Risk compensation is a theory which suggests that people typically adjust their behavior in response to the perceived level of risk, becoming more careful where they sense greater risk and less careful if they feel more protected.Although usually small in comparison to the fundamental benefits of safety interventions, it may result in a lower net benefit than expected.
By way of example, it has been observed that motorists drove faster when wearing seatbelts and closer to the vehicle in front when the vehicles were fitted with anti-lock brakes. There is also evidence that the risk compensation phenomenon could explain the failure of condom distribution programs to reverse HIV prevalence and that condoms may foster disinhibition, with people engaging in risky sex both with and without condoms.
By contrast, shared space is a highway design method which consciously aims to increase the level of perceived risk and uncertainty, thereby slowing traffic and reducing the number of and seriousness of injuries.
Risk compensation is related to the broader term behavioral adaptation which includes all behavior changes in response to safety measures, whether compensatory or not. However, since researchers are primarily interested in the compensatory or negative adaptive behavior the terms are sometimes used interchangeably.The more recent version emerged from road safety research after it was claimed that many interventions failed to achieve the expected level of benefits but has since been investigated in many other fields.
The reduction of predicted benefit from regulations that intend to increase safety is sometimes referred to as the Peltzman effect in recognition of Sam Peltzman, a professor of economics at the University of Chicago Booth School of Business, who published "The Effects of Automobile Safety Regulation" in the Journal of Political Economy in 1975 in which he controversially suggested that "offsets (due to risk compensation) are virtually complete, so that regulation has not decreased highway deaths". ( Adams 1879 ). A reanalysis of his original data found numerous errors and his model failed to predict fatality rates before regulation ( Robertson 1977 ). According to Peltzman, regulation was at best useless, at worst counterproductive. Peltzman found that the level of risk compensation in response to highway safety regulations was complete in original study. But "Peltzman’s theory does not predict the magnitude of risk compensatory behaviour." Substantial further empirical work has found that the effect exists in many contexts but generally offsets less than half of the direct effect. In the U.S., motor vehicle fatalities per population declined by more than half from the beginning of regulation in the 1960s through 2012. Vehicle safety standards accounted for most of the reduction augmented by seat belt use laws, changes in the minimum drinking age, and reductions in teen driving ( Robertson 2015 ).Peltzman claimed to originate this theory in the 1970s but it was used to oppose the requirement of safety equipment on trains in the Nineteenth Century
The Peltzman effect can also result in a redistributing effect where the consequences of risky behaviour are increasingly felt by innocent parties (see moral hazard). By way of example, if a risk-tolerant driver responds to driver-safety interventions, such as compulsory seat belts, crumple zones, ABS etc. by driving faster with less attention, then this can result in increases in injuries and deaths to pedestrians.
Risk homeostasis is a controversial hypothesis, initially proposed in 1982 by Gerald J. S. Wilde, a professor at Queen's University in Canada, which suggests that people maximise their benefit by comparing the expected costs and benefits of safer and riskier behaviour and which introduced the idea of the target level of risk.He proposed four constituents to a person's calculations relating to risk:
Wilde noted that when Sweden changed from driving on the left to driving on the right in 1967, this was followed by a marked reduction in the traffic fatality rate for 18 months after which the trend returned to its previous values. He suggested that drivers had responded to increased perceived danger by taking more care, only to revert to previous habits as they became accustomed to the new regime.A similar pattern was seen following Iceland's switch from left- to right-hand driving.
In a Munich study, part of a fleet of taxicabs were equipped with anti-lock brakes (ABS), while the remainder had conventional brake systems. In other respects, the two types of cars were identical. The crash rates, studied over three years, were a little higher for the cabs with ABS, [ citation needed ]Wilde concluded that drivers of ABS-equipped cabs took more risks, assuming that ABS would take care of them; non-ABS drivers were said to drive more carefully since they could not rely on ABS in a dangerous situation.
The idea of risk homeostasis is disputed. One author claimed that it received "little support",another suggested that it "commands about as much credence as the flat earth hypothesis", a third noted that the proposal did create considerable media attention: "What set the debate alight, rather like petrol on flames, was the proposition in 1982 that road users did not just adapt to perceptions of changing risk through compensatory behaviors, but that the process was a homeostatic one, producing overall equilibrium in safety-related outcomes". Others claimed that road fatality statistics, which have fallen considerably since the introduction of safety measures, do not support the theory.
