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Public Roads - Winter 2022

Winter 2022
Issue No:
Vol. 85 No. 4
Publication Number:
Table of Contents

NHTSA’s Safe System Approach: Educating and Protecting All Road Users

by Robert Ritter, Dee Williams, and Gamunu Wijetunge
"A motorist with their hand on the steering wheel views a bicyclist, through the front windshield, walking their bike through a pedestrian crosswalk made of white strips. Photo Source: © ambrozinio / Shutterstock."
NHTSA’s Safe System efforts focusing on safe road users, safe vehicles, and post-crash care.

More than 50 years ago, the Highway Safety Act of 1970 confirmed the commitment of the U.S. Government to work to protect the traveling public’s safety on the road. The legislation established the National Highway Traffic Safety Administration to help reduce the number of deaths, injuries, and economic losses resulting from motor vehicle crashes on the Nation’s highways. The agency’s efforts since then have saved hundreds of thousands of lives—NHTSA estimates that since 1960, improved vehicle safety technologies alone have saved more than 600,000 people. Unfortunately, the Nation continues to lose too many family members, friends, and neighbors to traffic crashes. In 2020, the United States lost more than 38,000 people to traffic crashes.

“We must address the tragic loss of life we saw on the roads in 2020 by taking a transformational and collaborative approach to safety. Everyone—including those who design, operate, build, and use the road system—shares responsibility for road safety, This is the foundation of the safe system approach, and one that guides our lifesaving work at NHTSA,” says Dr. Steven Cliff, NHTSA’s deputy administrator.

The Safe System Approach is a data-driven, holistic, and equitable method to roadway safety that fully integrates the needs of all users, anticipates the possibility of errors by drivers and other road users, and manages crash impact forces to levels tolerated by the human body. The Safe System Approach includes five elements: safe road users, safe vehicles, safe speeds, safe roads, and post-crash care. The approach incorporates the 5 Es of traffic safety—equity, engineering, education, enforcement, and emergency medical services (EMS)—but goes beyond the traditional approach to enlist designers, operators, and users of the transportation system to prevent fatal crashes and reduce crash severity. NHTSA’s efforts focus on safe road users, safe vehicles, safe speeds, and post-crash care.

"Graphic showing a wheel with five sections depicting five Safe System elements: Safe Road Users, Safe Vehicles, Safe Speeds, Safe Roads, and Post-Crash Care. Around the wheel are six Safe System principles: Death/Serious Injury is Unacceptable, Humans Make Mistakes, Humans are Vulnerable, Responsibility is Shared, Safety is Proactive, and Redundancy is Crucial. Image Source: FHWA."
The Safe System Approach principles and elements.

The Safe System Approach broadens NHTSA’s scope with the tenets that safety is proactive and responsibility is shared. It challenges everyone involved to not accept fatalities and serious injuries as a consequence of mobility. Instead, the approach is founded in the conviction that no one should be killed or seriously injured while using the roadway system. It recognizes that people make mistakes, and those who oversee, design, and regulate the components of the transportation system have a responsibility to develop a system that accommodates mistakes. In the case where a crash cannot be prevented, the energy that dictates the injury severity, when possible, should be mitigated to improve survivability outcomes. A Safe System provides equitable, timely, and appropriate care.

Historically, NHTSA has always used a data-driven systems approach to crashes, related causal factors, and candidate countermeasures. The agency’s foundational work is grounded in the Haddon Matrix, introduced by NHTSA’s first Administrator, Dr. William Haddon, in 1969. The Haddon Matrix identifies the factors involved in crashes—from the pre-crash phase, crash phase, and post-crash phase—and how drivers, vehicles, and the environment influence the outcomes of each. The Haddon Matrix embodies the core elements of NHTSA’s historic efforts to reduce traffic injuries and fatalities by using data to identify traffic safety issues and employ countermeasures to target those issues.

