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Safe Systems in the U.S. – Finding a Path for Road Designers and Transportation Planners and Engineers


In 2001, the “Geometric Design Practices for European Roads” scan tour report indicated that the U.S. delegation found potentially transferable practices regarding public involvement in project planning; self-explaining, self-enforcing rural roads; design flexibility; area-wide traffic calming measures; intersection control through roundabouts; and integration of bicyclists and pedestrians. Many of these concepts have been shared across countries and the underlying philosophy is commonly called a “safe systems” approach.

“Safe Systems” has been defined in various ways in the transportation profession as a whole, even in the more focused transportation safety community. Sweden was one of the first adopters of a Safe Systems approach with its Vision Zero program. The Safe Road Transport System Model and the safe system definition were presented by the Organization for Economic Co-operation and Development’s (OECD) International Transport Forum in 2008 as: “The basic strategy of a Safe System approach is to ensure that in the event of a crash, the impact energies remain below the threshold likely to produce either death or serious injury.” This definition acknowledges road users make mistakes even though for the most part, they act rationally. In the model, safe speeds represent the primary pathway towards a safer system, and it further includes: 1) safe vehicles; 2) safe roads; and 3) safe road users. The SUN countries, Sweden, the United Kingdom and Norway, based their improvements in road safety at least in part on the Safe Road Transport System model and Australia attributes its successes to the safe system approach. These countries have outpaced the United States in driving down traffic related deaths and are arguably “safer” than the U.S. (Marshall, 2017.)

In the United States, The Road to Zero and Vision Zero national initiatives promote “Safe System” principles as the preferred path to reducing traffic fatalities in the United States. Towards Zero Deaths (TZD) includes some of the Safe System strategies through traditional and innovative approaches including multi-disciplinary implementation that includes safer roads, vehicles, road users as well as safety culture. The Vision Zero Network in particular has been aggressive about including safe system principles, most specifically speed reduction, in its work with the more than 30 local communities that have committed to Vision Zero since 2014. According to Vision Zero proponents, in spite of “increased interest, little guidance exists for local transportation planners, policy makers, public health practitioners, police and others working” to advance the U.S. Vision Zero and its safe systems approach (Fleisher, Wier, and Hunter, 2016.) The same may be said for guidance to the state and national engineering, design, and planning communities. Professionals in the road planning, design and engineering community are faced with legacy design processes and standards as well as legal constraints which prohibit rapid adoption of a more aggressive approach to implementing some of the hallmarks of Safe Systems. Many of the Safe Systems design and operational concepts require a shift in the culture and approach to roadway use and design including the increased consideration of all road users.

OECD stressed in the 2008 report that a Safe Systems approach is “the only way to achieve the vision of zero road fatalities and serious injuries and it requires that the road system be designed to expect and accommodate human error.” It continues that a Safe System approach is appropriate for countries at all levels of road safety performance, with specific interventions likely to differ from country to country. The tension to operationalize Safe Systems approaches for use in the project delivery processes for all projects, as well as safety countermeasure application specifically is heightened by the undisputed and alarming increasing in traffic related fatalities in the past several years. Indeed, after years of decreases the number of deaths has risen from 32,744 in 2014 to 37,461 in 2017 (NHTSA, 2018.)

Transportation safety is a complex issue and a true safe system approach must address many factors to be successful and must be adaptable in anticipation of future change (e.g. autonomous and connected vehicles). At a minimum these include the role of the road user in behaving properly, vehicle design, policy and laws, public and organizational and public cultures, etc. For Safe Systems to be fully implemented, all of these will have to change. This synthesis is proposed as a starting point to provide practical and effective information for the engineering, design, and planning communities to consult during project development and countermeasure selection processes.


A discussion among transportation professionals in the United States revealed that there is no clear understanding of the “Safe Systems” approach. The purpose of this proposed research provide practitioners a clearer picture of what a “Safe Systems” approach would involve. This research is focused on providing data based support to the transportation engineering, design, and planning communities to ensure when road users make inevitable mistakes, they encounter “error tolerance” (Johansson, 2008) and as a result of their mistakes do not experience serious injury or death. The proposed research should also be forward thinking when evaluating current approaches in anticipation of technological advances. The scope includes the task to identify opportunities for the road design, planning, and engineering communities in the U.S. and abroad to accelerate implementation of appropriate safe system infrastructure and Human Factors interventions and countermeasures by identifying available tools and gaps in guidance.

