol). These figures should be treated with caution: exposure data is notoriously difficult to assess, and findings of blame are also inclined to be arbitrary with courts widely perceived as giving undue weight to the claims of motorists.
The boundaries are blurred due to cyclists' reputation for flouting the rules of the road. Some of this is deserved, some is not. In its Research Report 549 of 2003, the Transport Research Laboratory noted that:
A key finding which should be noted was that, when commenting on the scenarios it was usually the behaviour of the cyclist that was criticised – no matter how small the misdemeanour. Few links were made between the cyclist’s behaviour and any external influences that could be affecting their choice of behaviour; i.e. the respondents’ comments indicated that they thought the cyclist’s actions were inherent and dispositional behaviours. In contrast, the motorists’ misdemeanours were excused or justified in terms of the situational influences. As this tendency seemed to continue across the groups and the individual depth interviews and was unprompted, it is unlikely that group dynamics had any significant effect on this finding. [...] This aligns with the psychological prediction of targeting of members of an ‘out group’.
The case for strictly regulating cyclists is inherently weak, since cycling does not pose an extraordinary danger to others or their property (unlike motoring). There is no credible evidence that cyclists are more unruly than any other road user group; the offences for which they are criticized (riding on footways, running stop signs and traffic signals) are not unique to them, and drivers, for example, freely admit to committing other offences such as speeding.
Measures to encourage cycling are generally seen as desirable from a public policy standpoint due to health benefits (for cyclists), reduced danger (to others and their property), and lower environmental impact. Yet the public is often urged (and in some cases even compelled) by the government to restrict their cycling. The root cause of this inconsistency is a matter of some debate[3].
[edit] Defining safety
Fundamentally, safety is the reduction of risk. Safety interventions divide broadly into primary and secondary safety. Primary safety is the active reduction of risk; secondary safety is measures taken to mitigate the consequences of risk. For example, brakes are a primary safety measure, seat belts are a secondary safety measure. The principles of risk management dictate that risk should be controlled first by reduction of risk at source, second by reducing of exposure to risk and third, only if the other two fail, by use of personal protective equipment.
In regards to road-traffic safety for cyclists (and indeed for pedestrians), the first option is seen by most Western governments as politically inexpedient. Notwithstanding the fact that a clear majority of serious cyclist injuries are caused by motorist negligence (estimates varying between 2/3 and 9/10), most opinion-formers are drivers of heavy motor vehicles. The media is often strongly pro-motorist, perhaps due to the substantial advertising spend of the motor industry. This bias existed well before the car became a mass means of transportation. As long ago as the early 1930s there were efforts to clear cyclists off the roads to make way for private cars, then the preserve of the elite. These were successful in Germany, then an authoritarian regime, and spread during the war to German-occupied countries such as the Netherlands, but was resisted in other countries. In England, Commissioner of Police for the Metropolis, H Alker Tripp commented that pedestrians and cyclists could never share the roads safely with motor traffic, so should be segregated. The implied loss of commons has been described as creating "bicycle Bantustans".
[edit] Primary safety
The state of knowledge regarding primary safety has advanced significantly through programmes such as Effective Cycling and the development of Britain's new National Standards for cycle training. In addition to technical improvements in brakes, tyres and bicycle construction generally (for example, it is now rare for a chain to snap and throw the rider when accelerating away from a stop), there are well-understood behavioural models which actively manage the risk posed by others.
Most important among these is the understanding of road position. In the 1960s and 1970s it was common for novice cyclists to be instructed to ride as close to the nearside kerb as possible. It is now understood that this encourages dangerous overtaking, by acting as a tacit invitation to overtake and by giving a false impression of the amount of space a cyclist needs. Modern practice places the cyclist much further into the traffic stream.
[edit] Safe Cycling
Much of what is covered here will be found in the syllabus of a thorough cycling course. Cycle training has developed very considerably in the last couple of decades, and any new or returning cyclist, adult or child, is likely to benefit from formal training from an accredited instructor. At the very least it's worth riding out with an experienced "bike buddy" who can help you get started.
