A Guide to Applying the Safe System Approach to Transportation Planning, Design, and Operations (2025)
Chapter: Appendix A: Safe System Policy Practices
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Suggested Citation:
"Appendix A: Safe System Policy Practices." National Academies of Sciences, Engineering, and Medicine. 2025. A Guide to Applying the Safe System Approach to Transportation Planning, Design, and Operations. Washington, DC: The National Academies Press.
doi: 10.17226/29147.
APPENDIX A
Safe System Policy Practices
Appendix A provides data on how respondents appraised various Safe System policy practices. See Table A-1 for scores related to each practice’s feasibility and impact.
Interpretive categorization of Z-scores (Feasibility and Impact columns), with a mean of zero (0) and standard deviation (SD) of one (1).
| Categories | Z-scores |
|---|---|
| High | > 1 SD above mean |
| Moderate | < 1 and > 0 |
| Low | > −1 and < 0 |
| Very Low | < −1 SD below mean |
Note: SD = standard deviation round the mean score of zero (0).
Suggested Citation:
"Appendix A: Safe System Policy Practices." National Academies of Sciences, Engineering, and Medicine. 2025. A Guide to Applying the Safe System Approach to Transportation Planning, Design, and Operations. Washington, DC: The National Academies Press.
doi: 10.17226/29147.
Table A-1. Policy practice feasibility and impact scores (n = 85).
| Practice | Feasibility | Impact | Category |
|---|---|---|---|
| Installing leading pedestrian intervals with right-turn-on-red restrictions in areas with high pedestrian activity. | 1.078 | 0.385 | High Feasibility/Moderate Impact |
| Updating NHTSA’s New Car Assessment Program to include pedestrian detection and collision avoidance safety tests. | 0.604 | 0.403 | Moderate Feasibility/Moderate Impact |
| Requiring alcohol ignition interlocks installed for all drivers convicted of driving under the influence. | 0.501 | 0.293 | Moderate Feasibility/Moderate Impact |
| Developing policies requiring forward- and nearside-facing sensors on heavy vehicles to detect pedestrians and cyclists. | 0.337 | 0.324 | Moderate Feasibility/Moderate Impact |
| Setting posted speed limits based on harm minimization principles, road function, and severe crash types rather than an 85th percentile rule. | 0.290 | 0.097 | Moderate Feasibility/Moderate Impact |
| Instituting or enforcing a statewide primary enforcement seat-belt-use law. | 0.169 | 0.179 | Moderate Feasibility/Moderate Impact |
| Implementing speed safety cameras (automated speed enforcement) that use revenues to improve safety. | −0.259 | 0.459 | Low Feasibility/Moderate Impact |
| Instituting or enforcing a statewide universal motorcycle helmet law that would require all motorcyclists to wear U.S. DOT–compliant helmets, regardless of the rider’s age or experience. | −0.100 | 0.197 | Low Feasibility/Moderate Impact |
| Installing seat belt interlocks in vehicles. | −0.055 | 0.150 | Low Feasibility/Moderate Impact |
| Implementing red-light-camera enforcement that uses revenues to fund safety infrastructure. | −0.046 | 0.133 | Low Feasibility/Moderate Impact |
| Installing speed governors in all municipal fleet vehicles. | 0.592 | −0.712 | Moderate Feasibility/Low Impact |
| Extending graduated driver licensing requirements to include all novice drivers regardless of age. | 0.136 | −0.258 | Moderate Feasibility/Low Impact |
| Establishing a default speed limit of 20 mph or lower in every business or residential district. | −0.062 | −0.271 | Low Feasibility/Low Impact |
| Instituting immediate administrative license revocation or suspension for alcohol- and drug-impaired driving offenses. | −0.312 | −0.085 | Low Feasibility/Low Impact |
| Lowering the blood alcohol concentration limit for driving from 0.08 to 0.05. | −0.146 | −0.463 | Low Feasibility/Low Impact |
| Requiring location-based speed limiters in all commercial and private vehicles in areas with high pedestrian activity. | −0.796 | 0.080 | Low Feasibility/Moderate Impact |
| Instituting a driver license renewal program that requires passing an on-road driving test every 5–10 years. | −0.477 | −0.295 | Low Feasibility/Low Impact |
| Promoting the installation of technology in private automobiles that records drivers’ distraction, drowsiness, and other forms of incapacitation. | −0.788 | −0.133 | Low Feasibility/Low Impact |
| Establishing maximums in vehicle size (in terms of width, length, height, weight) permitted in areas with high pedestrian activity. | −0.666 | −0.486 | Low Feasibility/Low Impact |
Suggested Citation:
"Appendix A: Safe System Policy Practices." National Academies of Sciences, Engineering, and Medicine. 2025. A Guide to Applying the Safe System Approach to Transportation Planning, Design, and Operations. Washington, DC: The National Academies Press.
doi: 10.17226/29147.
Suggested Citation:
"Appendix A: Safe System Policy Practices." National Academies of Sciences, Engineering, and Medicine. 2025. A Guide to Applying the Safe System Approach to Transportation Planning, Design, and Operations. Washington, DC: The National Academies Press.
doi: 10.17226/29147.
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