NHTSA’s National Center for Statistics and Analysis (NCSA) supports data-driven decisions through the collection and analysis of data and the dissemination of information to quickly identify potential problems and support data-driven safety decisions. In addition to its own data sources, NCSA uses data from other governmental agencies, as well as crash files from States, to support analytical activities. NCSA also regularly publishes a variety of research notes, crash statistics, traffic safety fact sheets, and reports that provide information on crashes at the national and State levels (for more information, please see 

"Table showing the National Highway Traffic Safety Administration’s Haddon Matrix. 4 columns and 4 rows. The columns are “Factor,” “Pre-Crash,” “Crash,” and “Post-Crash.” Row 1: The “Human Factors” factor corresponds to these Pre-Crash examples: Education & licensing, Driver impairment, and Crash avoidance maneuvers (braking, turning, etc.); to these Crash examples: Health at time of crash, Sitting properly in restraint, and Impairment; and these Post-Crash examples: Response to emergency medical services, Severity of injury, and Type of injury. Row 2: The “Vehicle/Equipment Factors” factor corresponds to these Pre-Crash examples: Crash avoidance equipment and technology (lights, tires, collision avoidance, etc.), Vehicle design, and Vehicle load; to these Crash examples: Speed of travel, Functioning of safety equipment (seat belts, air bags, child restraints), Energy absorption of vehicle; and these Post-Crash examples: Ease of extraction from vehicle, Integrity of fuel systems and battery systems. Row 3: The “Physical Environment” factor corresponds to these Pre-Crash examples: Road hazards, Distractions, and Weather conditions; to these Crash examples: Roadside features, Guardrails, and Type and size of object struck; and these Post-Crash examples: Distance of emergency medical services clinicians, Notification of emergency medical services clinicians, and Accessibility to crash victims. Row 4: The “Social/Economic” factor corresponds to these Pre-Crash examples: Enforcement activities, Insurance incentives, Social norming, and Ability to use safety equipment appropriately; to these Crash example: Laws concerning use of safety equipment; and these Post-Crash examples: Trauma system equipment, personnel, training, and Information sharing. Table Source: NHTSA."
NHTSA’s Haddon Matrix identifies the factors involved in crashes and provides examples of safety efforts that can influence the outcomes.

Safe Road Users 

The Safe System Approach targets the safety of all road users, including those who walk, bike, drive, ride transit, and travel by other modes. All road users should have the opportunity to travel safely, regardless of how they travel. At the same time, road users have a responsibility to operate, to the best of their ability, within the expectations and boundaries of the transportation system. NHTSA works with stakeholders—road users as well as local, State, and private partners—to help them understand their responsibilities in a Safe System. Everyone shares ownership of the road system and all share responsibility for maintaining a Safe System.

Education and training on safe road behaviors comprise the cornerstones of promoting safe road users. NHTSA works to reinforce positive behaviors (such as reminding motorcyclists to use proper safety gear and vehicle occupants to use proper adult and child restraints) and to deter dangerous behaviors (including impaired, distracted, or drowsy driving).

NHTSA develops research-based programs and safety campaigns that educate road users to drive sober, wear seatbelts, be attentive, and move at safe speeds. For example, NHTSA creates and places social, digital, and traditional media advertisements to encourage all parents and caregivers to use the correct car seat for their child’s age and weight.

"A woman buckles a small child into a child safety seat with properly fitted restraints. Photo Source: NHTSA."
NHTSA offers resources to educate and train road users on safe behaviors and equipment, including campaigns using the correct child safety seat for a child’s age and weight.

NHTSA raises awareness of the dangers to pedestrians by providing safety tips for walkers of all ages, educational material, statistics, resources including information for drivers on avoiding pedestrians, and conducting public campaigns, such as Everyone is a Pedestrian. Further, NHTSA has developed resources to help States and local communities identify, address, and improve pedestrian safety, including a data visualization tool, safety tips, and social media graphics and messaging. Additionally, NHTSA places special emphasis on people who walk throughout the month of October which is designated as National Pedestrian Safety Month. Everyone has a role to play and must work together to keep all road users especially our most vulnerable ones safe.

