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.
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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).

Page 74
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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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
Page 73
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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Page 73
Page 74
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.
Save
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