Archive for February 2010

What seat belt usage can teach us about motorcycle safety

February 28, 2010

As we’ve been told again and again, far more drivers wear seat belts than riders wear helmets. The National Occupant Protection Use Survey (NOPUS) estimates seat belt use at 83 percent in 2008 while helmet use at 67 percent in 2009. Statistics like that increase the perception motorcyclists don’t care much about personal safety. But seat belt history offers some insight into helmet use—and a different look helmet use history might change our perception about motorcyclists’ choice:

Manufacturers get the first mandate Seat belts were invented in the mid 1890s just as automobiles hit American streets, but it wasn’t until 1949 that Volvo and Nash first put seat belts in cars.[i] Few other manufacturers followed suit though and few people wore them.

State legislators, convinced of seat belt efficacy first demanded manufacturers put them in cars. By 1964 only half the states had the first seat belt laws—but that’s all it took; a year later all car manufacturers offered seat belts as standard equipment in every state. In 1972 the National Highway Safety Foundation (NHTSA) made it a federal requirement. But usage was extremely low—less than 11 percent.

Education fails Before and during this, though, a huge marketing effort (including the famous Buckle Up For Safety commercials) and an enormous public relations/media campaign to tout seat belt use was flooding the nation. And arguments raged about whether seat belts really were safe or more dangerous, which also happened with helmets.

More regulation In 1974 NHTSA required a buzzer/light reminder system or ignition locks to make it harder not to use seat belts. Ignition locks were more effective than the annoying sound/light that is still with us today. One study with a small number of drivers  found that usage rose to 67 percent but decreased over time as many owners disconnected the system or left them belted to circumvent the light/buzzer or lock.[ii] Studies using rental cars found that there was an insignificant difference in use between cars with or without the warning system.

Legislation not education Seat belts in cars and positive publicity was ineffective: usage was in the low teens through the 1970s. Iow, the public responded to seat belts as we’ve been led to believe riders responded to helmets.

It was only when mandatory seat belt laws were passed that use began to rise by 17-26 percent.[iii] California is a prime example: Before the mandatory seat belt law was passed in 1986 use was 26 percent. After the law it rose to 45 percent and crept up to 73 percent by 1993. After a primary enforcement law (meaning law enforcement could stop a driver solely for seat belt use) was passed in 1993 it rose to 83 percent and to 91 percent by 2002.[iv] Even so, by 2002, national usage was only 75 percent (and has since risen to 83 percent).

Negatives drive seat belt use And even recent studies find it’s only that high because of a combination of factors: use is higher in a primary enforcement states than in secondary enforcement state (where they have to have another reason to stop you). Use is higher among those who have a higher fear of getting a ticket than those who don’t think they at risk of a traffic stop. It’s higher when the ticket has a higher financial penalty. And studies have found that family and friends’ seat belt behavior matter and their pressure to buckle up matters and a general public attitude matter in influencing a driver’s behavior.

Otoh, programs educating drivers as to the risk and nature of injuries, offering incentives or raising fear of injuries weren’t very effective and had high recidivism. Once seat belt use becomes habitual, though, it tends to be self-maintaining.

Iow it’s the negative that drives seat belt usage until habit takes over and the decision is mindless. This attitude is so entrenched that the Committee for the Safety Belt Technology Study for the Transportation Research Board of the National Academies state that those who always wear belts, “… simply follow rules they have developed on the basis of experience, rather than continuously comparing risks against benefits in deciding whether to buckle up.”[v]

Part-time belt users gave these reasons for not wearing a belt included: driving a short distance (59 percent), forgetting to buckle up (53 percent); being in a rush (41 percent); and discomfort from the seat belt (33 percent). These are also reasons that some riders give for not wearing a helmet.

Non-users were by far the smallest percentage of the survey and gave some of the same reasons—laziness, short distances, forgetting, low speeds, short distances but also, “Many hard-core nonusers object to being forced to buckle up, believing that belt use should be a matter of personal choice.” This reason is the same argument anti-helmet law activists give for resisting helmet laws.[vi] Iow, we’re not so different than drivers when it comes to not wearing safety gear.

More of the same only tougher However the safety community is convinced that even habit is not enough; the Committee stated, “Strong enforcement is a necessary component of effective seat belt use laws. Motorists must be convinced that violators will be ticketed and nontrivial penalties exacted.”

The Prevention Institute article referred to a report published in 2000, in which  Transportation Department Inspector General Kenneth Mead stated, “Unless additional states enact and enforce primary laws, which are the most effective means of increasing seatbelt use, we see no credible basis to forecast increases in excess of the recent trend,” Mead stated in the report.