Anti-lock braking systems are designed to increase vehicle safety by allowing the vehicle to steer whilst braking
A number of studies show that drivers of vehicles with ABS tend to drive faster, follow closer and brake later, accounting for the failure of ABS to result in any measurable improvement in road safety. The studies were performed in Canada, Denmark, and Germany.A study led by Fred Mannering, a professor of civil engineering at the University of South Florida supports risk compensation, terming it the "offset hypothesis". A study of crashes involving taxicabs in Munich of which half had been equipped with anti-lock brakes noted that crash rate was substantially the same for both types of cab, and concluded this was due to drivers of ABS-equipped cabs taking more risks.
However, the Insurance Institute for Highway Safety released a study in 2010 that found motorcycles with ABS 37% less likely to be involved in a fatal crash than models without ABS.A 2004 study found that ABS reduced the risk of multiple vehicle crashes by 18 percent, but had increased the risk of run-off-road crashes by 35 percent.
A 1994 research study of people who both wore and habitually did not wear seatbelts concluded that drivers were found to drive faster and less carefully when belted.
Several important driving behaviors were observed on the road before and after the belt use law was enforced in Newfoundland, and in Nova Scotia during the same period without a law. Belt use increased from 16 percent to 77 percent in Newfoundland and remained virtually unchanged in Nova Scotia. Four driver behaviors (speed, stopping at intersections when the control light was amber, turning left in front of oncoming traffic, and gaps in following distance) were measured at various sites before and after the law. Changes in these behaviors in Newfoundland were similar to those in Nova Scotia, except that drivers in Newfoundland drove slower on expressways after the law, contrary to the risk compensation theory ( Lund & Zador 1984 ).
In Britain in 1981 at a time when the government was considering the introduction of seat belt legislation, John Adams of University College London, suggested that there was no convincing evidence of a correlation between the seat-belt legislation and reductions injuries and fatalities based on a comparison between states with and without seat belt laws. He also suggested that some injuries were displaced from car drivers to pedestrians and other road users.The "Isles Report" echoed these concerns. Adams subsequently argued that the reduction in fatalities that followed the introduction of legislation could not be attributed with confidence to seat-belt use due to the simultaneous introduction of breath testing for driving under the influence of alcohol.
However, a 2007 study based on data from the Fatality Analysis Reporting System (FARS) of the National Highway Traffic Safety Administration concluded that between 1985 and 2002 there were "significant reductions in fatality rates for occupants and motorcyclists after the implementation of belt use laws", and that "seatbelt use rate is significantly related to lower fatality rates for the total, pedestrian, and all non-occupant models even when controlling for the presence of other state traffic safety policies and a variety of demographic factors".A comprehensive 2003 US study also did "not find any evidence that higher seat belt usage has a significant effect on driving behavior." Their results showed that "overall, mandatory seat belt laws unambiguously reduce traffic fatalities."
In Sweden, following the change from driving on the left to driving on the right in 1967 there was a drop in crashes and fatalities, which was linked to the increased apparent risk. The number of motor insurance claims went down by 40%, returning to normal over the next six weeks.Fatality levels took two years to return to normal.
The control of traffic speeds using effectively enforced speed limits and other traffic calming methods plays an important role in the reduction of road traffic casualties;speed limit changes alone without accompanying enforcement or traffic calming measures will not.
A 1994 study conducted to test the risk homeostasis theory, using a driving simulator, found that increasing posted speed limits and a reduction of speeding fines had significantly increased driving speed but resulted in no change in the accident frequency. It also showed that increased accident cost caused large and significant reductions in accident frequency but no change in speed choice. The results suggest that regulation of specific risky behaviors such as speed choice may have little influence on accident rates.
Shared space is an approach to the design of roads, where risk compensation is consciously used to increase the level of uncertainty for drivers and other road users by removing traditional demarcations between vehicle traffic by removing curbs, road surface markings, and traffic signs. The approach has been found to result in lower vehicle speeds and fewer road casualties.
