Has the helmet law improved safety?

Abstract

After the helmet law, the risk of accidents doubled, and the risk of death & serious injury for child cyclists in NSW, Australia, was 57% higher than what would have been expected without a helmet law.  

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The helmet law has been introduced on a belief that it could only improve safety.  The assumption was that, since helmets provide some protection, forcing everybody to wear a helmet can only improve safety.

Has it improved safety?  There has been surprisingly little comprehensive research to assess the effectiveness of the helmet law, or to compare cycling safety in Australia with the rest of the of the world.

A noticeable impact of the helmet law has been to reduce cycling.  Far more people stopped cycling rather than opted to wear a helmet.

drop_in_cycling-nsw_2

The main result of the helmet has been to reduce cycling

The helmet law was introduced in Australia at the same time as other road safety measures like a crackdown on speeding and drink driving.  A way to isolate the impact of the helmet law from these other safety measures is to compare cycling safety with pedestrian safety.

Some government funded studies like this one claim that the helmet law has been effective.  Such “studies” fail to take into account two important factors:

  1. There were 30 to 40% fewer cyclists.  The risk must be adjusted per km cycled or per cyclist.
  2. The helmet law was introduced at the same time as other road safety measures, like a crackdown on speeding and drink driving. Injuries declined significantly for pedestrians, who face a similar risk as cyclists, being hit by motorists. By adjusting for safety improvements observed with pedestrians, we can isolate the effect of external factors, so that we can better understand what can be genuinely attributed to helmets.

Those studies attribute all apparent safety improvements to helmets, failing to consider confounding factors.  After adjusting for those factors, the touted decline in head injuries vanishes.

An objective assessment of the effectiveness of the helmet laws needs to take into account the decline in cycling and the impact of other safety measures introduced at the same time.

Dr. Dorothy Robinson has done thorough research in this area.  In this article, she mentions that the helmet law has increased the risk of injury per cyclist.

mandatory bicycle helmet laws increase rather than decrease the likelihood of injuries to cyclists …

Having more cyclists on the road is far more important than having a helmet law, for many reasons …

[the] governments [which introduced the helmet laws] do not like to admit they’ve made mistakes”.

A short summary of Dr. Robinson’s work in this area can be found here:

More importantly, risks per cyclist seem to have increased, compared to what would have been expected  without the law, implying that helmet laws are counter-productive.  Possible explanations include risk  compensation, reduced ‘Safety in Numbers’ and that brain damage is predominantly due to rotational injury.

Cycling injuries has shown a similar trend as pedestrian injuries after the helmet law.  The large rise in helmet wearing does not seem to have made much difference.  Taking into account the decline in cycling by 30 to 40%, the risk of injury per cyclist increased.

A more detailed analysis can be found in this report (page 465).  After the helmet law, the risk of death and serious injuries for child cyclists increased by 21%, compared to a decrease by 21% for child pedestrians.

count_and_injuries_after_helmet_law

After the helmet law, the number of child cyclists decreased by more than cyclists death & serious injuries.  Pedestrians injuries decreased significantly, indicating general road safety improvements that would have benefited cyclists. The risk of death & serious injury for child cyclists increased significantly compared to what would have been expected without a helmet law.

From the graph above, it can be seen how a biased study can claim that the helmet law has improved safety, by focusing on the apparent decline in injuries, while ignoring that the number of cyclists declined even further, and ignoring general road safety improvements.  Most “studies” funded by the government, attempting to defend government policy, do that.  They mislead rather than inform.

This data indicates that the risk of death & serious injury for child cyclists in New South Wales (NSW) increased significantly (by more than 50%) compared to what would have been expected without a helmet law.  Explanations for the deterioration in safety include risk compensation and safety in numbers, resulting in an increase in accidents.

risk-compensation

Risk compensation is the tendency to take more risks when wearing safety equipment.
Lured by a false sense of safety, helmeted cyclists tend to have more accidents.
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A false sense of safety can induce people to take more risks, leading to more accidents and more injuries. This tendency is called risk compensation, a well-known safety factor as reported here:

“the law of unintended consequences is extraordinarily applicable when talking about safety innovations. Sometimes things intended to make us safer may not make any improvement at all to our overall safety”

Wearing a helmet can induce cyclists to take more risks, sometimes with serious consequences:

“the increased use of bike helmets may have had an unintended consequence: riders may feel an inflated sense of security and take more risks. …

The helmet he was wearing did not protect his neck; he was paralyzed from the neck down. …

”I definitely felt safe. I wouldn’t do something like that without a helmet.” ”

1989 study found that helmet wearers were 7 times more likely to have accidents. How can a flimsy piece of polystyrene compensate for 7 times more accidents?