Iow, when it comes to helmets and belts traffic safety experts reject education as an effective tool when it comes to wearing safety equipment. Ever-tougher legislation is seen as the only way to force compliance.

Riders, though, don’t behave as drivers However for much of the past 30-some years, helmet use has been higher than seat belt use in states that don’t have helmet laws but do have seat belt ones. And helmet use in universal helmet law states has been higher than seat belt use in those same states before seat belt laws were passed.

Once again, we look at California: According to the Highway Loss Data Institute unit of the Insurance Institute of Highway Safety (IIHS), helmet use before the universal law was passed was 50 percent. Iow, it was already 24 percent higher than seat belt use was before the mandatory seat belt law was passed.

Immediately after California instituted a universal helmet law in 1992, use surged to 99 percent.[vii] In comparison, it took 16 years and a harsh primary enforcement law to achieve slightly less when it came to drivers.

While it’s true that helmet compliance is more obvious than shoulder/lap belt use,[viii] voluntary helmet use was already almost twice as high when the law was passed as voluntary seat belt use was before the seat belt law was passed. And driver compliance only achieved rider compliance after a strict primary enforcement law was instituted.

This is a significant and positive safety difference between drivers and riders that has been unobserved and unstudied.

But it is seat belts we’re talking about and they are provided in every car sold and  require little effort or discomfort to use and have overwhelming social approval attached to their use.

Otoh, even the lightest helmet is a distinct weight on the head, it’s hot to wear at times and the snug fit that’s required for effectiveness is uncomfortable for many. It can catch the wind causing neck strain and some feel that it obstructs their vision. And unlike seatbelts, a helmet must be replaced if it comes in violent contact with a hard surface. To top it off,[ix] even cheap ones are expensive and require additional  effort (compared to seatbelts) to obtain.

Riders’ performance actually better Despite all that, nationally, helmet use is still 67 percent even though only 20 states have universal helmet laws while seatbelt use is finally 83 percent 45 years after seatbelts were standard equipment in cars sold in the USA—even though 49 states have a mandatory seatbelt laws. And that’s a profound safety difference between drivers and riders that has been unobserved, unstudied and unappreciated.

While traffic experts bemoan the low rate of helmet use an equally valid case could be made for the high use of helmets in states without mandatory laws and in states prior to the passage of universal helmet laws. Considering the history of seat belt use, it’s rather extraordinary that so many riders choose on their own to purchase expensive, heavy and uncomfortable helmets and wear them when they aren’t required by law or receive any immediate benefit or incentive for doing so.

In fact, it suggests that riders who choose to wear helmets without a mandate are the opposite of extraordinary risk-takers. Instead it suggests that they are more aware of the risks inherent in motorcycling, believe that their odds of crashing are higher and take steps to mitigate harm.

Iow, it suggests that a significant proportion of motorcyclists take more personal responsibility for their own safety than drivers do.

And that’s a very different view of motorcyclists.


[i] Coincidentally, 1949 was the year Smeed published his “law”.

[ii] Buckling Up: Technologies to Increase Seat Belt Use — Special Report 278. Transportation Research Board (TRB). 2004.

[iii] Curtisa, Kevin M. and Scott W. Rodia and Maria Grau Sepulveda. The lack of an adult seat belt law in New Hampshire: Live free and die? Accident Analysis & Prevention, Volume 39, Issue 2, March 2007, Pages 380-383.

[iv] Gantz, Toni and Gretchen Henkle. Seatbelts: Current Issues. Prevention Institute. October 2002. http://ww.preventioninstitute.org/traffic_seatbelt.html. Highway Loss Data Institute, Insurance Institute of Highway Safety. Q&As: Motorcycle helmet use laws. January 2009. http://www.iihs.org/research/qanda/helmet_use.html.

[v] Committee for the Safety Belt Technology Study. Buckling Up: Technologies to Increase Seat Belt Use, Special Report 278. Transportation Research Board. 2004. http://www.nap.edu/openbook.php?record_id=10832&page=R1

[vi] It would be interesting if someone did a study to find out if those who didn’t wear helmets also didn’t wear seat belts.

[vii] Highway Loss Data Institute, Insurance Institute of Highway Safety. Q&As: Motorcycle helmet use laws. January 2009. http://www.iihs.org/research/qanda/helmet_use.html.

[viii] Though whether the helmet is DOT-certified is not as easy to determine.

