March 4, 2024 BY Tiffany Smithin News, Webinars

Harnessing Public Health Principles for Vision Zero: Near and Long-Term Strategies

With increasing urgency, researchers, advocates and practitioners are asking the question: How do we make our roadway safety efforts in the U.S. more effective and equitable? And increasingly, the most promising responses draw inspiration from the strategies used by the public health profession. 

While transportation and public health have long shared a symbiotic relationship, unfortunately,  public health principles of injury prevention have largely been underutilized in roadway safety work. Oftentimes, when we think about what it means to integrate public health and transportation, we focus on collaboration efforts, such as sharing injury data or promoting active transportation. But the need goes far deeper than just collaboration. Real change will happen when we integrate public health thinking and strategies into transportation work at every level. This means transportation professionals should embrace their roles as public health professionals and as stewards of safe, healthy and equitable transportation systems. Read more about how we suggest Thinking & Acting Differently for Vision Zero and the important new research that inspired us!

As follow-up to that work, we joined with the Institute for Transportation Engineers (ITE) to host another discussion with David Ederer, of the Centers for Disease Control and Prevention (CDC), and Meghan Mitman, of Fehr & Peers, to explore the benefits of and steps to infuse public health-inspired approaches into transportation safety work and the key barriers we will have to address to embrace these approaches. Check out the slidedecks for an overview of the discussion. 

Following are some of our key takeaways:

The higher the energy, the greater the severity of a crash. Source: Federal Highway Administration (FHWA)

1 - Target the Root Causes of Serious Crashes: Energy and Exposure

A key lesson from the public health realm is that we must better understand the critical causes of serious and fatal injuries and what is actually required to prevent injuries or, at least, lessen their severity. A key example of this is focusing on the structural implications of energy, specifically the impact of energy on the human body, which ultimately determines whether or not a crash will occur and how severe it will be. Recognizing how lethal energy transfer is in crashes, a public health approach to roadway safety means system designers (planners, engineers, policymakers) prioritize interventions that prevent people from being exposed to high levels of kinetic energy transfer, or, in other words, keep the impact energy from speed and vehicle mass at levels that do not result in severe injuries or death. And reduce exposure to this risk. This underpins the most effective speed management strategies. 

In practice, this might look like lowering speed limits and re-designing a roadway to deter high speeds, recognizing that the higher the speed is, the higher the likelihood that a crash is serious or even fatal. Another example is the use of roundabouts versus stop signs or traffic signals; because of their design, crashes in roundabouts happen at slower speeds and different impact angles, which decrease the amount of kinetic energy transferred. An effective strategy is ensuring vehicles are designed in ways to soften the blow of collisions, with safety features such as automated emergency braking and pedestrian detection systems. Other examples include the development of three-point seat belts, which distribute force across the body to mitigate injuries when crashes occur for those inside the car, and Intelligent Speed Assistance systems that deter drivers from going dangerous, high speeds.

Shifting focus to address the root causes of serious crashes versus concentrating on the risks also has important equity implications. For instance, someone relying on public transit to commute to their night shift may be disproportionately exposed to poor safety conditions, such as dimly lit crosswalks, incomplete sidewalks, bus stops and housing on or near high speed roads and more likelihood of drunk drivers. To focus on just the risks would be to recommend that this person wear bright clothing to “be safe” or avoid commuting at night, when more crashes happen. But these strategies do not take into account the realities of the environment and situation; instead they punish this person for their socioeconomic status and fail to address the root causes of the safety problem - the unsafe built environment and conditions, which are what really need attention.

2 - Focus on Strategies that Impact Entire Communities, Not Just Individuals

Public health work focuses on prevention – to reduce or eliminate the occurrence of health problems within a population.  And the prevention measures that work best are those that can apply to – and ultimately benefit– as many people as possible. These measures are what public health professionals describe as having a  “population health” impact, because they can reach and improve the health of communities by employing upstream approaches that everyone can benefit from, regardless of potential social, economic or physical barriers. 

