Motorists drive closer to helmet-wearing cyclists reaffirms a paper published today by British psychologist Dr. Ian Walker and Australian statistician Dorothy Robinson. They reexamined Walker’s data from a much-cited 2007 study which additionally found that bare-headed women cyclists were afforded the greatest passing distances by motorists. Statisticians from the University of New South Wales in Australia had earlier rebutted Walker’s helmet findings. Today’s study from Walker and Robinson is, therefore, a rebuttal of this rebuttal.
Whether or not bicycle helmets offer whole-population safety benefits is a surprisingly fractious debate among academics – there is no settled science on the matter.
Dr. Walker’s 2007 study used a bike equipped with a camera and a distance measuring device. He recorded data from 2,500 drivers who passed him on the roads close to his workplace, the University of Bath. Half the time he wore a bicycle helmet and half the time he didn’t. The results showed motorists tended to pass him more closely when he rode wearing a helmet. Such “punishment passes” can also lead to collisions, collisions which can result in injury and death – and not to those guilty of the dangerous overtakes.
Walker suggested that drivers believe cyclists who wear helmets are more serious, experienced and predictable than those who ride without, and motorists, therefore, overtake them with less care. Drivers may also wrongly assume that cycle helmets – usually made from expanded-polystyrene – are forms of armor that will protect cyclists in any impact from motor vehicles. Cycle helmets are not designed for such collisions (they do not even protect against concussions.)
Jake Olivier and Scott Walter of the University of New South Wales took Walker’s original data and recrunched it, claiming in 2013 that “bicycle helmet wearing is not associated with close motor vehicle passing.”
Speaking to Forbes.com, Walker confided: “If somebody writes a paper saying your work is wrong, you look at it in some detail.”
Five years on and today’s paper is his response. He claims that Olivier and Walter were only able to disprove his study by redefining what was meant by the words “close” and “closer.”
“By analysing their data reworking it became clear the question they set themselves was slightly different to my original one,” said Walker in a telephone call.
“[Their study] all hung on their new definition of ‘close’, which they decided was to be 1 meter. The arbitrary nature of that definition is a key stumbling block of their paper.”
To challenge their conclusions, he enlisted the help of Robinson from Australia’s University of New England.
By using many different passing distances, and not just the single metric of the 2013 study, Walker and Robinson were able to double down on the findings of the 2007 paper.
“It's notable that the university research group [which wrote the 2013 paper and others] seem very interested in rebutting any suggestions that cycle helmets are not a panacea for safety,” remarked Walker.
In the new paper, Walker said he and his co-author “step back from micro debates about 1.5 meters versus 1 meter and start asking bigger questions about what would actually make cycling safe.”
This, he said, was “not having collisions in the first place rather than having collisions and trying to reduce their severity very slightly.”
He added: “Dorothy has done some very interesting research on compulsory helmet laws in Australia. Her [work] strongly suggests that when you look at the ‘before’ and ‘after’ of helmet laws you don’t see any benefits kicking in. If making people wear bicycle helmets was going to have a big effect on population safety you should see a big shift in injury rates at the time helmets became compulsory but her analysis shows that you don’t see that.”
He favors, instead, the removal-of-risk approach: “In terms of protecting cyclists from motor danger, we’re really going in the wrong direction if we’re focussing on [cycle] helmets that, at best, can only do something after a collision has happened.”
Walker believes the wearing of “personal protection equipment” (PPE) is the least effective option for dealing with potential hazards, with PPE “to be employed only once efforts to neutralize the hazard through elimination, substitution, engineering, and administrative controls have failed.” He prefers the Dutch approach: keep motorists and cyclists separate. Cycleways rather than helmets. (Dutch cyclists, by and large, do not wear helmets when cycling, and yet there is no epidemic of head injuries in the cycle-mad Netherlands.)
Other academics agree. Writing in 2012, Dr. Harry Rutter, an epidemiologist who specializes in physical activity, argued that “most of the risk of severe injury while cycling is not intrinsic to the activity – motorists impose it on cyclists.”
When he rides his bike Walker often wears a helmet. This was compulsory during a long-distance bicycle race he won recently. The North Cape 4000 was a non-stop 4,300-kilometer race from Italy to the top of Norway. Participants grabbed only the merest of rests, and even if helmet use hadn’t been required Walker said he would have worn one anyway due to the risk of falling from his bike thanks to sleep deprivation. (“My helmet was also more aerodynamic than my bare head, and so provided time benefits,” he pointed out.)
Despite being an occasional helmet wearer, Walker remains animated by his 2007 findings. “Wearing a [cycle] helmet might make a collision [with a motor vehicle] more likely in the first place,” he wrote at the time, a conclusion he says has now been confirmed.