Vision Zero and Safe Systems are public health policy.

John Snow's map of cholera cases in London is one of the 1st examples of modern epidemiology.

Civil engineers ended that outbreak, and transportation engineers must understand their role as public health professionals. https://twitter.com/Fam4SafeStreets/status/1374352176701657093

When Snow created his map, most people believed that disease was caused by bad or foul smelling air (Miasma theory).

He didn't buy that. Instead, he was interested in the *cause* of disease. He looked at the data and tried to discern a pattern and common factors among cases.

When I see these maps of high injury networks, I can't help but think about Snow's map of London cholera cases.

In transportation safety, we're still stuck in the "Miasma" theory of traffic crashes.

We ascribe cause to things that aren't the cause of injury like bad behavior or simply accept crashes as accidents.

Our practices reflect this. The E's framework was first introduced in the '20s touting the importance of engineering, education, and enforcement.

Since then we've added E's (equity, evaluation, etc.). We've made some good progress, but still have a ton of work to do.

Simply adding alliterative E's won't do any good. The Safe Systems approach is departure from the traditional approach to transportation safety.

When medicine transitioned from miasma to the germ theory of disease, everything changed. We can do the same in transportation.

Fortunately, @SecretaryPete understands that transportation policy is health policy. However, I'd argue that this is bigger than access to healthcare, as he defines it below. Instead, this is about getting transpo pros to think like public health pros. https://twitter.com/harrisongolden/status/1371518843680657412?s=20

So how can we think like epidemiologists? Start with basic public health and the epidemiologic triad.

Disease occurs when host (typically humans) interact with a causative agent (virus, bacteria) in specific environments that put one at risk.

The social determinants of health underlie these factors and influence all three. For example, race and place are intimately connected. Black Americans are disproportionately more likely to live in areas that have a negative influence on health.

This basic model helps understand causes. Malaria only occurs when a human cost comes into contact with a plasmodium species (agent). This most likely to happen in environments where vectors like Anopheles mosquitoes thrive.

When we understand causes, we can develop preventive measures to target the host, agent or environment. Can also influence the interaction between the 3.

E.g. we can make the environment less appealing to mosquitoes (drain wetlands), or use to decrease chance of infection.

The Safe Systems approach applies this idea to transportation safety.

The causative agent in traffic injuries is the transfer of kinetic energy. This is at the core of Vision Zero and Safe Systems.

Further, the Safe Systems approach/Vision Zero aims to prevent as many deaths as possible. In the same way that we're taking a moonshot to end cancer, we should set a goal to prevent all road traffic deaths.

Next Safe Systems and Vision Zero understand the role of the social determinants of health. Engaging with the community and building trust is key. John Snow worked with Henry Whitehead a (local priest) to build trust and dispel myths about the causes of cholera.

Public health interventions just don't work without public understanding of the problem, or trust that it can be fixed. This is an enormous issue in transportation.

Plenty of Vision Zero policies call for collaboration between transportation and health professionals.

That isn't enough. Transportation professionals are public health professionals and we must strive to think in terms of public health.

Way back when @PublicHealth had an engineering section, there was a debate about what a "Public Health Engineer" should be. This was back in the 1930s. At the time some forward thinking engineers understood their role in improving health.

Let's get back to that.

In my experience, planners have what I refer to as "public health consciousness." They know their shared history with public health. They understand the value of public health ideas and approaches.

For engineers, "It is not so important that he [or she or they] know how to build a sewer as that he know why sewers are necessary and what results may be anticipated from the discharge of their contents without treatment into a body of water."

Engineers focus on how to build roads (form), but need to think more about why they are necessary and what results can be anticipated when we build them (function).

We can create a new generation of public health engineers, and Safe Systems can guide us.