[ix] All plays on words in the article are intentional.

Smeed’s Law and motorcycle fatalities

February 25, 2010

We’ve looked at the various pieces of the motorcycle safety puzzle and found that they all—without exception—have failed to bring the death toll down but as more riders practice them the death and injury toll goes up.

It’s time, then to explore other things that might affect the crash rate of motorcycles in America. Some of these readers have referred to—and we’ll look at them more closely. Some of them may seem quite far-fetched and some might be rather offensive. Yet, since the usual answers haven’t solved the puzzle, it’s appropriate to explore other factors—no matter how unpalatable—in case they may in part or in concert led to safer roads for riders.

We start with R.J. Smeed’s “Law” which was first published in 1949. It states that as the number of automobiles in a country increase so do fatalities in a predictable way: the number of deaths equals .0003 times the two-thirds power of the number of people times the one-third power of the number of cars.[i] After that point, road fatalities begin to fall off and then level off at a much lower point.

Despite safer cars, Smeed’s Law is still basically true in all developing countries. For example, it held true in the USA until about 1966—and his formula for the decline of traffic fatalities is very close to what has actually happened.

His friend, the eminent physicist Freeman John Dyson, wrote, “It is remarkable that the number of deaths does not depend strongly on the size of the country, the quality of the roads, the rules and regulations governing traffic, or the safety equipment installed in cars. Smeed interpreted his law as a law of human nature. The number of deaths is determined mainly by psychological factors that are independent of material circumstances. People will drive recklessly until the number of deaths reaches the maximum they can tolerate. When the number exceeds that limit, they drive more carefully. Smeed’s Law merely defines the number of deaths that we find psychologically tolerable.”[ii]

Of course, in 1965, Ralph Nader’s book, Unsafe At Any Speed, was published which both captured the general public’s growing frustration with traffic fatalities and exacerbated that frustration. From the mid-Sixties on there was a massive push for safer design, safer roads and safer crashing. Iow, Smeed was right about the linkage but assumed it would take more cars and deaths to get to the point we could no longer psychologically tolerate the death toll.

It’s true that motorcycles can’t be made as objectively safe (crush zones, front and side air bags, etc.) as cars—but then that’s true for bicyclists and pedestrians as well and their death rates have dropped in the past ten years while motorcyclist fatalities rose—and rose and rose outpacing registrations.

When it comes to automobiles and perhaps bicycles[iii], there’s not just a correlation but some kind of subconscious process at work that first allows the death toll to rise and then, eventually, lowers it.

But the key here is that drivers keep driving—they just drive safer.

The question is: does Smeed’s Law work for motorcycle registrations and rider deaths?  I’ll leave it to anyone who’s better at math than I to do the math but I do wonder: How can we as riders still “psychologically tolerate” the soaring death toll?

But here’s this—even if it does, it’s a little different when it comes to motorcycles:   The past 11 years is not the first surge in motorcycle registrations and fatalities in the USA. The most recent registration surge ended in the early 1980s and fatalities topped out in 1981. The death toll began dropping and bottomed out in 1997—even though registrations had begun to increase a few years earlier.

While 29 states either dropped or adjusted universal helmet laws during the 1970s while fatalities were rising, the laws weren’t reinstated yet fatalities dropped. From 1973-2001, 1.6 million were trained and all states began to require motorcycle licensing—and most were trained as fatalities were falling.

But the death toll did drop beginning in 1982—and so did registrations and then registrations started to go up in the early 1990s—and fatalities followed suit in 1998.

However since 2002, the Motorcycle Safety Foundation claims over 2 million have been trained—and yet fatalities have exceeded the height of the late 1970s-1981 surge in rider deaths.

Today, EMS response time is better than it ever has been, medical procedures are more effective and traffic system design has concentrated on safer roads and intersections. While this has brought about reductions in auto, bicycle and pedestrian deaths, some of that loss was simply transferred over to motorcyclist deaths.

Iow, just as with automobiles, Dyson’s words could be applied to motorcycles. It appears “the number of deaths does not depend strongly on the size of the country, the quality of the roads, the rules and regulations governing traffic, or the safety equipment.”

In this way, Smeed’s Law might be true but in a different way than with cars. When it comes to autos, people are sickened by the death rate and demand change as a nation of drivers—but they keep on driving and registrations keep on going up.

But motorcycling doesn’t behave the same way: in the past three cycles, registrations peaked before fatalities did—but unlike Smeed’s Law predicted, registrations did fall off.

