Michigan Motorcycle Helmet Case Study
In 2012, Michigan decided not to use its head and revoke laws requiring motorcyclists to wear helmets while driving. Looking back years later, did anything change?
While walking through datasets of automobile accidents, there are lot of sources that talk about statistics of types of crashes and deaths. An interesting test case took effect in Michigan around motorcycle helmets and I wanted to investigate if they made the right decision. The best case scenario for Michigan is that accidents could stay consistent and not have an increase in deaths or severe injuries. I can imagine as autonomous vehicles and safer public driving, motorcyclists in other states might be pushing legislators to make the same decision. This article is dedicated to look at the following topics:
- Did it change rider behavior?
- 2.How did not wearing helmets affect injuries and mortality rates?
Rider Behavior
It’s easy to see why Michigan lawmakers could look at data prior to 2012 and not think that helmet usage was making a big difference. The years leading up to the law change showed the majority motorcycle fatalities resulted with riders who were wearing helmets. Viewing the area chart below shows the distribution between helmet and non-helmet motorcyclist fatalities.
There is an obvious change in rider behavior starting in 2012. From 95% of rider fatalities wearing helmets, almost half of all fatalities came from riders who were not wearing helmets. In fact, the 2016 year saw more non-helmeted rider fatalities than riders who were wearing helmets. We also see the same impact among motorcyclists injuries
Accident Types and Fatalities
Building off of the last graph, although behavior changed in riders wearing helmets, it didn’t really change the total number of accidents that happened on the road. The decision to wear a helmet changed but it does not appear that riders were more reckless than before. Since the amount of accidents have not changed, have the types of accidents changed?
There are three types of injuries that are classified by Michigan state police for automobile accidents. For this analysis, we will only be focused on injury types A and B.
Looking at total injury types over a time span, we can see that in 2012 there was a spike in both types of injuries followed by a few years of a decreasing trend in injuries.
However, if head gear is thrown into the mix, we can get a better picture of who is experiencing the majority of these injuries.
For both type A and B injuries, starting in 2012 motorcyclists who were not wearing helmets were responsible for a much larger portion of those injuries. Riders who were wearing helmets had a decreasing trend in total accidents prior to the 2012 year, so the main question should become if those people would have had those injuries if they were wearing helmets leading to an overall downward trend in all injuries or would those riders would have the same injuries regardless if they had a helmet on or not.
Mortality rates also give two different perspectives on motorcycle crashes. Mortality rates are calculated as the total number of deaths divided by the total number of accidents. In 2012, the total morality jumped from 4.3% to 4.9% but continued to follow the overall linear trend seen from 2009–2018. If you look at the mortality rates between accidents where helmets were involved, they are considerably lower than mortality rates of accidents without helmets. Although the linear trends for the helmet types look significant, the slopes were not statistically significantly different than 0 meaning they are not significantly changing over time. On the other hand, the overall mortality rate did have a statistically significant trend.
This can be interpreted as mortality rates have an increasing trend over time, but are not statistically driven by whether people wear a helmet or not.
Conclusion
There was a significant change in rider behavior and accident results after the helmet law was lifted in 2012.
- What used to be 90% of motorcycle deaths were riders wearing helmets changed to about 55%
- Annual accidents stayed relatively constant but a much larger share of them occurred with riders without helmets
- Both injury types of A and B saw large increases in non-helmet riders and a downward trend in accidents with bikers wearing helmets
- Mortality rates have increased linearly over time but have not been impacted by whether the rider is wearing a helmet
Should Michigan reverse their decision and mandate motorcyclists to wear helmets? The data would say that motorcycle deaths have not been impacted by the decision and have continued to stay on consistent trends. However, the same cannot be said when it comes to injuries. Total injuries have stayed consistent but non-helmet accidents have increased by multiples. It is tough to conclude whether those head injuries would have occurred had the person been wearing a helmet.
If a state is thinking about mandating this rule they should go in with the knowledge that deaths will not change, but conscionable about the shift in severe injuries that might have been preventable by wearing a helmet.
References:
- Michigan State Police - https://www.michigan.gov/msp/0,4643,7-123-1586_3501_4626---,00.html
- NHTSA - https://www.nhtsa.gov/content/nhtsa-ftp
- Buckfire Law - https://buckfirelaw.com/case-types/motorcycle-accidents/