Campaigns and legislation to encourage the wearing of cycle helmets have not been shown to reduce significant head injuries,and "there is evidence to suggest that some cyclists ride less cautiously when helmeted because they feel more protected". In one experimental study, adults accustomed to wearing helmets cycled more slowly without a helmet, but no difference in helmeted and unhelmeted cycling speed was found for cyclists who do not usually wear helmets. A Spanish study of traffic accidents between 1990 and 1999 found no strong evidence of risk compensation in helmet wearers but concluded that "this possibility cannot be ruled out".
Motorists may also alter their behavior toward helmeted cyclists. One study by Walker in England found that 2,500 vehicles passed a helmeted cyclist with measurably less clearance (8.5 cm) than that given to the same cyclist unhelmeted (out of an average total passing distance of 1.2 to 1.3 metres). The significance of these differences has been re-analysed by Olivier, who argued that the effect on safety was not significant since the passing distances were over 1 metre, and again by Walker, who disagreed with Olivier's conclusion.
In 1988, Rodgers re-analysed data which supposedly showed helmets to be effective and found both data errors and methodological weaknesses. He concluded that in fact the data showed "bicycle-related fatalities are positively and significantly associated with increased helmet use" and mentioned risk compensation as one possible explanation of this association.
Recent studies indicate that skiers wearing helmets go faster on average than non-helmeted skiers,and that overall risk index is higher in helmeted skiers than non-helmeted skiers. Moreover, while helmets may help prevent minor head injuries, increased usage of helmets has not reduced the overall fatality rate.
Other recent studies have concluded that helmet use is not associated with riskier behavior among skiers and snowboarders, and that helmet usage reduces the risk and severity of head injuries.
'Booth's rule #2', often attributed to skydiving pioneer Bill Booth, states, "the safer skydiving gear becomes, the more chances skydivers will take, in order to keep the fatality rate constant".Even though skydiving equipment has made huge leaps forward in terms of reliability, including the introduction of safety devices such as AADs, the fatality rate has stayed roughly constant when adjusted for the increasing number of participants. This can largely be attributed to an increase in the popularity of high performance canopies, which fly much faster than traditional parachutes. A greater number of landing fatalities in recent years has been attributed to high speed maneuvers close to the ground.
Experimental studies have suggested that children who wear protective equipment are likely to take more risks.
Evidence on risk compensation associated with HIV prevention interventions is mixed. Harvard researcher Edward C. Green argued that the risk compensation phenomenon could explain the failure of condom distribution programs to reverse HIV prevalence, providing a detailed explanations of his views in an op-ed article for The Washington Postand an extended interview with the BBC. A 2007 article in the Lancet suggested that "condoms seem to foster disinhibition, in which people engage in risky sex either with condoms or with the intention of using condoms". Another report compared risk behaviour of men based on whether they were circumcised. A 2015 study showed that adolescents with safe-sex beliefs (adolescents who believe that sex with condoms is 100% safe) have an earlier sexual initiation.
While pre-exposure prophylaxis (PrEP) with anti-HIV drugs appears to be extremely successful in suppressing the spread of HIV infection, there is some evidence that the reduction in HIV risk has led to some people taking more sexual risks; specifically, reduced use of condoms in anal sex,raising risks of spreading sexually transmitted diseases other than HIV.
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A seat belt is a vehicle safety device designed to secure the driver or a passenger of a vehicle against harmful movement that may result during a collision or a sudden stop. A seat belt reduces the likelihood of death or serious injury in a traffic collision by reducing the force of secondary impacts with interior strike hazards, by keeping occupants positioned correctly for maximum effectiveness of the airbag and by preventing occupants being ejected from the vehicle in a crash or if the vehicle rolls over.
Automotive safety is the study and practice of design, construction, equipment and regulation to minimize the occurrence and consequences of traffic collisions involving motor vehicles. Road traffic safety more broadly includes roadway design.
Road traffic safety refers to the methods and measures used to prevent road users from being killed or seriously injured. Typical road users include pedestrians, cyclists, motorists, vehicle passengers, horse riders, and passengers of on-road public transport.