Iow, while drivers either behave more safely or there are changes to design, roads or safety measures are brought to bear, this doesn’t happen with riders—yet the fatality rate still drops. But so does registrations.

It could be that individual riders no longer believe that riding is safe for them and give up motorcycling—and thus increased motorcycle “safety” is really attrition. Which doesn’t make motorcycling safer at all.


[i] Smeed, R. J. Some Statistical Aspects of Road Safety Research. Journal of the Royal Statistical Society. Series A (General), Vol. 112, No. 1 (1949), pp. 1-34.

[ii] Dyson, Freeman. “Part II: A Failure of Intelligence” Technology Review

http://www.technologyreview.com/Infotech/17847/page5/

[iii] Hakamies-Blomqvist, Liisa and Mats Wiklund, Per Henriksson. Predicting older drivers’ accident involvement – Smeed’s law revisited. Accident Analysis and Prevention 37 (2005) 675–680.

Louisiana injuries and motorcycle registrations

February 17, 2010

Motorcycle registrations v. motorcycle injuries

Now let’s compare motorcycle registration to all unhelmeted injuries. As we know, the Preusser Research Group, examining the effects of the repeal on behalf of the National Highway Traffic Safety Administration (NHTSA), claimed reliable data was not available and then dismissed the need to factor in registrations; “Further analysis suggests that regardless of this trend, the lack of a universal helmet requirement leads to increased motorcycle fatalities well beyond what might be expected from an increase in registrations.” The report goes on to say that, “This increase in helmet use after the reinstatement of the universal helmet law by crash-involved riders was associated with a significantly lower proportion of fatalities, severe injuries, and moderate injuries during the post-reinstatement period compared to the pre-law period. The analyses indicated that there were also fewer severe and fatal crashes following the law change.”

So we gave Preusser the benefit of the doubt and argued it that way and still found serious flaws in the group’s analysis.[i] Also, anti-helmet law advocates often argue that helmet laws cause registrations to go down and use that to argue that helmet laws are bad for tourism (as well as for small businesses such as dealerships, etc.). So let’s look at both assumptions and see how they measure up:

As DataDan already pointed out in terms of fatalities—the MV-1 tables are easily access through the Federal Highway Administration website:[ii]

The data does support the helmet story—injuries rose above the contribution of motorcycle registrations. Had Preusser included the motorcycle data—including the 2004, it would’ve confirmed their interpretation that unhelmeted use leads to more fatalities. But the story doesn’t stop there:

Once the helmet law was reinstated, helmeted fatalities rose fast and in three out of four years—and almost did in the fourth year. Iow, there’s very little difference between unhelmeted and helmeted injuries in comparison to registration—and that doesn’t support the helmet story.

One of the arguments anti-helmet advocates push doesn’t prove to be true either. It’s true that registrations dipped slightly the first full year after the reinstatement, but then rose even faster than in the repeal years. If other states are like Louisiana, then, a helmet law doesn’t discourage those who want to ride from riding.

In fact, between helmeted and unhelmeted, injuries outpaced registrations in all but 1999. The helmet story, then, doesn’t hold up as told. While helmets do prevent some fatal injuries and reduce or prevent some lesser ones, helmets alone are not sufficient to make riders safe on the road.


[i] It may be of interest that the lead data analyst for the NHTSA report was Helen Weinstein, who, according to the Preusser Research Group site, “holds the M.S. degree in Science from Simmons College. She was elected to six successive two-year terms on the Trumbull (CT) Town Council where she has served as Chairman of the Finance Committee, Vice Chairman of the Council and Chairman of the Council.” She is the only employee that is referenced in terms of motorcycling and yet has no background in traffic safety nor motorcycling as a basis for analysis of the data.  http://www.preussergroup.com/

[ii] See: http://www.fhwa.dot.gov/policyinformation/. 2008 is listed by itself. For earlier years, choose vehicles under the category Quick Find.

Beyond fatalities: motorcycle injuries and the Louisiana Experiment

February 10, 2010

The helmet story told by safety professionals also claim helmets change the equation so that those who would die without one are only injured. Injuries, then, should be important—and yet we hear little about them.  So let’s look at injuries in the Louisiana Experiment and see if the helmet story proves true:

We’ll use the data from Louisiana’s Highway Safety Research Group (LHSRG) through Louisiana State University that breaks injuries down into moderate, severe and fatal in terms of helmeted and unhelmeted riders.

What is a Severe or Moderate Injury?

