CHAPTER 6

Safe System Law Enforcement

Law enforcement plays a pivotal role in fostering a Safe System. As users of the network and often being the first to respond to incidents, law enforcement officers see firsthand the potential for road-user injury. Additionally, they are responsible for enforcing the rules of the road and encouraging safe road-user behavior. Coordination among law enforcement personnel, planners, designers, and policymakers can result in proactively addressing officer-observed injury risks. Furthermore, penalizing transgressors of roadway laws can discourage unsafe behaviors.

The current law enforcement regime is rooted in the deterrence theory, which relies on the certainty, swiftness, and severity of punishments to be effective (Paternoster 2018; Barnum and Nagin 2023). Indeed, legal threats are most effective when potential rule violators perceive a high likelihood of being caught committing an unlawful act, believe the resulting punishment will be severe, and understand that the punishment will be applied quickly after the offense (Davey and Freeman 2011). Among these factors, certainty appears to be the most powerful deterrent to performing risky or unlawful behavior (Von Hirsch 1999; Truelove et al. 2017).

Unfortunately, violating traffic laws is commonplace, especially when it comes to driving above the posted speed limit. The AAA Foundation for Traffic Safety’s 2022 Traffic Safety Culture Index study found that 40 percent of drivers stated they had exceeded the posted speed limit by 15 mph on a freeway in the past month, and nearly 30 percent reported exceeding the speed limit by 10 mph on a residential street (AAA Foundation for Traffic Safety 2023). However, more than 80 percent of respondents perceived this level of speeding to be moderately to extremely dangerous. Yet, 37 percent of respondents believed it was unlikely a driver would be caught by police for driving 15 mph over the speed limit on a freeway, and 51 percent of respondents believed drivers would not be caught by police for driving 10 mph over the speed limit on a residential street. These statistics suggest there is a perceived sense of danger with speeding; however, drivers are not deterred from this behavior perhaps because they do not perceive punishment as certain.

The events of May 2020 (the killing of George Floyd in Minneapolis, Minnesota, and uprising of the Black Lives Matter movement) reshaped how law enforcement officers interact with their communities and enforce the laws. These events coupled with reallocation of police funding has decreased the resources available to enforce basic traffic laws. According to the Police Executive Research Forum (PERF), 182 law enforcement agencies across the country noted a nearly 5 percent decline in sworn officers between January 2020 and January 2023 (PERF 2023). Fewer law enforcement staff has resulted in added challenges in implementing the Safe System approach through traffic law enforcement in isolation. Therefore, coordination with transportation professionals is critical.

Beyond ensuring certain punishment for traffic law violations, a Safe System–aligned law enforcement paradigm can contribute to cultural shifts, ones that lead to perceiving safe road-using behaviors as possible, desirable, and normal (Daugbjerg and Kay 2020). A paradigm shift

Another example of a protective policy is the use of speed governors or ISA technology. An investigation into a crash resulting in nine fatalities in 2022 led the National Transportation Safety Board (NTSB) to recommend ISA in all new vehicles. The crash was determined to be caused by excessive speed, drug-impaired driving, and the failure to deter habitual speeding despite the driver having numerous recorded speeding citations (NTSB 2023). ISA would use a vehicle’s Global Positioning System location, a database of posted speed limits, and an onboard camera to help ensure safe and legal speeds. Active systems would warn a driver through visual, sound, or haptic alerts when the vehicle exceeds the posted speed limit, but the driver is responsible for controlling the speed. Passive systems physically limit the speed at which the vehicle can travel. Both systems are examples of protective policy systems that could be employed, especially for habitual speed violators, to promote safer speeds.