[edit] Maintenance
First and foremost a cyclist needs a well maintained and functional machine. The bicycle is one of the few consumer durables still intended to be maintainable by the owner: most cycle maintenance is simple and requires only basic tools. At the very least the rider should regularly check safety-critical components:
- Brakes: the front brake should be capable of locking the front wheel so that if the bike is pushed forwards, the rear wheel lifts; the rear brake should be capable of skidding the rear wheel.
- Headset: with the front brake firmly on, rock the bike forwards and backwards. If you feel a clunk as the bike moves, and the handlebars move around, then the headset probably needs adjusting or replacing.
- Tires: inspect your tires regularly for cuts and wear. Worn tires can blow out, with perilous consequences. They also puncture more readily. Check that your tires are pumped up enough. Pinch the tire between thumb and forefinger: It should feel hard. Mountain bike tires typically run at about 45psi, road bike tires at anything up to 120psi. Do not use garage forecourt airlines gas station air compressors) to inflate bike tires, use a proper pump preferably with a pressure gauge. Over-inflated tires can lift off the rim and burst. Under-inflated tires compromise control and can result in pinch flats, also known as snakebite punctures for their characteristic double holes.
- Wheels: In turn, lift each end of the bike and spin the wheel. It should spin freely and the rim should remain roughly the same distance from the brake blocks. A wheel which is badly out of true may indicate a broken spoke - this should be fixed as soon as possible or else more spokes (or the whole wheel) will probably soon fail. Try to move the rim from side to side. If it moves or you feel a clunk, then the bearings may be worn and should be checked. If the wheel feels gritty as it spins, or rumbles, the bearings are probably damaged.
- Handlebars: stand in front of the bike, facing towards it; hold the front wheel between your legs; grab the handlebars and try to turn. If the bars twist on the stem, tighten them.
- General: if you have mudguards (fenders), a rack, a chain guard or any other equipment attached to your bike, give it a good rattle from time to time and check that it is still securely fixed. Loose mudguards, for example, can go in your wheel and bring you down.
[edit] Lights & conspicuity
The general consensus is that if you ride after dark you should use lights. This a legal requirement in most places. It is also generally recommended that you dress to be seen, especially in poor weather. Although this consensus is broad-based, it is largely intuitive and there is little, if any, hard evidence to support it.
[edit] Road position
Best practice puts the cyclist's wheels more or less where the nearside wheels of the motor traffic would normally go (the "secondary riding position") or, at points of particular danger such as junctions and width restrictions, in the centre of the lane (the "primary riding position" or "taking the lane").
The majority, 73% according to UK data, of car/cyclist collisions occur at junctions or "junction type" locations. Analysis of T-junction [4] and Roundabout[5] collisions has indicated that failure to yield by entering motorists is a significant accident type. Other significant collision types involve turning-motorists failing to yield to oncoming cyclists and so-called "hook" or "overtake and turn" type manoeuvres. Expert opinion has it that, having taken due account of the nature and speed of any following traffic, cyclists may best protect themselves from such collisions by adopting a prominent road position approaching junctions.
This has two functions: first, it places the cyclist where drivers are actively looking. Second, motorists must "overtake" so may be discouraged from simply driving past the cyclist and then turning across them. Similarly, away from junctions, a prominent position correctly communicates the space the cyclist needs and makes passing a matter of overtaking properly, rather than squeezing past. Additionally most minor injuries to cyclists, possibly up to 85%, result from simple falls[6]. Arguably, keeping out from the kerb also keeps the cyclist away from potential hazards such as drainage grates, gutters, potholes, roadside debris, loose gravel and glass etc. However, a sense of caution is required, what works in urban conditions for someone like a young adult sports-cyclist may not work for someone else who is less able or experienced. As with all road users, cyclists should try to exercise common sense and use gradual experience to build up to new traffic situations.
The advice on positioning contrasts with a lot of information historically given out in basic cycle training for children, and appears to conflict with the vehicle codes in a number of jurisdictions, which will often require a cyclist to ride as far to the right (in left-hand drive countries) as possible. Many drivers also feel that a cyclist has no right to use the road, and that cyclists should be as close to the margin as possible so as not to interfere with their speedy passage. It is worth remembering that no highway code is intended to actively endanger life; the wording may be careless or possibly ignorant but should be interpreted as meaning as far toward the margin as is consistent with safety - and that might mean in the middle of the lane.
