Motorcycles

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Motorcycles

Motorcycle use is the most dangerous mode of road travel. More than 6500 motorised two wheeler users die each year in the EU (15) and the risk of death for motorcyclists is 20 times that of car occupants. Motorcycles tend to have much higher power-to-weight ratios than cars, and increasing numbers of motorcycles are capable of very high speeds and accelerations. Apart from their inherent instability, compared with other motorised vehicles, motorised two-wheelers, because of their size and shape, are less easy to see than other motor vehicles and have poor visibility in daytime. Various attempts have been made to improve the general stability of motorcycle through concepts such as the BMW C1.

In the World Report, the World Health Organisation and World Bank have advised that care should be taken to avoid the adoption of policies which could encourage the growth of motorized two-wheeler traffic by giving advantages to motorized two-wheeler users. Research shows that in addition to managing exposure to risk, vehicle engineering and protective equipment measures play a particularly important role in reducing injuries and crashes amongst motorised two wheeler users.

Notwithstanding the high risks associated with motorcycle use, relatively little research on motorcycle safety design has been carried out. However, with the increasing popularity of this transport mode and increased casualty levels, new EU and national attention is currently being given to this area.

Exposure measures

Restricting engine capacity for novice motorcyclists from 250cc to 125cc, accompanied by a limitation on the maximum power output (to 9 kW) has proved to be a successful measure in the United Kingdom in the early 1980s. Many inexperienced motorcyclists transferred to less powerful vehicles, leading to an estimated 25% reduction in casualties among young motorcyclists. Significantly greater crash risk is associated with larger motorcycles, despite even when these machines are ridden by more experienced riders.

However, many studies of the relationship between engine size and crash risk have failed to control for confounding variables which has had a major influence on the results of studies. For example, a study by Ingebrigtsen (1990), showed only weak effects of engine size once a host of other variables influencing the crash rate had been taken into account.

Japan imposes limits, for safety reasons, on the engine size and performance of large motorcycles used domestically. For most exported motorcycles, outputs of 75-90 brake horse power (56 -67 kW) or even 130 brake horse power (97 kW) are common with top speeds reaching almost 322 km/h.

Crash avoidance measures

Daytime Running Lights

The objective of mandatory use of daytime running lights for motorcycles is to reduce the number of crashes by making it easier to see motorcycles in traffic. The use of daytime running lights (generally lowbeam) is compulsory in several EU Member States (e.g. Austria, Germany, Belgium, France, Spain and Portugal). Some of these require action on the part of users to switch on headlamps.

European standards for day time running lamps for motorcycles have been developed. New motorcycles are fitted increasingly with headlights which come on automatically with ignition.

Research indicates that two lamps and lamps over 180mm diameter have greater influence than single or smaller lamps.

The use of daytime running lights by motorized two-wheelers has reduced visibility-related crashes in several countries by between 10% and 16%. In Europe, motorcyclists who use daytime running lights have a crash rate that is about 10% lower than that of motorcyclists who do not. In Austria, automatic DRL reduced the number of injured motorcyclists in daytime multiple crashes by about 16%. One estimate of the cost-benefit ratio of using running lights in daytime is put at around 1:5.4 for mopeds and 1:7.2 for motorcycles.

Anti-lock Braking Systems

The aggressive front wheel brake systems in use today are important to keep the enhanced driving performance in check. However, in the case of emergency braking, they can cause the front wheel to block and the driver to fall off the motorcycle. Anti-lock braking can prevent the front wheels of a motorcycle from locking and help to maintain stability. One prospective estimate suggests that ABS might reduce the number of crash victims by at least 10%. Typically, these systems are available on more expensive models of motorcycle.

As part of its commitment to the European Road Safety Charter Honda has pledged to increase the installation of advanced braking systems (Advanced braking systems are brake systems in which either an Anti-lock Brake System (ABS) and/or a Combined (or Linked) Brake System (CBS) are present) so that by 2007, the majority of its powered two wheeler models will be equipped (either as standard equipment or as optional equipment, depending on the model) with Honda's advanced braking systems.

Crash protection measures

Mandatory crash helmet use

Approximately 80% of motorcyclists killed on European roads sustained head impacts and in half of these cases, the head injury was the most serious. Motorcycle helmets aim protect against head injuries in the event of a crash and to reduce the severity of such injuries. Full face helmets provide better protection than open face helmets. See EEVC Motorcycle Safety Review. Helmets can reduce fatal injury by around 44%.

