Problem Identification Identify current and potential road safety

Problem Identification Identify current and potential road safety problems using suitable scientific methods. 0 Module 4 -3

Major Topics High Risk Sites Comparable Sites with Promise (SWi. Ps) Crash Types Motives for Action 1 Module 4 -3

Identifying High Risk Sites Priority/Emphasis Areas • Political Will • Funding Sources • Data-Driven “High Risk” Sites 2 Module 4 -3

Ranking Using Crash Frequency 1 2 Site Observed Crash Frequency F 0 3 1 20. 5 2 16. 3 3 15. 5 4 9. 7 5 7. 5 6 5. 5 7 4. 7 8 1. 3 9 1. 0 10 0. 5 Module 4 -3

Ranking Using Crash Rates 4 1 2 3 Site Observed Crash Frequency Observed Crash Rate F 0 R 0 1 20. 5 3. 9 2 16. 3 5. 1 3 15. 5 7. 4 4 9. 7 8. 8 5 7. 5 5. 0 6 5. 5 2. 1 7 4. 7 2. 3 8 1. 3 7. 5 9 1. 0 10 0. 5 0. 7 Module 4 -3

Considering What is Normal for Comparable Sites 5 1 2 3 4 5 6 7 8 9 10 11 Site Observed Crash Frequency Observed Crash Rate Normal Crash Frequency Standard Deviation Normal Crash Rate Standard Deviation Difference in Frequencies Scaled Diff. in Rates Scaled Rate Diff. F 0 R 0 FN σF RN σR ΔF ΔF/σF ΔR ΔR/σR 1 20. 5 3. 9 26. 5 9. 4 5. 1 1. 8 -6. 0 -0. 6 -1. 2 -0. 7 2 16. 3 5. 1 16. 3 4. 8 5. 1 1. 5 +0. 0 3 15. 5 7. 4 9. 0 2. 5 4. 3 1. 2 +6. 5 +2. 6 +3. 1 +2. 6 4 9. 7 8. 8 7. 6 2. 1 6. 9 1. 9 +2. 1 +1. 0 +1. 9 +1. 0 5 7. 5 5. 0 3. 8 1. 4 2. 5 0. 9 +3. 7 +2. 6 +2. 5 +2. 8 6 5. 5 2. 1 12. 0 5. 5 4. 6 2. 1 -6. 5 -1. 2 -2. 5 +1. 2 7 4. 7 2. 3 3. 0 0. 6 1. 5 0. 3 +1. 7 +2. 8 +0. 8 +2. 7 8 1. 3 7. 5 0. 6 0. 2 3. 1 0. 9 +0. 7 +3. 5 +4. 4 +4. 9 9 1. 0 10. 0 0. 5 0. 2 5. 0 2. 1 +0. 5 +2. 5 +5. 0 +2. 4 10 0. 5 0. 7 3. 8 1. 7 5. 5 2. 4 -3. 3 -1. 9 -4. 8 -2. 0 Module 4 -3

SPFs for Problem Identification 1. 2 X XX X C 1. 0 Crashes per unit time 0. 6 0. 4 0. 2 X X D X X X X XA X B X XX XX 1, 000 2, 000 3, 000 4, 000 5, 000 6 SPF Safety 101 Annual Driving Miles Module 4 -3

Addressing Variability in Crashes Year-to-Year 7 1 2 3 4 5 6 7 8 9 10 11 Site Observed Crash Frequency Observed Crash Rate Normal Crash Frequency Standard Deviation Normal Crash Rate Standard Deviation Difference in Frequencies Scaled Diff. in Rates Scaled Rate Diff. F 0 R 0 FN σF RN σR ΔF ΔF/σF ΔR ΔR/σR 1 20. 5 3. 9 26. 5 9. 4 5. 1 1. 8 -6. 0 -0. 6 -1. 2 -0. 7 2 16. 3 5. 1 16. 3 4. 8 5. 1 1. 5 +0. 0 3 15. 5 7. 4 9. 0 2. 5 4. 3 1. 2 +6. 5 +2. 6 +3. 1 +2. 6 4 9. 7 8. 8 7. 6 2. 1 6. 9 1. 9 +2. 1 +1. 0 +1. 9 +1. 0 5 7. 5 5. 0 3. 8 1. 4 2. 5 0. 9 +3. 7 +2. 6 +2. 5 +2. 8 6 5. 5 2. 1 12. 0 5. 5 4. 6 2. 1 -6. 5 -1. 2 -2. 5 +1. 2 7 4. 7 2. 3 3. 0 0. 6 1. 5 0. 3 +1. 7 +2. 8 +0. 8 +2. 7 8 1. 3 7. 5 0. 6 0. 2 3. 1 0. 9 +0. 7 +3. 5 +4. 4 +4. 9 9 1. 0 10. 0 0. 5 0. 2 5. 0 2. 1 +0. 5 +2. 5 +5. 0 +2. 4 10 0. 5 0. 7 3. 8 1. 7 5. 5 2. 4 -3. 3 -1. 9 -4. 8 -2. 0 Module 4 -3

Crash Types Crash (contributing) Factors • Human • Roadway • Vehicle • Environmental Collision Type (manner of collision) • Run-off Road • Rear End • Head On • Sideswipe Same Direction 8 Module 4 -3

Motives for Action Economic Efficiency Professional and Institutional Responsibility (QC) Fairness/equity 9 Module 4 -3

Review High Risk Sites Comparable Sites with Promise (SWi. Ps) Crash Types Motives for Action 10 Module 4 -3

Exercise #6 High Risk Entities 11 Module 4 -3