LHSRG doesn’t define what comprises severe or moderate injuries but we’ll assume the KABCO injury coding scale was used[i]. If so, severe would translate to incapacitating injuries and moderate to non-incapacitating injuries. Incapacitating injuries would be those that are not fatal but prevent the victim from performing activities s/he was normally able to do before the crash—for example, fractures or concussions. Moderate injuries would then be those that are obvious at the scene but aren’t either fatal or obviously incapacitating—for example, sprains, contusions or many (but not all) lacerations.

The following graph tracks each kind of injury for both helmeted and unhelmeted riders. It should be kept in mind that riders suffer and die from a variety of injuries that do not involve the head in any way including chest trauma, internal bleeding, ruptured organs. Wearing a helmet will not prevent those.

During the repeal years, both helmeted and unhelmeted injuries are closely clustered After reinstatement there’s a huge separation. However, during this time, helmet use never dropped below 42 percent while after the reinstatement helmet use rose to 98 percent and that could explain the clustering. Even so, unhelmeted injuries of all kinds outpaced helmeted ones.

In both conditions and as one would expect, there’s more moderate injuries than severe ones and more severe injuries than fatalities.

Otoh, there’s also an increase in injuries in the reinstatement years that’s not explained by more helmeted riders . For example, in 1999 injuries totaled 512. In 2002—two full years into the repeal—the total injuries for all three kinds of crashes was 619—a 21 percent increase. In 2006—two years after the reinstatement—the total was 861. In four years, then, injury crashes had gone up 39 percent or almost double the percentage increase from the midst of the repeal years.

During the repeal years, there’s also more fluctuation between the various kinds of injuries for both helmeted and unhelmeted riders. And during the reinstatement years, the kind of injuries are more closely clustered according to helmet use/non-use. This is particularly evident for helmeted injuries. There is no apparent reason for this.

Unhelemted injuries

Let’s look more closely at each condition in terms of the actual numbers of injured riders.

Under the repeal years, unhelmeted fatalities rose for the first four years. This what the helmet story would tell us to expect as more riders chose to ride without a helmet. The uptick in severe and fatal injuries and vast increase in moderate ones could simply be the result of a huge influx of unhelmeted riders.

Severe injuries rose as well, however, in 60% of the years, there’s almost no difference between severe and fatal injury numbers. This relationship between severe and fatal injuries is much tighter after the reinstatement than before and there’s no obvious reason why that should be.

The bulk of injuries are moderate, which would be expected but there appears to be no correlation between moderate and severe injuries as there is between severe and fatal injuries.

The helmet story implies that helmets prevent fatalities and turn them into moderate or severe injuries and reduce severe injuries and turn them into moderate ones. The behavior of the three kinds of unhelmeted injuries, though, doesn’t support that even though fatalities did rise as predicted.

After the reinstatement, however, a closer relationship between moderate and severe/fatal crashes appears among the unhelmeted and the moderate injuries plummet. Why would this happen?

Helmeted injuries

So let’s examine that by looking at the relationship between injury severity and helmet use:

In some ways it’s almost the reverse image to unhelmeted fatalities: overall, there’s a closer relationship between moderate injuries and severe ones—and a closer relationship between severe and fatal injuries—during the repeal years and a looser one once the universal helmet law was reinstated. But it is basically a mirror image—and that’s something that

There are some differences: while moderate injuries zoom up under reinstatement, there’s no wild fluctuation from year to year. And, from 2007-2009, moderate and severe injuries appear to correlate very well however, this is not seen in fatalities. Three years, though, may represent a blip rather than a trend.

Moderate injuries are, by far, the preferred outcome—the increase in moderate injuries in the reinstatement years would be a positive sign if the severe and fatal injury rate was depressed as a consequence as it suggests that helmets are effective in changing outcomes in the same kind of crashes.

But we saw that moderate injuries zoomed up under the unhelmeted condition as well.

Moderate injuries are the normative outcomes of certain kinds of crashes—such as low-sides where riders don’t impact a solid, fixed object. Severe and fatal injuries are the common result of crash configurations—such as frontal impacts.

