The Safe Systems approach differs from conventional safety practice by being human-centered, i.e. seeking safety through a more aggressive use of vehicle or roadway design and operational changes rather than relying primarily on behavioral changes – and by fully integrating the needs of all users (pedestrians, bicyclists, older, younger, disabled, etc.) of the transportation system. Safe Systems provide a safety-net for the user by:
1. Anticipating Human Error – Safe Systems are designed to anticipate and accommodate errors by drivers and other road users.
Example: Even a momentary distraction can prevent a driver from seeing vulnerable road users or vice-versa. Separating vulnerable road users, such as pedestrians and bicyclists, from traffic wherever possible reduces the likelihood that such predictable errors will lead to a deadly collision.
Example: On rural highways the application of rumble strips can recapture the driver’s attention when they drift out of the lane due to distraction or fatigue. In newer vehicles, lane-keeping technologies can provide similar benefit.
2. Accommodating Human Injury Tolerance – Safe Systems are designed to reduce or eliminate opportunities for crashes resulting in forces beyond human endurance.
Example: Where pedestrians and vehicles need to occupy the same space – such as urban crosswalks – reducing vehicle speeds through the use of lower speed limits combined with road design changes can reduce the likelihood of fatal collisions with pedestrians or bicyclists.
Example: Breakaway designs on traffic control devices installed in the right-of-way can reduce the force of impact when struck by an errant vehicle.
When we take a Safe Systems approach we may employ some of our current safety practices, but by taking a human-centered approach we will often make different decisions than we would have otherwise.
The goal of a Safe Systems approach is to design and operate our vehicles and infrastructure in a manner that anticipates human error and accommodates human injury tolerances with a goal of reducing fatal and serious injuries. The following framework is intended to assist the vehicle and infrastructure communities in making decisions in alignment with Safe Systems principles. Consistently selecting safe system designs will incrementally improve safety and over time result in the widespread implementation of safe system practices.
Creating Safe Systems will involve both traditional and new approaches. We must embrace and expand the use of Safe Systems practices that we know work, while being willing to try and evaluate new or non-traditional approaches, particularly when it comes to protecting vulnerable users.
Adopting a Safe Systems approach necessarily means adopting a safety culture. Steady progress can be made by putting safety first and following Safe Systems principles in each of the large and small decisions that confront us every day.
Adopting a Safe Systems approach does not absolve users of responsibility. Programs such as education and enforcement will remain essential. Providing effective emergency response when crashes do occur is also a critical element of Safe Systems. However, safe system design choices recognize that road users make mistakes or bad decisions and seeks to reduce the opportunities to do so or mitigate the consequences.
Reducing speed is not a direct prerequisite of Safe Systems, but will sometimes be necessary to achieve alignment with Safe Systems principles. In locations where vehicles interact with vulnerable road users, speeds should be controlled to a level at which a collision is unlikely to result in a fatal or serious injury.
When we choose a Safe Systems approach, we must accept that doing so may result a decrease in vehicle throughput and may limit the range of behavioral choices for users. However, such decisions are part of responsible system stewardship. As transportation professionals we have a moral obligation to protect lives while creating a reliable transportation system.
I. Anticipating Human Error
Recognizing that humans are human and that they will continue to make errors when traveling, one way to implement a Safe Systems strategy is to reduce the opportunity for error by:
Note: Sometimes a combination of both techniques is used, such as a protected left turn bay where the turning vehicles are physically separated while awaiting the opportunity to turn and separated in time through the use of a protected left turn phase.
II. Accommodating Human Injury Tolerance
The laws of physics dictate that greater harm will occur at higher speeds and that, typically, the greater the mass of a vehicle, the more harm that it will inflict on others.
Sustainable and Safe: A Vision and Guidance for Zero Road Deaths
A report from World Resources Institute published in January 2018 highlights systemic approach that shifts responsibility away from the drivers and pedestrians using the roads to the city planners and officials designing them. This report is international and could be applied in the US since it is not written toward a specific roadway system. The report is available for download: https://www.wri.org/publication/sustainable-and-safe-vision-and-guidance-zero-road-deaths.
Speed management: a road safety manual for decision-makers and practitioners.
The World Health Organization Speed Management Manual highlights the Safe Systems approach to speeds starting on page 14 of the Manual. This is an international focused document with elements that could be applied to Safe Systems in the US as it is not written toward one countries roadway system.
Road Safety Manual: A Manual for Practitioners and Decision Makers on Implementing Safe System Infrastructure
The World Road Association Road Safety Manual is wholly written around Safe Systems as a means for road safety and the manual also provides as specific section on how to apply Safe Systems. The Safe Systems section of the Road Safety Manual covers topics of crash causes, responsibilities, principles, elements and implementation with an international focus but some topics could also be considered for application in the US as we shift our system toward Safe Systems.
Speeding - Did you know? Fact Sheet
The New South Wales Centre for Road Safety has a short fact sheet on Safe Systems, the key to managing road safety that provides an overview of Safe Systems principles that may be applied in the US from countries like Australia, the Netherlands and Sweden.
Toward Zero: Ambitious Road Safety Targets and the Safe Systems Approach
The Transport Research Centre also has an internationally focused report titled “Toward Zero: Ambitious Road Safety Targets and the Safe Systems Approach” which highlights Safe Systems as a means to eliminate road fatalities, but also specifically gets in to Safe Systems approaches on pages 107 through 133 as a context for developing interventions, Safe Systems implementation tools, and performance measures to gauge improvement.
How would a Safe Systems approach to road safety work in the U.S.?
The Collaborative Sciences Center for Road Safety has an evolving web page on “How would a Safe Systems approach to road safety work in the U.S.?” with an overview and numerous resources from reports to articles. Most of the resources featured are about general systems based thinking, but some resources are geared toward transportation systems. The page can be found: https://www.roadsafety.unc.edu/about/safesystems/.
A report titled “Implementing Safe Systems in the United States: Guiding Principles and Lessons from International Practice” published by CSCRS in June of 2019. This report identifies Safe Systems elements and principles from countries that have improved safety through the application of Safe Systems.
Another report titled “Safe Systems Synthesis: an International Scan for Domestic Application” published by HSRC in late June of 2019 provides an overview of numerous successful international approaches internationally and may apply in the US. Starting on page 31, the synthesis outlines five Safe Systems trends and three concerns to applying Safe Systems in the US.
Webinars on Safe Systems
ITE Introduction to Safe Systems webinar provides a summary of a US Safe Systems Explanation, Framework and provides a connection between US fatal crashes, roadway design and vehicle design.
ITE Safe Systems and Speed Management webinar outlines the need for speed management to achieve Safe Systems and how US cities are thinking about a Safe Systems approach in speed management work.
Vision Zero Network webinars on Safe Systems
National Center for Rural Road Safety Safe Systems for Rural Users webinar.
Shorter Articles on Safe Systems