"A woman and a child cross at a striped crosswalk while a car waits. Photo Source: NHTSA."
October is National Pedestrian Safety Month, and NHTSA and its partners run awareness campaigns to emphasize that all road users have a role in keeping pedestrians safe.

The Buckle Up. Every Trip. Every Time. campaign reminds road users that wearing a seat belt is one of the most powerful choices drivers and passengers can make to ensure their safety while in a vehicle. Proper seat belt use means other elements of the Safe System—safe vehicles and post-crash care—can work together to reduce fatalities and serious injuries.

"Campaign logo that reads: Buckle Up. Every Trip. Every Time. Image Source: NHTSA."

Other examples of NHTSA efforts to educate road users include reminding motorcyclists to make themselves visible, to use motorcycle helmets that are compliant with U.S. Department of Transportation regulations, and to always ride sober. NHTSA helps older road users understand how aging and associated medical conditions can affect driving in addition to adapting a vehicle to meet changing physical needs. On the other end of the age spectrum, NHTSA provides information on States’ driver licensing requirements for novice drivers and promotes a three-stage graduated driver licensing system and training for new drivers so that they understand how to safely navigate the built environment with other users.

Fair and equitable law enforcement is an important component in the Safe System Approach—not only to prevent a crash (supporting voluntary compliance with State laws) and to respond when a crash happens (providing emergency care, ensuring safety of other road users, and expediting scene clearance), but also as part of the shared responsibility to provide feedback to improve the system design and operation based on officers’ experience in responding to crashes. Law enforcement officers also serve as educators on the frontline to help remind all road users—drivers, pedestrians, bicyclists, transit riders, and others—to use the transportation system safely.

High visibility enforcement and education campaigns have been successful strategies for many decades at NHTSA, while supporting the Safe System Approach principles that safety is proactive and that responsibility is shared. The “Click It or Ticket” seat belt and “Drive Sober or Get Pulled Over” impaired driving campaigns are recognized by most licensed drivers. Currently, NHTSA is working to reduce distracted driving with the “U Drive. U Text. U Pay.” campaign. Impaired driving laws and the enforcement and consequences of these laws have worked together to reduce the number of impaired driving fatalities by half since the early 1980s.

To support its education and enforcement efforts, NHTSA has created effective partnerships with community and safety stakeholders to include health professionals, parents, community organizations, law enforcement, members of the justice system, and nonprofit organizations.

"Logo for the “Drive Sober or Get Pulled Over” campaign. Image Source: NHTSA."

Safe Vehicles 

The vehicle—be it a car, sport utility vehicle, pickup truck, heavy truck, transit bus, or other type—is an important component of a Safe System. Recent technological advances in the automotive industry provide a variety of tools to enhance roadway safety through this element of the system. Technology provides a key opportunity to address the Safe System tenet that humans make mistakes by supporting drivers where they may err and mitigate some of the outcomes that could result from unsafe behaviors. These systems, when properly used, can substantially reduce crashes. For example, automatic emergency braking system technologies are specifically designed to help drivers avoid, or mitigate the severity of, rear-end crashes. In 2019, almost one-third of all police-reported crashes involved a rear-end collision with another vehicle at the start of the crash. For more information, please see NHTSA’s Annual Traffic Safety Facts at

Another essential aspect of a safe vehicle is crashworthiness—how well a vehicle protects its occupants in a crash. NHTSA’s aim is to make vehicles as safe as possible or their crashworthiness as great as possible by affording injury protection to occupants when a crash occurs. NHTSA also focuses on addressing the safety of those vulnerable road user populations outside or around the vehicle to minimize impact or severity of injury through data collection, research, and leveraging of new technologies. NHTSA efforts on vehicle crashworthiness have focused on new and improved vehicle design; biomechanics and injury causation; field data collection; and analysis of serious injury cases, safety countermeasures, and equipment to enhance occupant safety. Despite modern vehicles being safer than ever, the need remains to improve the understanding of injury causation through the development and upgrade of test procedures for the evaluation of motor vehicle safety, the development of crash test dummies and human body computer models, and appropriate injury metrics.