The helmet story hangs on whether helmets really do turn fatalities into serious injuries and serious injuries into moderate ones so, let’s compare apples to apples by the percentage of each kind of injury:

Unhelmeted Injuries by Percentage
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Fatal 11.5 7 9.8 12.7 13.4 11.6 11.3 6.7 10.1 15.4 14
Severe 23 18.7 16.1 23.9 17.5 18.7 13.9 13.5 22.4 21.9 27.1
Moderate 65.4 74.2 74 63.3 69.3 69.7 74.8 79.6 67.4 62.6 58.8
Helmeted Injuries by Percentage
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Fatal 6.5 10.1 6.2 5.7 7.1 8.1 8.9 10.6 8.2 7.3 10.9
Severe 13.8 12.9 11.1 17.5 17.5 16 13.8 15.7 14.4 16.9 14.8
Moderate 79.6 76.9 82.2 76.8 72.2 75.8 77.2 76.3 77.4 75.7 74.3

Overall, there’s an extremely stable relationship between all kinds of injuries: moderate ones are the overwhelming majority for both conditions followed by severe then fatal ones.

Moderate injuries under both conditions over the entire time span averaged between 69 percent (unhelmeted) and 76 percent (helmeted)—but in both conditions, the average percentage dropped slightly after reinstatement.

However, helmeted moderate injuries averaged out, over the eleven years to be 7.76 percent lower than unhelmeted ones. Averaged helmeted severe injuries were 4.76 lower and fatalities were 4.75 lower than unhelmeted averages.

The helmet story, then, held up in that regard: if all things were equal and helmets were the only variable—which they may not be—then helmets appear to have made a small difference when it came to severe and fatal injuries. Otoh, less than a 5 percent difference is not seen to be statistically significant. But, as one reader points out, if you’re the one it made a difference for, it matters a lot. Even so, this presumes that the injuries that killed or wounded the extra five percent were head injuries—and that may or may not be true.

However, there’s less difference between the percentage of severe and fatal crashes than we may have expected. The following chart presents the difference between fatal and severe injuries for each condition:

The difference between severe injuries and fatalities in Louisiana
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009
Helmeted 7.3 2.8 4.9 11.8 10.4 7.9 4.9 5.1 6.2 9.6 3.9
Unhelmeted 11.5 11.7 6.3 11.2 4.1 7.1 2.6 6.8 12.3 6.5 13.1

In eight out of eleven years (72.7%) there was a greater difference between unhelmeted severe and fatalities and helmeted severe and fatalities. Which is something the helmet story wouldn’t have predicted.

The helmet story in Louisiana appears to be like rider training and licensing: it should be true that helmets save lives—they just don’t save then in statistically provable ways.

However, if we break down the averages into repeal and reinstatement years, helmeted fatalities went up almost 2 percentage points under reinstatement while severe injuries remained almost the same and moderate injuries went down. In terms of helmeted injuries, the increase was entirely in fatalities.

Otoh, the percentages of unhelmeted injuries remained almost identical during repeal and reinstatement years. Whatever is driving the difference in helmeted deaths, either it’s not having the same effect on those who do not wear helmets or it’s negating the helmet benefit in some ways.

Although 2 percent is tiny—it’s still an alarming development simply because, over several years, that increase was solely in helmeted fatalities and not in severe injuries.

Since we see the same pattern with moderate-fatal injuries (though more exaggerated under the unhelmeted condition) it raises the obvious possibility that the differences are more attributable to the number of different crashes that varied from year to year that drove injury rates rather than helmet use.

In addition, we see that while helmeted statistics performed slightly better overall but worse in reinstatement years while unhelmeted statistics were the same it also points to some other factor that’s operating. It could be that a certain number of crashes themselves are becoming more severe and negate the helmet’s safety benefit to the same state as riding helmetless.

Otoh, we could be seeing off-setting or risk-compensation or risk homeostasis occurring or adverse recruitment among helmeted but not unhelmeted riders. More on that in the future.

In the next entry, we’ll briefly compare injuries to registrations.


[i] The KABCO coding scale: K=Killed; A=Incapacitating Injury; B=Non-Incapacitating Injury; C=Possible Injury; O=No Injury; and U=Injured, severity unknown.

The strange case of Louisiana and helmet-no-helmet-helmet…

February 4, 2010

We return now to helmets since they are, beyond a doubt, the most often touted measure to increase motorcycle safety. In the next two entries, we will examine one state’s data over the same ten-year period we looked at in terms of crashing. What we will find illustrates many of the problems with motorcycle safety:

Louisiana is a unique case when it comes to motorcycle safety: Like almost all other states, a universal helmet law was passed in the 1960s (1968, to be exact) and then  modified it in 1976 to only apply to those under 18. Then legislators passed a universal helmet law again in 1982. Seventeen years later, the law was modified once again to require only those under 18 or those without coverage of at least $10,000 in medical insurance to wear a helmet and was in effect in August of 1999. Five years later, in 2004, the universal helmet law was reinstated.