Observe, Document, and Share Risk Patterns with Road Designers and Planners

A real potential for change comes with law enforcement personnel observing, documenting, and sharing risk patterns with road designers and planners rather than conducting isolated enforcement operations (Blank, Sandt, and O’Brien 2020). Law enforcement officers use the roadway network regularly and often know where the riskiest behaviors occur. Drivers may be more likely to travel at high speed along multilane roadway segments. Pedestrians may regularly cross outside of crosswalks near schools or businesses because of the lack of nearby crossing facilities (as seen in Figure 14). This information can be shared with roadway designers and planners so that infrastructure improvements may be considered to address riskier behaviors and minimize the need for persistent law enforcement intervention. Most commonly, these observations are noted as part of road safety audits when law enforcement officers collaborate with other safety professionals to assess the safety performance of a roadway or intersection. However, the communication of these observations should not be reserved only for official audits. Rather, open communication and collaboration with roadway designers and planners can occur on a regular basis, either as patterns are noted by law enforcement or through scheduled coordination meetings with road designers and planners.

Photo courtesy of Burgess & Niple.

6.2 Study-Identified Law Enforcement Practices

Stemming from these law enforcement strategies are more specific safety practices. To identify Safe System–aligned practices, the team extracted 11 of them from the literature review phase of the research and presented them to safety practitioners via an online survey (see Appendix E). Survey participants were asked to rate the financial, social, and political feasibility of each practice and the safety impact based on their professional experience and institutional knowledge. Analysis of the responses revealed a modest range of feasibility scores and a wide range of impact scores, which can be found in Appendix E.

In coordination with Safe System principles and law enforcement strategies, the team determined whether each law enforcement practice would reduce road users’ exposure to severe crash types (e.g., run-off-road, head-on, intersection, pedestrian, bicyclist, or motorcyclist crashes) and the likelihood road users would be involved in one or more of these crash types.

• Exposure reflects the number of people with the potential to be involved in serious crash types.
• Likelihood reflects the probability road users will be involved in a crash.
• Severity reflects the chances a crash will result in a fatality or serious injury to the road users involved.
• Improves injury risk assessment, professional and community coordination, or crash diagnoses reflects a practice’s ability to estimate road-user injury risks associated with land use, policy, or engineering interventions; to improve coordination among professionals in different sectors and with the public; or to uncover contributing factors to serious crash events.

Table 10 provides example law enforcement practices and their change mechanisms (i.e., the steps or processes responsible for improving road users’ safety).

Implementing Safe System Law Enforcement Practices

Safe System law enforcement strategies and practices advance coordination with other professional disciplines to investigate serious crashes; enforce road-user protective policies; and share observed risk patterns with planners, engineers, and policymakers.

To begin implementing Safe System–aligned law enforcement practices, consider following these steps and substeps:

1. Identify at least one significant safety problem. Identification and prioritization of a safety problem might be based on the following:
   • – Severity and magnitude of the safety problem
   • – Disproportionate harm endured by some community members by the problem
   • – Importance of addressing the problem to community representatives
   • – Availability of resources to address the problem
2. Once a safety problem has been identified and prioritized, ask the following two questions:
   • –To what extent does a proposed practice to address the identified problem align with Safe System–aligned law enforcement strategies?
     • Work collaboratively to investigate serious crashes and share contextual insights
     • Enforce road-user protective policies
     • Observe, document, and share risk patterns with road designers and planners
   • – To what extent does a proposed practice address the following?
     • Users’ exposure to serious crashes
     • Likelihood of serious crashes
     • Severity of crashes when they occur
     • Improvements to injury risk assessment, professional and community coordination, or crash diagnoses

Table 10. Safe System law enforcement practices.

Example Practice	How Safety Is Improved	Exposure	Likelihood	Severity	Improves IRA, PCC, or CD1	Costs2
Instituting immediate administrative license revocation or suspension (ALR/ALS) for alcohol- and drug-impaired-driving offenses	Discourages impaired driving with swift and severe punishment			−	−	Medium
Instituting or enforcing a statewide primary enforcement seatbelt-use law, which would require occupants to wear seatbelts in both the front and back seats and allow law enforcement officers to ticket occupants for not wearing a seatbelt, without other citable traffic infractions taking place	Promotes seatbelt usage so that in the event of a crash, the outcome may be less severe	−	−		−	Medium
Instituting high-visibility saturation patrols for alcohol- or drug-impaired driving	Increases the certainty of offenders being caught for driving impaired and can remove impaired drivers from the road			−	−	Medium
Requiring alcohol ignition interlocks installed for all drivers convicted of driving under the influence (DUI)	Lowers the potential for DUI offenders to drive impaired without police intervention			−	−	Medium
Instituting or enforcing a statewide universal motorcycle helmet law, which would require all motorcyclists to wear U.S. DOT–compliant helmets, regardless of the rider’s age or experience	Promotes helmet usage so that in the event of a crash, the outcome may be less severe	−	−		−	Medium
Reframing the context of a crash (i.e., not victim-blaming, not calling the incident an accident) when engaging news media partners	Changes the narrative around crashes and supports the notion that crashes are preventable, even when humans make mistakes	−	−	−		Low