[edit] Road Hazards
[edit] Metal
Metal drain covers are often placed in the part of the road where cyclists ride, particularly at junctions. These become slippery in wet weather especially after a dry period when rubber particles and a film of oil have built up.
A variant on this is the drainage grate with slots that run parallel to the direction of travel. These can easily grab a cycle wheel and cause a crash. There are several alternative bicycle-safe designs that use holes that will not grab a bicycle wheel; best practice indicates that cyclists should in any case ride further out than the drainage grates.
Railway tracks crossing the road are particularly hazardous, combining polished metal surfaces and deep channels that can trap a wheel and throw the rider off the bike. The worst case is when the tracks cross the roadway at an angle, which makes it even easier for the front wheel to be thrown off course. The standard advice is to cross tracks at a right angle, or as near to a right angle as possible.
[edit] Speed bumps
Speed bumps used as traffic calming devices on public roads are designed according to an accepted standard and present little hazard to bicyclists. Some of the desirable design features are a smooth transition from the road surface and a limited slope. In contrast, speed bumps on private or non-public roads and parking lots don't have to meet standards, and are therefore usually of a more varied design and could present hazards to cyclists. One example is a bolt-on rubber speed bump with an abrupt edge that can cause a bicycle front wheel to turn sharply and eject the cyclist.
[edit] Slippery (Icy) Conditions
On very slippery surfaces, even a minor lean to one side can cause the whole bike to slip, and the biker to fall over. However, it is still possible to bike in these conditions. In fact, depending on the surface properties of the road or pathway, the likelihood of slipping into an accident on a bike is arguably less than that of in a car or on foot. However, a winter rider must do things differently than a summer rider.
First, the seat of the bike should be lowered so that both the rider's feet can touch the ground at the same time. This is done so that, if the bike does slip, then the rider can support the bike with his legs. Having both feet down creates a stable structure. Note that lowering the seat will make riding more difficult, as the rider cannot fully extend his legs when pedalling. Also, the rider should not use any toe clips or toe cages on the pedals, so that neither foot gets caught on the pedal in situations when a leg needs to be extended on the ground.
When biking in slippery conditions, it is sometimes recommended to use the rear brakes rather than the front ones. Note, however, that in non-slippery conditions, it is recommended that the front brakes are always used. The use of rear brakes in slippery conditions is for the same reason that cars have anti-lock brakes on their front wheels; since the front wheels are used for steering, then the rider/driver is unable to steer when these wheels lock up. Thus, it is recommended to only use the rear brakes when possible, in case the bike starts to slip and a course adjustment is necessary.
Lastly, studded tires are a wise investment in climates with prolonged slippery conditions. These tires add much-needed traction to the bike itself. In most locations with long winters, any reputable bike shop will sell studded tires.
[edit] Braking
As a moving vehicle brakes, the vehicle applies a forward force on the road, and the road applies an equal and opposite backward force on the wheel. When braking a bike at the absolute maximum possible, all the force has transferred to the front wheel and the rear wheel is on the point of lifting. It follows from this that the front brake should be used for stopping, not the rear. Many riders are reluctant to use the front brake fully for fear of going over the handlebars, and some old-fashioned training encouraged use of the back brake. Modern direct-pull cantilever brakes (e.g. Shimano's V-brake) are very effective. Riders who are unfamiliar with these brakes might easily apply more brake force than intended and lose control. Novice or returning riders should learn how to brake properly using primarily the front brake. One exception, when rear brakes should be used over front brakes, is in very slippery road conditions. In these circumstances, if the front tire locks up (because of braking), then it will not be able to stear the bike. Using the rear brake allows the rider to steer while braking. A prudent rider practices braking and turning until they have a good feel for how the bike will handle under heavy braking. On a well-maintained bike and having practiced properly it is very unlikely that a rider will go over the handlebars when braking.
Rim brakes generate heat. On long descents, or stopping from speed, this causes the brakes to lose efficacy - this is known as brake fade (cars get this too). If the rider sits up straight, air resistance will provide much of the braking force, and the cycle will reach a limiting speed of under 25mph except on the steepest of roads. The rear brake can also be used to gently slow a descent. The front brake should be used in combination with the rear so as to avoid overheating either one. Disc brakes are less prone to this, but it does still happen.