"Two animated test dummies shown crashed through the windshield of a test car in a safety campaign image. Photo Source: NHTSA."
NHTSA’s famous test dummies Vince and Larry star in commercials and educational campaigns to warn drivers to buckle up.
"An advanced crash test dummy. Photo Source: NHTSA."
NHTSA is developing the THOR (Test device for Human Occupant Restraint) crash dummy; the alpha model is shown here. These advanced dummies have more humanlike response throughout the body as well as advancements in instrumentation that will help assess more advanced restraint systems.

NHTSA uses a family of crash test dummies to help the agency understand and measure the human body’s movement, vehicle performance, and the performance of various safety features during a crash. Measurements from the test dummies predict the risk of injury to each part of the body during air bag deployment and in crashes involving frontal, side, and rear impacts. NHTSA has dummies that differ in size, weight, and movement to account for some of the variations in body types, as well as crash circumstances.

NHTSA’s family of dummies ranges from newborns to 10-year-old children to small females and average males. NHTSA is also involved in worldwide development and evaluation of crash test dummies even more advanced than those used today. Design, instrumentation, and testing with these crash test dummies help ensure the safety of vehicle occupants in the unfortunate event that a crash occurs by encouraging safety improvements to vehicles to provide better vehicle crashworthiness through occupant protection—saving lives. Technologies that improve crashworthiness and afford protection to the users include seat belts, advanced air bags, and electronic stability control.

While protecting occupants and vulnerable road users in a crash is important, the most desirable outcome would be to prevent crashes from happening whenever possible: no crash, no injuries, no fatalities. Advancements in technology have added a new dimension to the vehicle safety space. Active safety systems, which are types of advanced driver assistance systems (ADAS), proactively anticipate and assist drivers who may not respond to immediate and/or imminent dangers around them. These technologies include automatic emergency braking system technologies and electronic stability control—both referred to as active safety systems—to provide momentary intervention during potentially hazardous situations.

"Curved lines emit from a single car on a road with white lines. Photo Source: NHTSA."
Active safety systems like automatic emergency braking technology can assist drivers and prevent crashes.

There are a variety of other passive ADAS technologies available in the marketplace now. Passive ADAS technologies alert drivers of potential risk situations to give the driver time to respond. Some examples of these systems include forward collision warning, which detects a potential collision with a vehicle ahead and alerts the driver (some systems also provide alerts for pedestrians or other objects); lane departure warning, which monitors a vehicle’s position within the driving lane and alerts the driver as the vehicle approaches or crosses lane markers; and blind spot warning, which detects vehicles in the blind spot while driving and notifies the driver to their presence (some systems provide an additional warning if the driver activates the turn signal). Note that these systems only provide a warning to the driver and do not take action to avoid a crash.

The benefits of these various active and passive safety systems are well documented in helping drivers avoid or mitigate crashes, but they can only address a portion of related crash circumstances. It is vital to emphasize that drivers will continue to share driving responsibilities for the foreseeable future and must remain engaged and attentive to the driving task and the road ahead.

Newer vehicle innovations under testing and development, such as Automated Driving Systems that at maturity contemplate replacing human drivers, also follow the Safe System principles and involve all stakeholders early and often, as an opportunity to contribute to the Safe System Approach.

Post-Crash Care 

Even with improvements in all components of the Safe System Approach—roads, vehicles, and road users—traffic crashes still happen. A comprehensive and integrated post-crash care system can further reduce fatalities and serious injuries resulting from those crashes. 911 emergency communications centers, first responders and highly trained EMS personnel, emergency departments, and trauma centers are all essential parts of that system.

The actions taken after a crash are vital to reducing death and disability. Improvements to EMS systems, such as automated communication of crash location and severity, may reduce the 40 percent of deaths from traffic crashes that occur after the arrival of EMS at the crash scene. The information collected by 911 telecommunicators and EMS clinicians also serves as a robust resource for examining the factors that influence traffic crashes and patient outcomes.

