In the wake of rising traffic fatalities, municipalities around the United States have been looking for a comprehensive solution to reduce or, more optimistically, eliminate traffic fatalities. Two complementary concepts have emerged in the last few decades as possible solutions designed to improve the accessibility and safety of roads across the world: Vision Zero and Complete Streets.
Both programs offer policy solutions and traffic interventions meant to improve safety, but the more heavy-handed interventions can also negatively affect the flow and speed of traffic. As is often the case in public policy, there are major tradeoffs to be considered when deciding which approach works best for safety’s sake.
What is Vision Zero?
Vision Zero approaches traffic safety with the stated goal of eliminating all traffic fatalities and serious injuries. The movement gets its name from what proponents claim is the “acceptable number” of traffic fatalities: zero. Central to the concept is that human error is inevitable, so the natural policy response from a Vision Zero perspective is to design roads in a way that assumes human error is inevitable, to some degree, and then minimizes users’ exposure to the conditions in which a crash is most lethal. This is typically accomplished through a mixture of traffic calming measures such as speed humps, road diets (which conventionally mean the conversion of an existing four-lane roadway to a three-lane roadway, with two through lanes and one center two-way turn lane), and reduced speed limits to lessen the severity of injuries from automobile impacts.
According to the Vision Zero Network, Vision Zero “is a strategy to eliminate all traffic fatalities and severe injuries, while increasing safe, healthy, equitable mobility for all.” It emphasizes a holistic and multidisciplinary approach to road safety, focusing on eliminating safety risk arising from human error and creating safe road environments.
The core principles of Vision Zero focus on safe system design through a few different means, such as:
- Engineering safer roads (typically in the construction stage—including bicycle lanes as part of a road’s plan rather than retrofitting them)
- Promoting safer speeds (this can be via lowering speed limits or by public campaigns for drivers to drive more slowly)
- Enhancing road user education and awareness (reinforcing the right of way, such as automobiles having to yield to pedestrians at marked crosswalks)
- Targeting high-risk locations on a network and implementing interventions to reduce crashes or the lethality of crashes (tightened shoulders at a high crash rate intersection, for example)
All of these factors are undertaken for the same central goal: reducing or eliminating the fatality risk from human error in road environments. In effect, Vision Zero advocates that roadways ought to be designed in a way that mitigates the impact of human error. Crashes are inevitable, so it follows that roads ought to be designed in a way to not only reduce the likelihood of a crash, but the severity of one.
Vision Zero has faced challenges and criticisms along the way. Some argue that the approach is overly idealistic and unattainable, but more policy-focused criticisms examine costs and tradeoffs. However, proponents of Vision Zero argue that it provides a clear moral framework and a long-term vision for road safety improvement.
What is Complete Streets?
Complete Streets is a design framework adopted by transportation planners and engineers in many U.S. cities to create safer, more convenient street designs and city layouts for all transportation users, focusing on pedestrians, bicyclists, and transit riders. The two strategies work together to encourage more travelers to choose alternatives to traveling by automobile.
Complete Streets offers an easy way to lower speeds, focusing (but not only) on converting existing four-lane roads to two-lane complete streets as opposed to new infrastructure, all without unnecessarily expanding the roadway. The National Complete Streets Coalition describes Complete Streets as:
…(A)n approach to planning, designing and building streets that enables safe access for all users, including pedestrians, bicyclists, motorists and transit riders of all ages and abilities. This approach also emphasizes the needs of those who have experienced systemic underinvestment, or those whose needs have not been met through a traditional transportation approach.
Smart Growth America describes it as a process, not a “product or single type of street.” It, like Vision Zero, focuses on a multidisciplinary approach to make streets safer for users, with a priority on non-automobile users, by focusing on a few key concepts:
- Lowered speeds to reduce fatality chance when a collision occurs, especially a collision between an automobile and a pedestrian or bicyclist
- Street design with safety and multi-modal use in mind (bicycle lanes, crosswalks, protected sidewalks)
- Marked crosswalks. More crosswalks for pedestrians means more mobility for pedestrians and reduces the distance (and time necessary) to reach a marked, signalized crosswalk at an intersection.
- Transit plans. Typically, a Complete Streets approach is accompanied by a complementary transit plan. The goal of these transit plans is to shift trip-share away from what is, in most cities, an automobile-dominated environment to a more heavily transit-reliant one.
Beyond this, a core principle is Complete Streets’ attention, shared with Vision Zero, to the safety of road users regardless of mode. But Vision Zero’s focus is strictly on safety, whereas Complete Streets is split between safety and accessibility/multi-modality.
A Complete Streets approach to road design can vary. Figure 1 provides a visual depiction of one type of a complete street.
Complete Streets integrates features such as wider sidewalks, bicycle lanes, crosswalks, accessible pedestrian signals, transit stops, and traffic calming measures. Likewise, it’s also often used to convert existing four-lane streets into two-lane complete streets—though this isn’t the only type of conversion. By considering the needs of different users, Complete Streets aims to improve safety, promote active transportation, and enhance the overall quality of life in communities.
Figure 1: Complete Streets Diagram
Additionally, Complete Streets often employs quick-build projects (alternatively demonstration projects or tactical urbanism projects), which are low-cost, temporary interventions to test street design as was done in Washington State.5 These low-cost interventions allow policymakers and communities to test the impact of proposed changes cheaply before committing to long-term, often more expensive implementation.
Complete Streets approaches also often include complementary transit plans to boost transit ridership. These plans have done little to mitigate the decline in transit ridership nationwide and may require some rethinking for the modern traveling and commuting environment, depending on the needs of each individual city.
Implementing Complete Streets often involves a range of strategies, including road redesign, retrofitting existing streets, adopting zoning regulations that support mixed-use and walkable neighborhoods, and integrating public transportation infrastructure. These efforts are typically guided by community input and data-driven decision-making.
Synergies of Vision Zero and Complete Streets
Both Complete Streets and Vision Zero emphasize safety for users of all transportation modes and favor traffic calming measures and/or lane reconfiguration (by bicycle lanes or sidewalk extensions) as a means of ensuring safety. Complete Streets focuses on the assumption that fewer automobiles on the road means fewer collisions and fatalities. Many Vision Zero activists set a “complete street” as the ideal standard for an urban street because it accommodates multiple modes of transportation (such as bicycles in bicycle lanes and pedestrians on sidewalks) and does so safely.
Additionally, Vision Zero and Complete Streets advocates also promote walkable neighborhoods and more development. These two goals together aid in the natural demand-growth for active transportation. The more densely developed a city is, the easier it is to justify walking from point A to point B, for example.
This brief provides a history of both movements and examines a handful of case studies of relevant city archetypes to attempt to measure the effectiveness of these policies. Most critically, it examines whether or not Vision Zero and Complete Streets policies have been effective at reducing traffic fatalities and explores some potential alternatives.
Full Policy Brief: Vision Zero and Complete Streets: Do They Make Roads Safer?