Water degrades braking efficiency. Rim brakes in particular will not work until the rim is dry, potentially losing valuable seconds. Always brake early in wet weather, and if the roads have recently been dry watch out for oil lifted from the road surface. Steel rims become close to frictionless in the wet. When steel rims were the norm it was possible to buy leather brake blocks which worked in the wet; these are now very hard to find. In practice the best thing to do with a steel rim may be to replace it with an aluminum one.
[edit] Bike fit
It is common for parents to buy a bike that is too big, in the knowledge that a child will grow. This can make it very difficult for the child to control the bike properly - in most cases it would be better to buy a second-hand bike the right size than a new one with "room for growth," which is, in reality, too big.
In adults the biggest fault is usually having the saddle too low, but this is mainly a problem of comfort and health rather than safety. The best advice when buying a bike is to go to a specialist bike shop and take advice.
[edit] Cycle paths
Cycle paths have a chequered history. Standards of design, construction and maintenance vary widely.
Statistically, cycle paths have an indifferent safety record. This is largely a result of loss of priority and conflicts at junctions. In general, a cycle path reduces risk between junctions, but greatly increases danger at junctions. The balance of danger will depend on the frequency of junctions and other crossings. Width is also an issue: the minimum recommended width for a cycle path is around 2m, but some are very much narrower. Maintenance can also be patchy; glass and potholes are common. Shared-use facilities, shared with pedestrians, are generally considered to be least satisfactory.
On-road cycle lanes are also a mixed blessing. Some are well designed, and the advanced stop line (a section of road which allows cyclists to clear junctions ahead of motor traffic) is generally appreciated by cyclists. But some cycle lanes are too narrow, disappear at the point of greatest danger, take the rider out of the line of sight at junctions, are ill-maintained or littered with debris. For the most part, road cyclists agree that the main carriageway is preferable both for visibility and because the passage of traffic sweeps away any debris.
It should be remembered that, for the most part, cyclists are not actually asking for extra facilities. Most utility cyclists actually want nothing more than a bit of consideration.
[edit] Helmets
The subject of cycle helmets is controversial. Some evidence suggests that helmeted riders are less likely to suffer head injury; other evidence suggests the opposite. Even when cycle helmet use has risen steeply due to laws that require it, it has not been demonstrated that there is a correlation between helmet use and reduction in head injuries. Recent analysis supports the conclusion of Spaite et al. that much of the effect attributed to helmets in case-control studies may be due to behavioural differences in the types of cyclists who choose to wear or not wear them. In a low speed crash, a cyclist might benefit from wearing a helmet but the theory of risk compensation suggests that the fact of wearing one may subtly influence cyclists' riding by making them less careful. In a more serious crash, especially if a motor vehicle is involved, it is unlikely that a helmet will make a significant difference. One study found that 16 of 20 cyclist fatalities whose primary cause of death was listed as head injury also had other fatal injuries. Of the remaining four, at least one rider had been helmeted at the time[7].
No cycle helmet is designed to be effective in high speed collisions or those involving motor vehicles, yet where helmet laws have been passed they have always been for road cycling only. This is considered by some to be victim blaming or a smokescreen to obscure the danger posed to cyclists by motor traffic. Helmets may mitigate some injuries during a collision, but cannot prevent collisions from happening.
[edit] See also
[edit] External links
- How to reduce the odds of a collision with other vehicle operators
[edit] References
- ^ Kirkpatrick McMillan and the Bicycle
- ^ Davis R, Death on the Streets: Cars and the mythology of road safety
- ^ Forester, John. Review of: Bicycle-Safety-Related Research Synthesis. Retrieved on May 16, 2006.
- ^ Irish Junction Design Practice. Galway Cycling Campaign. Retrieved on May 16, 2006.
- ^ Multilane Roundabouts. Galway Cycling Campaign. Retrieved on May 16, 2006.
- ^ [http://www.cycle-helmets.com/bicycle_crashes.html Bicycle Crashes and Injuries in Western Australia]. cycle-helmets.com. Retrieved on August 27, 2006.
- ^ Sage MD (December 25, 1985). "Fatal injuries to bicycle riders in Auckland". NZ Med J 98 (793).