Traffic psychology is a discipline of psychology that studies the relationship between psychological processes and the behavior of road users. In general, traffic psychology aims to apply theoretical aspects of psychology in order to improve traffic mobility by helping to develop and apply crash countermeasures, as well as by guiding desired behaviors through education and the motivation of road users.
A bicycle helmet is designed to attenuate impacts to the head of a cyclist in falls while minimizing side effects such as interference with peripheral vision. There is ongoing scientific research into the degree of protection offered by bicycle helmets in the event of an accident, and the effects of helmet wearing on cyclist and motor vehicle driver behaviour.
Seat belt legislation requires the fitting of seat belts to motor vehicles and the wearing of seat belts by motor vehicle occupants to be mandatory. Laws requiring the fitting of seat belts to cars have in some cases been followed by laws mandating their use, with the effect that thousands of deaths on the road have been prevented. Different laws apply in different countries to the wearing of seat belts.
The National Traffic and Motor Vehicle Safety Act was enacted in the United States in 1966 to empower the federal government to set and administer new safety standards for motor vehicles and road traffic safety. The Act was the first law to establish mandatory federal safety standards for motor vehicles. The Act created the National Highway Safety Bureau. The Act was one of a few initiatives by the government in response to an increasing number of cars and associated fatalities and injuries on the road following a period when the number of people killed on the road had increased 6-fold and the number of vehicles was up 11-fold since 1925.
Road toll is the term used in New Zealand and Australia for the number of deaths caused annually by road accidents.
Motorcycle safety concerns many aspects of vehicle and equipment design as well as operator skill and training that are unique to motorcycle riding.
Bicycle safety is the use of road traffic safety practices to reduce risk associated with cycling. Risk can be defined as the number of incidents occurring for a given amount of cycling. In many countries both the number of incidents and the amount of cycling are not well known. Non-fatal accidents often go unreported and bicycle use is only occasionally monitored. Some of this subject matter is hotly debated: for example, the discussions as to whether bicycle helmets or cyclepaths really improve safety. The merits of obeying the rules of the road including the use of bicycle lighting at night are less controversial.
Smeed's Law, named after R. J. Smeed, who first proposed the relationship in 1949, is a purported empirical rule relating traffic fatalities to traffic congestion as measured by the proxy of motor vehicle registrations and country population. The law proposes that increasing traffic volume leads to an increase in fatalities per capita, but a decrease in fatalities per vehicle.
Transportation safety in the United States encompasses safety of transportation in the United States, including automobile accidents, airplane crashes, rail crashes, and other mass transit incidents, although the most fatalities are generated by road accidents.
A ski helmet is a helmet specifically designed and constructed for winter sports. Use was rare until about 2000, but by about 2010 the great majority of skiers and snowboarders in the US and Europe wear helmets. Helmets are available in many styles, and typically consist of a hard plastic/resin shell with inner padding. Modern ski helmets may include many additional features such as vents, earmuffs, headphones, goggle mounts, and camera mounts.
A motorized scooter is a powered stand-up scooter using a small utility internal combustion engine or, more commonly, an electric motor. Classified as a form of micro-mobility, these scooters are generally designed with a large deck in the center on which the rider stands. The first production scooter, the "Sport", was released by Go-Ped in 1985.
Injury prevention is an effort to prevent or reduce the severity of bodily injuries caused by external mechanisms, such as accidents, before they occur. Injury prevention is a component of safety and public health, and its goal is to improve the health of the population by preventing injuries and hence improving quality of life. Among laypersons, the term "accidental injury" is often used. However, "accidental" implies the causes of injuries are random in nature. Researchers use the term "unintentional injury" to refer to injuries that are nonvolitional but preventable. Within the field of public health, efforts are also made to prevent or reduce "intentional injury." Data from the U.S. Centers for Disease Control, for example, show unintentional injuries are the leading cause of death from early childhood until middle adulthood. During these years, unintentional injuries account for more deaths than the next nine leading causes of death combined.
A traffic collision, also called a motor vehicle collision (MVC) among other terms, occurs when a vehicle collides with another vehicle, pedestrian, animal, road debris, or other stationary obstruction, such as a tree, pole or building. Traffic collisions often result in injury, disability, death, and property damage as well as financial costs to both society and the individuals involved.
