Building Momentum for a Safe System Approach to Reduce Road Traffic Injuries in the United States

Roadway designs have an effect on how people drive. Designs that prioritize the flow of cars often do so at the expense of safety for those who are walking and biking.¹ Dangerous designs are more likely to be located in low-income neighborhoods, leading to disparities in road traffic injuries. As a result, communities of color experience higher crash death rates than those in predominantly White areas, and low-income neighborhoods have fatality rates that are three to four times higher than those in wealthier areas.²

Vision Zero or Safe System interventions can address these disparities. In 2014, New York City was one of the first US jurisdictions to introduce a comprehensive range of policies termed Vision Zero.³ Vision Zero is so called because of the commitment to no deaths from road traffic crashes and was inspired by the Safe Systems approach pioneered in Sweden and the Netherlands in the 1990s. In the Safe System approach, the focus shifts from “How can people use the transportation system more safely?” to “How can the system be made safe for people to use?” The Safe System implementation in the United States gained momentum owing to the 2021 Bipartisan Infrastructure Law, which introduced a new Safe Streets and Roads for All grant program. This program provides $5 billion over five years to support local improvements that align with Safe System principles.⁴ The US Department of Transportation followed this with the first national roadway safety strategy based on the Safe System approach.⁵

The study by Dragan and Glied (p. 633) in this issue of AJPH notably highlights three important aspects of Vision Zero programs. First, Vision Zero is designed to enhance the safety of all road users, rather than targeting vehicle occupants only. Consequently, it led to a dramatic reduction in road traffic injuries among the most disadvantaged groups. Second, Vision Zero policies are scalable and sustainable.⁶ Most interventions included in the program involve changes to the infrastructure and roadway environment that are “self-enforcing” rather than requiring continual policing for effectiveness.⁷ Third, because they used Medicaid data, the authors were able to quantify the cost savings resulting from Vision Zero policies, which is one of the first times that health benefits have been quantified in the US context.

Dragan and Glied’s findings are particularly encouraging because the Safe System approach is intended to improve both safety and equity. Using Medicaid claims data from New York City and surrounding counties, they demonstrated that Vision Zero policies disproportionately benefited low-income and Black residents in terms of road traffic injuries. The central goal of a Safe System is zero traffic deaths and serious injuries, and this demands investment according to need. Communities that have previously suffered from underinvestment will necessarily require more resources to reach zero traffic deaths than communities where safety improvements have already been made. Because Safe Systems cannot be implemented everywhere at once, areas most in need can be prioritized.⁷

The Safe System approach demands a careful analysis of safety issues and identification of root causes. For instance, intersection crashes, which contribute to approximately one quarter of fatalities and about half of all injuries, prove lethal because of the vulnerability of conventional intersection layouts to common human errors such as distraction and inattention. These errors often result in high-speed side-impact collisions that exceed human injury tolerance thresholds. In the Safe System framework, high-risk intersections are replaced by roundabouts, which reduce speeds and alter vehicle trajectories to lessen the impact of typical driver errors such as failure to notice traffic signals, oncoming vehicles, or pedestrians. Roundabouts are engineered to require drivers to decelerate and align with the flow of traffic, thereby reducing the likelihood of severe injuries by preventing deadly high-speed head-on and side-impact collisions.

As mentioned previously, roundabouts and other strategies in the Safe System framework are engineered to be self-enforcing. These designs incorporate physical elements such as narrowed lanes, speed humps, tighter corner-turning radii, and chicanes to guide drivers toward safe speeds, rather than relying solely on posted speed limits. Roads are planned so that the comfortable driving pace aligns with the safe speed. Additionally, features such as separated bike lanes and intersections equipped with clearly marked crosswalks, raised medians, and pedestrian refuge islands serve to decelerate traffic and ensure that pedestrians and cyclists remain visible to drivers. By reducing speeds, reaction times are increased, making crashes less probable and mitigating the severity of any conflicts that do occur. Implementation of the Safe System approach entails a dedication to proactive safety enhancements, introducing them preemptively in all areas prone to crashes, rather than delaying action until injuries occur. This approach emphasizes prevention over reaction to reduce crashes and can be adapted to communities of diverse sizes and demographics.

A question that naturally arises is why the United States has only recently adopted Safe System approaches? One reason is the entrenched institutional resistance to large-scale change. Existing road design standards and practice guidelines are codified in manuals and protocols, whereas most funding channels have incentivized traditional practices rather than adopting a Safe System approach. Although institutional inertia does not justify maintaining the status quo, overcoming it will demand concerted efforts. Another obstacle that must be overcome in the United States is the need to rectify past and present disparities in transportation system investments. Although the Safe System approach holds promise for addressing historical injustices in transportation, implementing this approach necessitates sensitivity and a steadfast commitment to inclusive planning processes that genuinely engage communities.

The United States is still in the early stages of adoption of the Safe System approach. Despite political support, a relatively modest number of jurisdictions have adopted the comprehensive set of strategies that New York City implemented as part of Vision Zero. The article by Dragan and Glied adds much needed momentum to the movement in this country. Jurisdictions considering Vision Zero policies should proceed with optimism that implementation will advance both safety and equity.