NHTSA has integrated post-crash considerations in its work since the very beginning. NHTSA’s Office of Emergency Medical Services was part of the group of EMS stakeholders that developed standard curricula for EMS clinicians, the National EMS Information System (NEMSIS), and evidence-based guidelines for prehospital care. NHTSA also maintains and, which serve to educate and inform the general public, EMS, and 911 stakeholders about critical issues.

Today, NHTSA continues to collaborate with partners to advance post-crash care. A key component of post-crash care is the National EMS Education Standards. The standards support consistency in EMS care across the country. NHTSA also funds the development of several evidence-based guidelines for clinical care, including guidelines for bleeding control, pain management, and the appropriate triage of trauma victims to ensure that the right patients get to the right hospital at the right time.

The NEMSIS establishes a common data standard used by EMS systems throughout the country. When EMS clinicians respond to a 911 call and treat a patient, they complete an electronic patient care report that uses the NEMSIS standard. This common NEMSIS language enables information to be easily combined for surveillance, analysis, and research. The National EMS Database collects NEMSIS data—via State repositories—in near real time. In 2020, EMS systems in 50 States and territories submitted more than 43 million EMS records. The National EMS Database can provide information on nearly every 911 activation for a medical emergency or injury, making it a powerful tool for studying everything from the COVID-19 pandemic to pedestrian injuries to vehicle crashes.

NHTSA also houses the National 911 Program, which supports the advancement of 911 systems across the country. The program works with stakeholders to ensure a smooth transition to an updated 911 system to leverage new technologies. The program also administers a 911 Grant Program, which has awarded more than $100 million to States and Tribal nations.

"Emergency medical personnel place a woman on a stretcher. Photo Source: NHTSA."
Post-crash care, including the sharing of information like crash location and injury severity with responding emergency personnel, is critical to improving patient outcomes.

In Conclusion 

“NHTSA believes in an approach that is people-focused, meaning that infrastructure serves the needs of its users, not the other way around. As we continue to move forward [with] a Safe System Approach, we will not forget the voices of those who use the roads, particularly those in communities of color, underrepresented communities, and people with disabilities. A successful Safe System Approach respects all users,” Dr. Cliff says.

All system managers, owners, designers, and users need to be actively involved in advancing and preserving the safety of the system. Everyone plays a role—from community and advocacy organizations to public safety officials and transportation experts, road users, vehicle designers and developers, law enforcement, and first responders. Building a Safe System requires an extraordinary commitment to community engagement. System users need to be involved in decisions before building the road system, in education on how to use it, and in reinforcing public trust that the system will be safe for users when everyone shares responsibility for it. And, most important, when assessing Safe System decisions, NHTSA will integrate the input and needs of all road users—not just drivers and passengers but pedestrians, cyclists, children, older Americans, and people with disabilities—as the Nation moves forward.

Robert Ritter is the director of the Office of Impaired Driving and Occupant Protection at NHTSA, where he works to reduce the incidents of alcohol and drug-impaired driving, increase seat belt and child safety seat use, and reduce distracted and drowsy driving. He is a licensed civil engineer and holds a master’s degree in transportation from Morgan State University and bachelor’s degrees in civil engineering from Rutgers University School of Engineering and in religion from Rutgers College (now part of the Rutgers University School of Arts and Sciences).

Dee Williams is the deputy associate administrator for NHTSA’s Office of Vehicle Safety Research. She leads the development of vehicle safety research and policy initiatives to advance national highway traffic safety programs, innovative technologies, and motor vehicle safety standards. She holds a B.A. in political science from Susquehanna University.

Gamunu Wijetunge has served as an EMS specialist within the Office of EMS at NHTSA since 2001. His main responsibilities include disaster preparedness, air medical issues, the EMS workforce, and development of clinical evidence-based guidelines. An active paramedic and firefighter, he holds a B.S. in emergency health services from the University of Maryland, Baltimore County and a master’s degree in public management from the University of Maryland, College Park. He would like to thank Michael Gerber for his contributions to this article.