For example, in the early stages of the Covid-19 pandemic, initial prevention measures focused on individual, preventative actions, such as handwashing and social distancing, which were especially important before a vaccine was available. However, because handwashing requires a lot of individual effort and social distancing, which not everyone can afford to do because of the nature of their employment, this leaves a lot more room for error. Therefore, they are not anywhere near as effective as a widely used vaccine. So, once a vaccine was developed and distributed, this population-level prevention strategy became most effective. While both the individual-level efforts and population-level strategy had roles to play in prevention, ultimately the vaccine provides greater protection and yields bigger safety benefits to far more people, with far less individual effort.

The Safe System Pyramid was adapted from the Health Impact Pyramid to more fully address roadway safety needs.

We can draw lessons from this for roadway safety work. Let’s take the example of curbing dangerous speeds. Today, many transportation safety initiatives might focus on public education or PR campaigns that urge drivers to slow down and be safe. And while these outreach campaigns may have a place in a larger safety strategy, they are insufficient alone because they rely on individuals to make the safest choice – even when the environment and other signals around them actually encourage them to speed up (ie. wide travel lanes with high speed limits, car designs that enable and even glamorize dangerous speeds). 

Alternatively, more effective and appropriate upstream strategies include altering the built environment to physically deter dangerous speeding and providing mixed land uses that allow for easier mode shifts to walking and bicycling. Examples include narrowing and/or reducing travel lanes, adding traffic-calming measures, such as roundabouts and speed humps, retiming traffic signals and lowering speed limits. Other strategies include making vehicles safer, such as adding automatic emergency braking systems, pedestrian detection features, Intelligent Speed Assistance and blind spot warning systems. While there are still individual choices to be made and room for individual errors, the physical environments and the vehicles themselves lend themselves to curbing the root causes and lessening severity when crashes do, inevitably, occur. 

What are next steps?

We're all invested in saving lives and already working hard to do so. So, instead of suggesting that we just need to work harder, we think it’s time we do things differently. Let’s focus on what is most important to lessen both crashes, overall, and crash severity: minimizing the impact of kinetic energy. It’s not just a theory, it’s physics

We know how to do this. We have the tools to separate road users in time and space, and to design roads and vehicles to be fundamentally safer (read: slower). Of course, this kind of fundamental change is neither fast nor simple. But it is possible. Several cities have reported zero deaths in 2023, including Alexandria, Virginia and Hoboken, New Jersey.

While we invest in making critical, transformative changes to how we approach roadway safety, we can also take smaller, near-term steps, such as the following:  

  • Share research on the Safe System pyramid and ITE’s new article on how to focus on kinetic energy with your colleagues and initiate conversations about how these ideas may play out in your community. Think about concrete steps, such as proactive, system-wide improvements (exs: lowering speed limits and replacing stop signs with roundabouts) or moving from prioritizing Level of Service to a Level of Safety
  • Identify low-hanging fruit safety measures that can be implemented and scaled up system-wide and relatively quickly, such as daylighting intersections, Leading Pedestrian Intervals (LPIs), improved pedestrian-scale lighting
  • Focus on raising awareness amongst policy makers about the importance and risks of speeds and what is actually shown to be effective at managing speeds for safety
  • Shift from merely educating community members about individual safe behavior to empowering them with tools to identify road safety problems in their neighborhoods and ways to advocate for change
  • Invest in community engagement, feedback or assessments that capture community insight into what safety changes are most important to people
  • Review your local capital improvement program to identify opportunities to infuse safety into all projects and, critically, to re-envision projects that are not safe system-consistent.
  • Identify and create an action plan to address barriers that you face in implementing any/all of these suggested next steps.

You can delve deeper into these concepts and examples by checking out our previous blog post, learning more about the Safe System pyramid framework and by exploring the slidedecks. And as you work to translate these public health concepts into on-the-ground change in your community, recognize that even if change feels too incremental or slow, with persistence and intention, we can reach a tipping point of transformative and systemic change to meaningfully advance our Vision Zero goals. 

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