Example Practice	How Safety Is Improved	Exposure	Likelihood	Severity	Improves IRA, PCC, or CD1	Costs2
Implementing speed safety cameras (automated speed enforcement) that use revenues to fund safety infrastructure	Reduces the prevalence of speeding behaviors given the certainty of punishment for offenders	−				Medium
Implementing red-light camera enforcement that uses revenues to improve safety	Reduces the prevalence of red-light-running given the certainty of punishment for offenders			−	−	Medium
Linking police with emergency medical service (EMS)/hospital data for persons injured in motor vehicle crashes	Provides a more accurate and comprehensive understanding of the harm induced by road trauma that may not be available within crash data	−	−	−		Medium
Forming a task force or community coalition of law enforcement, transportation, public health, members of the community, and other partners to investigate serious crashes (either before or after the crash report is complete) and report findings and proposed changes to the public	Strengthens the investigation of crash causes and provides contextual information that can be used to inform changes to policies and infrastructure	−	−	−		Low
Encouraging and facilitating public use of self-reporting (via mobile app or survey) to capture collisions and other events falling outside the scope of traditional crash reporting (e.g., near misses, pedestrian and bicyclist falls) outside of the crash data system	Proactively informs law enforcement and design and planning practitioners about concerning locations so additional enforcement or infrastructure improvements could be implemented before serious crashes occur	−	−	−		Low

Note: − = Not applicable.

¹ IRA = injury risk assessment, PCC = professional and community coordination, CD = crash diagnoses.

² Costs correspond to the total financial cost associated with a policy or practice, including labor, equipment, and infrastructure (Low ≤ $100k; Medium = $100k−$1 million; and High ≥ $1 million in total or per year).

For example, in step 1, if a safety team identifies and prioritizes addressing impaired driving, they might pursue requiring the installation of alcohol ignition interlocks for all drivers convicted of DUI given the importance of addressing the problem to community representatives and the availability of community resources to address impaired driving.

Then, in step 2, a safety team might conclude that an alcohol ignition interlock program aligns with the Safe System strategy to enforce road-user protective policies. They might also conclude that an alcohol ignition interlock program can reduce offending drivers’ and other road users’ exposure to serious crash risk, and the likelihood of serious crashes on the road network.

At this point, a team should reflect on whether a selected safety practice: (1) aligns with one or more Safe System strategies; (2) can significantly reduce the likelihood of users’ exposure to severe crash forces or enhance injury risk assessment, professional and community coordination, or crash diagnoses; and (3) is feasible given available resources to institute the practice. If the team concludes that all three criteria are satisfied, the practice should be considered for implementation, and the safety team could follow the steps outlined in Table 11. However, if one or more of these three criteria are not satisfied, teams are recommended to start over from step 1 until all three criteria are satisfied.

For illustrative purposes, a safety team looks to install alcohol ignition interlocks for all drivers convicted of DUI. Table 11 provides recommended steps to implement this safety practice along with elements to consider within each step.

Conclusion

The shift toward Safe System–aligned law enforcement practices is possible and necessary for the United States to realize zero deaths and serious injuries on the nation’s roadways. Law enforcement personnel collaborating with planners and road designers can proactively prevent serious crashes from reoccurring and can inform decisions about appropriate modifications to safety policy and infrastructure. This sort of collaboration is at the heart of the next chapter, which covers Safe System–aligned post-crash response strategies and practices.

Table 11. Law enforcement practice implementation steps and example elements.