During the same time frame that we examined crashes in terms of three kinds of crashes (fatalities, injuries and property-only crashes), then, Louisiana didn’t have a universal helmet law and then did have one. It is, then, a good state to see the effects of helmet and non-helmet use and the effect of a helmet law in terms of fatalities and injuries.  In this entry we look only at fatalities.

Louisiana in comparison to national picture

As in the rest of the USA, motorcycle fatalities increased from 40 in 1998 to 87 in  2006 or 117.5 percent. In 2008 fatalities were 77 or 92.5 percent and then to 92 in 2009. Overall, then Louisiana’s fatality toll rose 130 percent in eleven years. This is over the national percentage over the same time span.

As in the rest of the USA, motorcycle registrations were increasing in Louisiana during these years—though there are no publicly reliable statistics to document the increase—not even for NHTSA.[i] While the researchers who prepared the report on the effect of the helmet law repeal dismissed the importance of increasing registrations on crash rates, others would strongly disagree.  As we’ve seen in other states we’ve examined, registrations did not increase unilaterally in every state nor from year to year. The missing data, then, leaves a huge gap—if motorcycle safety is a puzzle, then this is information we need to solve it.

Observed helmet use over the ten years

In the years when the universal helmet law was in effect, between 87-100 percent of riders wore them. In the years without mandated helmet use, usage dropped immediately to 52 percent then rose to about 60 percent, dropped to 48 percent rose again to about 60 percent and stayed there until the universal helmet law was reinstated when observed helmet use appears to be 98-99%.

Unsurprisingly, when helmet use dropped unhelmeted fatalities went up[ii] and helmeted fatalities went down. And, unsurprisingly, when the mandate was reinstated, helmeted fatalities went up.[iii]

Studies were done, papers and reports were written to document the effect of the helmet law repeal—and then the reinstatement. Including NHTSA who released a report, “Evaluation of the Reinstatement of the Motorcycle Helmet Law in Louisiana”.

And the stats were astonishing—unhelmeted fatalities increased by 40% the first year and 42% the second year after the repeal and dropped 64% the year after the universal helmet law was repealed. It seems to prove the case—and is religiously held by helmet proponents: helmets save lives.

And, as helmet-proponents would expect, helmeted fatalities were under-represented compared to observed helmet-use:

And unhelmeted injuries were over-represented to non-use:

The helmet story seems to be justified.

However, if we look without preconceptions more closely at the actual numbers, that’s not the full story—and by not telling the full story, motorcycle safety researchers have not served riders well. The data in the following chart Data taken from the Louisiana State University Traffic Safety Research Group traffic safety data reports.

UnHelmet Fatalities Year-to-Year ChangeUnH Estimated Non-Helmet Use Total F Fatality Increase from prior year Observed Helmet Use Year-to-Year Change HEL Helmet Fatalities
1999 15 3% 40 14.2% 97% 25
2000 21 40% 48% 50 25% 52% 16% 29
2001 36 42% 41% 53 6% 59% -41% 17
2002 41 14% 58% 58 9.4% 42% 0% 17
2003 55 34% 40% 77 32.7% 60% 29% 22
2004 36 -34% 40% 68 -11.6% 60% 45% 32
2005 13 -64% 2% 70 -2.9% 98% 78% 57
2006 8 -38% 2% 87 24.2% 98% 38% 79
2007 14 43% 73 -16% -25% 59
2008 19 36% 77 5.4% -1.7% 58
2008 15 -21% 91 18.1% 31% 76
Totals 258 653 395

The NHTSA report doesn’t note that once the law was reinstated,

helmeted fatalities went up 45% then 78% then 38%. Iow, equally scary percentages are found on both sides of the Louisiana Experiment.

In fact, in 2004—the year of reinstatement—unhelmeted fatalities dropped 23—but helmeted fatalities rose 25. It’s almost as if it was simply a trade-off: unhelmeted deaths became helmeted deaths. This is the first indication that even though helmets save lives, their absence doesn’t drive the increase in motorcycle deaths.

While it is true that unhelmeted fatalities increased every year, however helmeted fatalities also increased 8 out of the 10 years—and that included two years when helmet use was depressed. This is the second indication that helmet use is disconnected from the rise or fall of fatalities in essential ways.

Ultimately this is the scariest thing of all: During these years, Louisiana’s motorcyclist death toll soared and helmeted fatalities tripled while unhelmeted fatalities in 2008 returned to exactly what they were in 1999.

