Randy Swart Takes Barnes to Task

BHSI's response to the NYT article on Bike Helmets and Risk Compensation

In Randy Swart's response to Barnes' article, he complains that, "We will be dealing with its myths for many years." This, ironically, is precisely the complaint of many cyclists and road safety advocates who feel that we have all been dealing, for almost two decades, with the results of a few poorly-designed studies from the mid to late 1980's. These studies (according to their critics) prematurely announced exaggerated levels of protection achievable through the use of cycle helmets.

The simplistic conclusion of these early researchers -- that putting styrofoam helmets on cyclists would ensure cyclist safety -- was (understandably) overwhelmingly popular with both highway authorities and motorists. It was also popular with some cyclists who liked such an easy (purchasable) way of feeling safe on the road. It was far easier to implement than any solution which would have required a deeper examination of the causes of road risk, of the complexity of individual risk taking behaviour, and of the gradual but inexorable displacement of non-motorized road users by the private automobile. It didn't seem to matter if some cyclists disagreed or objected: cyclists are a small minority in automobile-centred countries, and a minority with very little political clout. Those who resisted the helmet theory could easily be dismissed as cranks, sore losers, or compulsive risk-takers.

Thus the helmet promoters, essentially, "won" -- in several countries, the authorities enacted mandatory helmet laws for all ages; in even more localities, mandatory helmet laws for juveniles were enforced; official "road safety" programs started to focus their funded efforts solely on helmet promotion; and helmet sales increased dramatically along with usage rates. This social experiment has now been running for long enough that its results can be evaluated; Barnes' article seems like a good first step in this direction. We have now been dealing for many years with the results of the original hard-sell of helmets to authorities and the public: this seems like a good time to take an objective look at those results, and determine whether the original claims were closer to myth or reality.

Quite understandably, committed helmet promoters like Mr Swart would be very disappointed to admit that the strategy in which they have invested so much sincere passion and effort may not really be solving the problem. Contention and dispute are to be expected -- this has been a loaded topic, and a generator of Internet "flame wars," for over 20 years. However, Mr Swart goes further than mere disagreement when he attempts to dismiss Barnes' article as a mere "troll" (i.e. something written frivolously and captiously, with the sole intent of stirring up a fuss).

Barnes has raised serious issues which have engaged many people for many years, and I wish that Mr Swart (a fairly well-known representative of the pro-helmet point of view) would engage his opponent more seriously, rather than trying to dismiss the author and the article as frivolous, or accuse the newspaper of poor journalism, biased coverage, etc. Helmet contrarians, interestingly enough, found the article quite unsatisfactory in the opposite sense -- and this would seem to indicate that it was not strongly biased in either direction.

I found Swart's reply generally unconvincing, since it uncritically quotes statistics which have been repeatedly challenged (I would go so far as to say discredited) over the last 20 years of research. I will leave others to walk through one more iteration of the ritual debate over "the 98 percent figure" and so forth. In my view, the most unfortunate talking point in Swart's vehement reply to Barnes may be this:

"We do not believe that helmets give a false sense of security, any more than seat belts, air bags, smoke detectors, steel-toed boots or parachutes do. Anti lock brakes on cars are cited as a parallel by one of the experts, even though crashes related to them are generally due to drivers not realizing that they require a very different braking action in a panic stop."
This seems to me like going out very far on a very thin limb. It seems in fact to indicate an unfamiliarity with the literature of behavioural adaptation (aka risk compensation, aka risk homeostasis, etc.). Air bags and anti-lock brakes in particular have been the subject of several well-known papers on risk compensation. Here are some basic references from Wilde; while it's true that one can pick a bone or two with his most recent edition of _Target Risk_, in this case he is merely quoting fairly reputable sources:

Three economists at two universities in the State of Virginia compared the accident experience of passenger cars with and without airbags and came to the conclusion that "insurance industry-generated data reveal that injury claims increase following adoption of an air bag system" and that "Virginia State Police accident reports indicate that air-bag-equipped cars tend to be driven more aggressively and that aggressiveneess appears to offset the effect of the air bag for the driver and increase the risk of death to others."
[Wilde summarizes and quotes] Peterson, Hoffer, and Millner "Are drivers of air-bag-equipped cars more aggressive? a test of the offsetting behavior hypothesis" Journal of Law and Economics #38, 251-264 (1995)
With regard to ABS systems:
"The most interesting results include the finding that, with the use of ABS, driving speeds and pressure exerted on the brake pedal were higher when drivers knew they were driving with the ABS system turned on... drivers utilized the more sophisticated brakes for higher speeds and harder braking, not for greater safety."
[Wilde's summary of] Grant and Smiley, "Driver response to antilock brakes: a demonstration on behavioural adaptation" from Proceedings, Canadian Multidisciplinary Road Safety Conference VIII, June 14-16, Saskatchewan 1993
Similar results were obtained in Norway:
"Similarly, a 1996 study of 1384 different taxis travelling to the airport in Oslo, Norway, shhowed that cabs equipped with ABS followed the car in front significantly mjore closely than cabs without ABS."
[Wilde's summary of] Sagberg, Fosser, and Saetermo, "An investigation of behavioural adaptation to airbags and antilock brakes among taxi drivers" Accident Analysis and Prevention #29 pp 293-302 1997
And similar results were obtained in Germany:
"Among a total of 747 accidents incurred by the company's taxis during that period [three years], the involvement rate of the ABS vehicles was not lower, but slightly _higher_, although not significantly so in the statistical sense... drivers of cabs with ABS made sharper turns in curves, were less accurate in their lane-holding behaviour, proceeded at a shorter forward sight distance, made more poorly adjusted merging manoeuvres, and created more 'traffic conflicts'. ... Finally, as compared with the non-ABS cabs, the ABS cabs were driven faster at one of the four measuring points along the route. All these differences were significant... The Munich taxicab experiment attracted a great deal of attention, not only in the professional circles, but also in the popular press. Newspapers carried articles about it and Bavarian Television wanted to show the viewers what had happened. As the experiment had already been concluded, they decided to re-enact the experimental manipulation and the way the drivers had responded... The results of this experiment were also discussed by a group of international experts from the OECD." [see below]
Aschenbrenner and Biehl, "Improved safety through improved technical measures? empirical studies regarding risk compensation processes in relation to anti-lock braking systems." In Trimpop and Wilde, Challenges to Accident Prevention: The issue of risk compensation behaviour (Groningen, NL, Styx Publications, 1994)
These results were considered (along with others) by a major OECD task force on transportation safety, which concluded:
"An important conclusion of the Scientific Expert Group is that behavioural adaptation exists, and does have an effect on the safety benefits achieved through road safety programmes."
[original wording] OECD "Behavioural adaptations to changes in the road transport system" (Paris, OECD Road Transport Research 1990)
In the light of all these (and many more) publications, insurance industry findings and practises, clinical psychology studies on risk taking propensity and risk aversion, etc., it seems rash of Mr Swart to deny categorically the very existence of risk compensation or adaptive behaviour.

He could claim it is a smaller effect than the benefit of helmets; he could rightly claim that there is a difference of opinion among experts, or that the issue is controversial. But in choosing specifically air bags and ABS as strong illustrative examples for a complete dismissal of risk compensation -- when in fact they have been investigated in published studies with just the reverse finding -- he seems to be taking a precarious position.

De Clarke