Helmets accidents cycle

Risk compensation affects not only cyclists but also motorists who tend to be less careful around helmeted cyclists. As reported in a study published by the University of Bath in the UK:

“Bicyclists who wear protective helmets are more likely to be struck by passing vehicles”

Both the behaviour of the helmeted cyclist and surrounding motorists tends to increase the risk of accidents.

“Safety in numbers” is explained in a 2003 paper published in the Injury Prevention journal:

“the behavior of motorists controls the likelihood of collisions with people walking and bicycling. It appears that motorists adjust their behavior in the presence of people walking and bicycling …

A motorist is less likely to collide with a person walking and bicycling if more people walk or bicycle. Policies that increase the numbers of people walking and bicycling appear to be an effective route to improving the safety of people walking and bicycling.”

safety_in_numbers_6

A key factor for cycling safety is the number of cyclists.  This is called “safety in numbers”.
With fewer cyclists, cycling becomes more dangerous.
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This impact can easily be underestimated. Even under conservative assumptions of a 22% decline in cycling, the risk of accidents increases by 16%. This results in a net increase in cycling injuries despite an increase in helmet wearing. A 44% decline in cycling increases the risk of accidents by 41%. This cannot be compensated by a 9% in helmet wearing. The helmet law is likely to have increased the risk of death & serious injury by indirectly increasing the risk of accident.

Evidence of an increase in accidents can be seen in Table 2 on Page 465 of the report.  Hospital data reveals that, compared to what would have been expected without the helmet law, the risk of non-head injuries almost doubled, indicating that risk of accidents almost doubled.

risk_of_injury_after_helmet_law

Compared to what would have been expected without the helmet law, the risk of accident almost doubled.  The risk of death & serious injury increased by 57%, as helmets could not compensate for increased accidents.

This is similar to what was observed in a data set including children and adults, where the risk of injury more than tripled.

cycling_inury_rate_following_helmet_law_2

Cycling has become more dangerous after the helmet law. It would appear misguided to insist on reducing the risk of minor injuries when it increases the risk of serious injuries in other ways.

Australia has one of the worst cycling safety record among developed countries. The cyclist fatality rate is five times greater than in the Netherlands, while the serious injury rate is 22 TIMES greater. For urban cycling, the fatality rate per commuter cyclist is 27 times higher in Sydney, Australia than in Copenhagen, Denmark. This huge difference indicates an accident rate several orders of magnitude higher.

serious_injury_per_100m_km_cycled

New Zealand introduced a bicycle helmet law in 1994. A cycling safety perception survey reveals that most people believe that cycling has become more dangerous since the helmet law. Comparing cycling with ‘when I was at high school’ (before the helmet law), 83% report that cycling is more dangerous, while only 20% believe that cycling has become safer over the last 10 years (since 1994: introduction of helmet law).

In 1988, the largest ever cycling casualty study was published, involving more than eight million cases of injury and death to cyclists over 15 years in the US. It concluded:

“There is no evidence that hard shell helmets have reduced the head injury and fatality rates. The most surprising finding is that the bicycle-related fatality rate is positively and significantly correlated with increased helmet use.

Rodgers, G.B., Reducing bicycle accidents: a reevaluation of the impacts of the CPSC bicycle standard and helmet use, Journal of Products Liability, 11, pp. 307-317, 1988.

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2 Responses to “Has the helmet law improved safety?”

  1. Anthony says:

    Interesting

  2. Peter says:

    No wonder almost no other countries have followed Australia’s “lead” after more than 20 years. Reducing cycling while increasing the risk of accidents is not a great outcome. What a poor example Australia has set.

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