To help agencies achieve the Road to Zero goal of zero deaths and serious injuries in the United States by 2050, agencies will need to modify their processes for completing roadway projects. This research supports the AASHTO Strategic Plan for the Committee on Safety Goal 1, Strategy 1.1, “Lead in the Implementation of Toward Zero Deaths: A National Strategy on Highway Safety. In an ideal world, any project concept would include elements related to context, evaluation of operations, safety, human factors, and public health as part of a safe transportation system. Each iteration of the project from planning through final design would depend on this multiple lens approach. The following questions will be investigated as related to a Safe Systems approach.

  1. What is a Safe Systems approach in the context of developing a transportation project and how does it differ from the current project development process?

  2. What kinds of plans and planning processes do the Safe Systems countries use?

  3. How can the U.S. planning process more effectively implement a Safe Systems approach?

  4. How would a Safe Systems approach look in the future with technological advances such as autonomous/connected vehicles, transportation-as-a-service, or micromobility?

  5. What are the differences in various contexts (e.g. urban core, general urban, suburban, rural, etc.)?

  6. What is the approach to design standards prevalent in countries that have adopted a Safe Systems approach such as Sweden and Norway and can they be mapped to current U.S. standards particularly in regard to speed management and other key Safe System components or is a new approach recommended?

  7. What are the guidelines and policy constraints on roadway designers and operators in Sweden or other European counties and Australia?

  8. What exists today in the way of tools that result in a Safe Systems approach in the U.S.? Consider major design guides, NACTO, new and alternate guidelines, context sensitive solutions, Human Factors, etc.

  9. What gaps exist?

  10. What tools are needed in the various processes including concept, planning, data, analysis, design, and construction?

  11. How do the Human Factors, Safety Culture, and Public Health sectors fit in with the Safe Systems approach?

  12. What public agency policies may need to be changed/modified?

  13. What legal challenges exist in the U.S. that would have to be addressed prior to changing the approach?

  14. What are the research needs associated with a transition?

  15. What is the effect of a Safe Systems approach on freight transit and economic development?

  16. What role does mass public transit play in a Safe Systems approach?


This research will result in a report that provides an overview of available U.S. and international guidelines to implement Safe Systems well as a description of how these can be currently utilized in the project development and delivery process at DOTs and other transportation agencies. As important, gaps for additional tools will be identified and future research suggested.

Related Research:

University of North Carolina (UNC) Highway Safety Research Center - Safe Systems Synthesis: An International Scan for Domestic Application (June 2018) conducted a literature and policy scan of international practices associated with Safe Systems. UNC also has an ongoing project – Defining Safe Systems: A Review of the state-of-the-Practice and Leadership Summit. This project will develop a single, working definition of the “safe systems” concept. A second activity is to host a safe systems summit. The proposed research will build off these earlier research efforts.


At a minimum, implementation of this study will require:

  • State transportation departments will need broad recommendations on next steps including future research and data needs;

  • Outreach materials and widespread publication of results for transportation professionals;

  • Alternative pathway projections based on potential investment;

  • Reasonable time-based goals and performance measures for successful implementation (% of fatality reduction, % of infrastructure updated, etc)

Sponsoring Committee:ACS10, Transportation Safety Management Systems
Research Period:12 - 24 months
Research Priority:High
RNS Developer:Dan Magri, Chad Winchester, Marie Walsh, Adriane McRae, Jessica DeVille
Source Info:Dan Magri, Deputy Assistant Secretary, Office of Planning, LA DOTD
Chad Winchester, Project Development Division Chief, LA DOTD
Marie Walsh, Louisiana LTAP Director
Adriane McRae, Highway Safety Administrator, LA DOTD
Jessica DeVille, Highway Safety Engineer, LA DOTD
Date Posted:04/04/2019
Date Modified:05/17/2019
Index Terms:Highway safety, Highway design, Highway planning, Europe, Safety management,
Cosponsoring Committees: 
Planning and Forecasting
Safety and Human Factors

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