Table 2 Injury-reducing effects of helmets for moped-riders and motorcyclists Elvik and Vaa, 2004)

Only mandatory use legislation can achieve high levels of use and injury reduction. A meta-analysis of studies - mainly from the United States, where many laws on helmets were introduced in the period 1967 -1970 (and about half of which were repealed between 1976 and 1978) found that the compulsory helmet wearing reduced the number of injuries to moped riders and motorcyclists by 20 -30%. Analysis of the effects of repealing helmet wearing laws showed that withdrawing them resulted in 30% more deaths, a 5 -10% increase injuries to moped riders and motorcyclists. In Europe, an evaluation of helmet use and traumatic brain injury, before and after the introduction of legislation, in the region of Romagna, Italy, found that helmet use increased from an average of less than 20% in 1999 to over 96%in 2001, and was an effective measure for preventing traumatic brain injury at all age.

Economic evaluations of a mandatory helmet wearing law indicate that the use of helmets for moped riders and motorcyclists has a benefit-cost ratio of around 17 ( 6) (Norway), a result confirmed by American cost-benefit analyses.

Research has found that present helmets are too stiff and too resilient, with the maximum energy absorption of the liner occurring at high impact velocities where the probability of death is high. Helmet shells and liners should be less stiff in order to provide maximum energy absorption at lower, more prevalent, impact velocities where the benefit of a wearing a helmet can be more effectively realised. The COST 327 European Research Action on motorcycle helmets reported that improvements in helmet design could save up to 1,000 lives per year across the EU. A UN ECE regulation exists but has superseded the British Standard 6658 which included tests for rotation and the chin guard deemed necessary following in depth crash injury research.

Chest air bags

In head on collisions, the rider continues to move forward in a seated position and hits the opposing object at close to pre-impact velocity. These crashes often result in fatal or serious injury to the head and upper body of the motorcyclist.

While the provision of air bags on motorcycles is more complex than installation in cars, because the dynamics of a motorcycle crash are more difficult to predict, early crash tests with airbags on motorcycles (1973) indicated that an airbag system could be beneficial in frontal impacts. In the early 1990s tests were completed in the UK in which three different types of motorcycle were fitted with an airbag. The results showed that full restraint was not possible above a speed of 30 mile/h, though reducing speed and controlling rider trajectory could still be beneficial. Further work was carried out by the Transport Research Laboratory and Honda during the 1990s.

In 2004, Honda announced that it had developed the world's first production motorcycle airbag system to be made available in 2006 on new Gold Wing motorcycles. See Honda Motorcycle Airbag System. The airbag module, containing the airbag and inflator, is positioned in front of the rider. A unit in the airbag positioned to the right of the module analyses signals from the crash sensors to determine whether or not to inflate the airbag. Four crash sensors attached on both sides of the front fork detect changes in acceleration caused by frontal impacts.

Figure 9

Leg protection

Injuries to the legs of motorcyclists occur in approximately 80% of all crashes. In all collisions in which the motorcyclist is hit in the side by a car or other party, the forces involved impact the legs directly.

A large amount of research has been conducted in this area which shows that leg protectors could help reduce those injuries which result from direct crushing of the rider's leg against the side of the motorcycle during impact. Studies show different possibilities for optimising leg protection. Studies with leg protective airbags have also been carried out. Nairn estimated that the severity of leg injuries would be reduced in approximately 50% of the crashes which involved serious leg injury if leg protection were to be fitted. Further work in this area has been recommended to ensure that leg protection does not change rider trajectory to result in negative side effects.

Protective clothing

Many riders sustain soft tissue injuries from road impact, and suitable protective clothing systems have been developed. A European CEN standard now exists to promote higher levels of effectiveness in clothing (EN 13594 gloves; EN 13595-1 bis -4 jackets, trousers and combi-units; EN 13634 shoes). A drop-test is used to measure shock absorption. Special protector systems are used on the shoulders, elbows, arms and thorax, and special back protectors are used to protect the spine.

A review of the literature found that improved design and wider use of protective clothing could make a significant contribution to lessening the severity of motorcycle injuries (Elliot et al, 2003). Protective clothing can:

• Prevent most laceration and abrasion injuries that occur when a rider slides on the road surface after falling off.
• Prevent contamination of open fractures by road dirt.
• Reduce the severity of contusions and fractures, with the prevention of some fractures and joint damage.
• Reduce the severity (or prevention) of muscle stripping and degloving injuries, particularly to the lower leg and hands.
• Prevent crashes by maximising the conspicuity of the rider.
• Prevent crashes by maintaining the rider in good physiological and psychological condition by keeping the rider dry, warm, comfortable and alert.

The selection of single items of clothing and their combined use should be based on the following considerations:

• Clothing must be able to protect against, wet, cold and heat even when these occur for long periods.
• A set of clothing may be bought by a rider from different sources. It is therefore important that advice should be given on compatible items. For example there should not be a gap between boots and trousers.
• The outermost layer should always be of high conspicuity even in wet weather.
• Clothing should be designed to ensure that all tasks required of a motorcyclist are easily accomplished and in particular movement must not be restricted.