The large point is this: the issue isn’t helmet effectiveness. Focusing merely on helmet use or encouraging riders to wear them simply doesn’t address why those fatal crashes are occurring more and more often. In this way, the increases on the helmeted side of the equation are more troubling since the additional protection helmets offer were insufficient in preventing deadly injuries.  We’ll return to this point in the next entry.

In reality, small numbers

But the focus on helmet use disguises something that is also essential to really understanding what’s happening with riders: small numbers make for big—but misleading—percentages on both sides of the equation. And in Louisiana, the numbers are sometimes very small:

2000: Helmet use was 52%. Fatalities increased by 10 riders.

Unhelmeted fatalities up by 6.

Helmeted fatalities up by 4.

2001:Helmet use: 59%. Death toll increased by 3.

Unhelmeted fatalities went up by 15.

Helmeted fatalities down by 12.

2002: Helmet use: 42% fatalities. Fatalities up by 5.

Increase was solely accounted for by unhelmeted deaths.

2003: Helmet use 60%. Fatalities up by 19.

Unhelmeted fatalities up by 14.

Helmeted fatalities up by 5.

2004: Helmet law use 60%. Fatalities down by 9.

Unhelmeted fatalities down by 19.

Helmeted fatalities up by 10.

2005: Helmet use was 98%.[iv] Death toll increased by 2.

Unhelmeted fatalities down by 23.

Helmeted fatalities up by 25.

2006: Helmet use 98%. Fatalities increased by 17.

Unhelmeted fatalities down by 5

Helmeted fatalities up by 22.

2007: Estimated helmet use 98%. Fatalities decreased by 14

Unhelmeted fatalities up by 6.

Helmeted fatalities down by 20.

2008: Estimated helmet use 98%. Fatalities increased by 4.

Unhelmeted fatalities down by 5.

Helmeted fatalities up by 18.

Small numbers yield large percentages—but skew the interpretation

There’s several things to observe: If  fatalities can legitimately be expected as a function of the numbers, some kind of increase could be—and maybe should be—expected because motorcycle registrations were increasing. But even as the pool of motorcyclists was growing fatalities increased by 5 or less in four of the ten years.

And 5 or less are surely small numbers—and yet they can loom large and appear to be more important than they perhaps are. For example, a decrease of unhelmeted 5 deaths in 2005—the year after the helmet law reinstatement—resulted in a decrease of 38% and an increase in 5 helmeted deaths results in a 29% increase. Using percentages to make a point without including the numbers can lead to inaccurate analysis and, in this case, exaggerate the supposed effect of the reinstatement when the reality is that people who might have died without helmets died with them on.

A pattern of wild fluctuations

Louisiana’s pattern is one of wild fluctuations where fatalities creep up or down by 5 or less or soar by 22 one year and plunge the next by 20 then rise to 18. This pattern of dramatic year-to-year shifts is not seen in states with large numbers of fatalities where they produce smaller percentages of increase.

Such wild swings raise the possibility that crashes have much more to do with random factors or at least factors that are not considered and therefore not accounted for than any crash causation study to date has considered.

While Louisiana’s motorcycle registrations are shrouded in mystery for some inexplicable reason, the state does provide data on injuries as well as fatalities—and that’s where we follow the helmet story next.


[i] Observed helmet use statistics interpreted from Evaluation of the Reinstatement of the Motorcycle Helmet Law in Louisiana, NHTSA, Number 346 May 2008.

[ii] The helmet law was repealed in August. The death toll went up by 5 but we don’t know if they were helmeted or not.

[iii] Evaluation of the Reinstatement of the Motorcycle Helmet Law in Louisiana.

[iv] Ibid.  According to NHTSA and quoted in other studies.

No Phone Zone

February 1, 2010

For those of you who do believe that using cellphones–hands-free or hand-held– are distracting and that distraction can cause crashes, here’s a chance for you to put your words into action–or, rather, action promising no action:

Oprah Winfrey has a No Phone Zone Pledge on her site that reads: “I pledge to make my car a No Phone Zone. Beginning right now,  I will do my part to help put an end to distracted driving by not texting or using my phone while I am driving.  I will ask other drivers I know to do the same.  I pledge to make a difference.”

If you agree with the pledge, add your support by going to the No Phone Zone page.

And, if you agree that cellphone use can cause crashes, pass on the link.

Of course, it’s easy enough to sign the pledge–harder to put it into action…

A friend of mine has changed his sig line–and I’m rewriting it a bit: “Honk, if you love Jesus. If you’d like to meet him in person,   just keep texting.”