Distracted driving refers to the act of driving while engaging in other activities which distract the driver's attention away from the road. Distractions are shown to compromise the safety of the driver, passengers, pedestrians, and people in other vehicles.
Luchemos por la Vida is a nonprofit organization whose purpose is to help prevent traffic accidents in Argentina. It promotes road traffic safety and focuses its efforts in contributing to safe behavior in the traffic system. The organization does not receive financial support from government agencies and is mainly held by the effort of volunteers, help from private firms, and services provided to the community. In 2010 there were 21 deaths per day in Argentina, more than 100,000 injured people, and severe material losses due to traffic accidents.
People who are driving as part of their work duties are an important road user category. First, workers themselves are at risk of road traffic injury. Contributing factors include fatigue and long work hours, delivery pressures, distractions from mobile phones and other devices, lack of training to operate the assigned vehicle, vehicle defects, use of prescription and non-prescription medications, medical conditions, and poor journey planning. Death, disability, or injury of a family wage earner due to road traffic injury, in addition to causing emotional pain and suffering, creates economic hardship for the injured worker and family members that may persist well beyond the event itself.
Rebecca Q. Ivers is an Australian academic known for her work in injury prevention research.
"The Peltzman (1975) effect predicts that when automobile safety regulations are made mandatory, at least some of their benefits will be offset by changes in the behavior of drivers
"In general, safety regulation did decrease the probability of death for drivers, but this is offset by involving themselves in a riskier behavior, which reassigns the change of deaths from vehicle occupants to pedestrians
Over a period of 36 months they observed part of a taxi fleet in Munich, Germany. Half of the observed vehicles were equipped with an anti-lock braking system (ABS)... The overall accident rate showed a slight increase for ABS taxis, but no significant differences between cars with the superior brake-system (ABS) versus cars without the system
risk homeostasis theory should be rejected because there is no convincing evidence supporting it and much evidence refuting it
On the day of the change, only 150 minor accidents were reported. Traffic accidents over the next few months went down. ... By 1969, however, accidents were back at normal levels
In high-income countries, an established set of interventions have contributed to significant reductions in the incidence and impact of road traffic injuries. These include the enforcement of legislation to control speed and alcohol consumption, mandating the use of seat-belts and crash helmets, and the safer design and use of roads and vehicles.
Contrary to popular belief, local speed limits should only be used if 85 out of 100 vehicles are already travelling at the speed it is wished to impose. Experience shows the speeds of these 85 vehicles are likely to influence the speeds of the other 15. This makes the speed limit largely self-enforcing and consequently makes for a manageable enforcement task
A recognition of ‘risk compensation effect’ prompts a fresh understanding of the adverse effects of measures such as traffic signals, signs, pedestrian guard rails and barriers on safety, and of their tendency to discourage informal physical activity. It may seem perverse to argue that well being can be improved through making spaces feel riskier, but that is the firm conclusion from both research, and from empirical studies
there is evidence to suggest that some cyclists ride less cautiously when helmeted because they feel more protected:...
although the findings do not support the existence of a strong risk compensation mechanism among helmeted cyclists, this possibility cannot be ruled out
The average speed for helmet users of 45.8 km/h (28.4 mph) was significantly higher than those not using a helmet at 41.0 km/h (25.4 mph)
The main findings of this study indicate that the overall Risk Index is higher in helmeted skiers than non-helmeted skiers. The population that contributes the most to the overall Risk Index value is male helmet wearers, signifying that male helmet wearers take more risks while skiing than others
This paper presents results that suggest that while helmets may be effective at preventing minor injuries, they have not been shown to reduce the overall incidence of fatality in skiing and snowboarding even though as many as 40% of the population at risk are currently using helmets
No evidence of risk compensation among helmet wearers was found
his finding is in alignment with risk compensation theory because it predicts that, essentially, skydivers will compensate for any new safety mechanism and consequently perform more dangerous types of jumping
The biggest opportunity for improvement in safety remains the selection and operation of main parachutes.
It appears that most of the incidents happened under small (the average reported size was 107 square feet), highly loaded canopies.