Editor’s Note: The recent spate of cycling traffic fatalities has been startling. The Bike Fed will be there to make sure that these tragedies are not forgotten. Where drivers are at fault, we will push for tough prosecutions or new laws, where necessary. But it’s also important to keep in mind that cycling is becoming much safer across broad populations. So we asked a national expert on that subject, Prof. Robert Schneider of the University of Wisconsin-Milwaukee, to pen this piece sharing his research into cycling safety in the U.S. We hope you find his work encouraging.
Mirroring a national trend, the number of bicycle fatalities in Wisconsin has increased in the last two years. After averaging approximately 10 bicycle fatalities per year over the last decade, 15 bicyclists were killed in Wisconsin in 2015, and there are more bicycle fatalities in 2016 than this time last year. One bicycle fatality—or any type of traffic fatality—is too many, as it represents the loss of a family member, a friend, and a member of our community. Clearly, we need to design safe roadways and provide high-quality bicycle facilities, educate drivers and bicyclists about safe behaviors, and enforce traffic laws.
Avoiding the implication that riding a bicycle on public roads is more risky than it is represents one of the challenges in promoting safety. Examining and detailing crashes and fatalities in the interest of promoting better bicycling has the potential to cause people to ride less.
Discouraging riding is a problem because research shows that higher levels of bicycling are generally associated with lower risk for any individual bicyclist: “safety in numbers.” Following this logic, reducing the number of riders is likely to increase the risk to those who do ride. Therefore, bicycle infrastructure, education, and enforcement strategies to improve safety should be complemented by more encouragement to ride.
What evidence do we have of “safety in numbers?
The first researcher to explain this concept was Peter Jacobsen. (You can find his analysis here). His study of multiple crash databases suggested that if Community A had twice as much walking or bicycling than Community B, each individual pedestrian or bicyclist in Community A had a 66 percent lower risk of being involved in a crash. Other researchers, including those at the University of California – Berkeley Traffic Safety Center and the National Academies of Science Engineering Medicine, found similar data to support safety in numbers for bicyclists and pedestrians.
Comparing crash rates over different time periods further validates safety in numbers.
For example, bicycle trips in the United States increased by 19 percent between 2001 and 2009, but the crash rate decreased from 0.209 fatal crashes per million bicycle trips to 0.164 fatal bicycle crashes per million bicycle trips. We also found evidence of safety in numbers when analyzing the Wisconsin crash data from 2006 to 2013.
Like other statistical relationships, there are exceptions to safety in numbers. For example, the steep increase in annual bicycle fatalities in Wisconsin in 2015 and 2016 may actually be an example of increasing bicycle activity and an increased fatality rate. However, we do not know how much bicycling occurred in Wisconsin during these two years. Even if these two years do not follow the overall trend in safety in numbers, the large body of research on this topic suggests that safety in numbers should generally hold in the long run.
In addition, more research is needed to understand why we see safety in numbers.
One explanation is that drivers are more aware of bicyclists in areas with more bicyclists and therefore drive more carefully around them. For example, if a driver sees you bicycling, that driver may be less likely to look down at his or her phone when approaching the next bicyclist. Another explanation is that safety in numbers is due to infrastructure, education, and enforcement actions that first create safer conditions so that people then choose to ride more. Both explanations likely contribute to safety in numbers. Regardless of which explanation is more prominent, the safety in numbers relationship is found in study after study. And if more bicycling can help increase driver awareness of bicyclists to any degree, encouraging bicycling can be a great way to complement other bicycle safety strategies.
Overall bicycle crash, injury, and fatality numbers are available from a variety of sources:
Wisconsin Department of Transportation - annual fatalities over the past five years)
These sources show that there has been an increase in the number of bicycle fatalities in the United States over the last five years or so and in Wisconsin for the last two years. However, those statistics do not indicate whether or not bicycling is becoming relatively safer or not. This is because the raw numbers are affected by the overall amount of bicycling activity within a given area over a given time period. The safety of any individual bicyclist is best represented by a crash or fatality rate (e.g., crashes per million trips; fatalities per million trips; crashes per million minutes bicycled). The safety in numbers relationship has been identified by examining crash and fatality rates.