Much of the focus on the intersection of public health and transportation is on the health outcomes related to our current transportation system. In the United States, the number of people that die in traffic crashes each year is far higher than other industrialized countries, and transportation accounts for a large portion of emissions that contribute to a myriad of health issues.

Despite the large burden that transportation places on our health and wellness, public health thinking has yet to permeate transportation policy and practice. The one exception to this is vehicle design. In the late 1950s and early 1960s, public health experts began to think of traffic injuries according to the classic public health model of host-agent-environment relationships. William Haddon, the first administrator of the National Highway Traffic Safety Administration (NHTSA) was a medical doctor, and applied a public health model to transportation known as “The Haddon Matrix.” Since then, NHTSA has regulated passive vehicle features into the design of vehicles that does not require any action on the part of those operating the vehicles. These features have saved countless lives over the past 50 years.

Thus, public health thinking was embraced in vehicle design as it relates to vehicle occupants. However, transportation engineers and other road safety practitioners have yet to fully embrace the public health approach. This is embodied by the traditional approach to traffic safety represented by the Three E’s: engineering, enforcement, and education. Recent iterations of the E’s have added equity, evaluation, emergency response, and engagement. With each new E, we dilute their meaning, and shift fault away from engineers, planners, and policy makers to individual users.

When viewed through the lens of the Health Impact Pyramid, the false equivalence implied by the E’s framework is apparent.  Traditionally, traffic safety efforts have emphasized individual behavior change through education and enforcement. Although well intentioned, these tend to be the least effective public health interventions, codified at the top of the pyramid under “Counseling and Education.” Former Director of the Centers for Disease Control and Prevention Dr. Tom Frieden writes “the need to urge behavioral change is symptomatic of failure to establish contexts in which healthy choices are default actions.” Engineering interventions, however, are classified under “Changing the Context to Make Individuals’ Default Decisions Healthy,” near the base of the pyramid. Interventions that change the built environment increase population health impact and require less individual effort. Thus, focusing efforts on creating a road environment that prioritizes safety will increase the odds that fewer people will needlessly die on American roadways each year.

Figure 1 The Health Impact Pyramid (from Thomas R. Frieden, 2010:A Framework for Public Health Action: The Health Impact Pyramid. American Journal of Public Health 100, 590-595, https://doi.org/10.2105/AJPH.2009.185652)

The Health Impact Pyramid is also a more flexible and inclusive means of thinking about interventions and policy. For example, equity is rightfully included as one of the “E’s” in many traffic safety and Vision Zero programs. However, emphasizing enforcement as a primary Vision Zero strategy can directly contradict goals for equity within Vision Zero programs. When viewed in terms of the Health Impact Pyramid, equity is literally and figuratively foundational to an effective Vision Zero program within “Socioeconomic factors.” The social determinants of health are the primary drivers of health disparities in the United States, and the same is true for transportation. Black people, and other people of color die at a disproportionate rate while walking, and are exposed to higher levels of transportation emissions.

It is time for transportation professionals, and especially those working on Vision Zero programs, to throw out the traditional “E’s Approach.” The E’s are a relic of the traditional traffic safety approach, which has resulted in thousands of needless deaths and injuries. Vision Zero and the Safe Systems call for a new approach to traffic safety. Rather than simply connecting risk in the transportation system with health outcomes, traffic safety professionals should adopt the public health approach in their work. The Health Impact Pyramid is a concise and clear means of determining the population health impact of transportation policies and interventions. By emphasizing public health in Vision Zero and other Safe Systems policies, transportation professionals can focus on the interventions that are likely to save lives, prevent injuries, and create a transportation system where no one need fear serious injury or death on the road.

The views expressed above are those of the author and do not necessarily reflect the views of the Eno Center for Transportation.