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CE 552

CE 552. - Typical crash rates and distributions - Crashes that take the highest toll on human life. Rates …why?. To compare locations To decide if a location is at abnormal risk Rate per million entering vehicles:. In-class calculation. In-class calculation.

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CE 552

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  1. CE 552 - Typical crash rates and distributions - Crashes that take the highest toll on human life

  2. Rates …why? • To compare locations • To decide if a location is at abnormal risk • Rate per million entering vehicles: In-class calculation

  3. In-class calculation This should really be RHMVM, shouldn’t it?

  4. Expected value analysis • Use only to compare “similar” sites (geometry, control, volume) • Problem: crashes are non-neg. count data (normal distribution does not apply) In-class calculation

  5. Cluster analysis • E.g., if a site has one right-angle, two rear-end and 6 left-turn crashes, one might say the left-turn crashes represent a cluster • But … what if the # of left turns is very high … then, is 6 high? • Need exposure data • Must usually use good engineering judgment

  6. High Crash Location Methods • Frequency • Rate • Severity/Cost • Some combination • Iowa DOT uses .2F+.2R+.6C • Critical Rate Factor method • Empirical Bayes

  7. Critical Crash Rate Factor method Error: this should say Z, not S For derivation of equation and interpretation of terms, see link

  8. Next step: engineering study at sites

  9. Summarizing crash data Type Severity, e.g., KABCO, MAIS • Time Periods • Hour • Day • Month Contributing Circumstances Environmental Conditions a) light condition b) surface condition

  10. Typical crash rates Iowa data for risk by road type Oregon crash rates (compare to Iowa) Source: NCHRP Web Only Document 126 Guidelines for using NC crash rates Crash rate discussion

  11. Aussie rates – compare road types

  12. European crash rates by road type Low traffic flow roads – there are significant differences in fatal and serious accident rate between roads with less than 10,000 Average Annual Daily Traffic (AADT), roads with 10,000 to 20,000 AADT, and roads with more than 20,000 AADT. (The ratio of these differences is about 2.3:1.8:1); Note: to convert /bvkm to /HMVM, multiply by ~6 (Iowa K+A+B crash rate per HMVM in ~60, much lower than the numbers presented above for Europe if you multiply them by 6) http://www.eurorap.org/library/pdfs/roaddesignfactors.pdf

  13. Kentucky Intersection Crash Rates http://www.ktc.uky.edu/Reports/KTC_03_21_SPR258_03_2I.pdf

  14. Massachusetts Intersection Crash Rates

  15. From Oregon Study … http://www.oregon.gov/ODOT/HWY/TRAFFIC-ROADWAY/docs/pdf/safety_of_4-leg_vs_T.pdf

  16. http://www.oregon.gov/ODOT/HWY/TRAFFIC-ROADWAY/docs/pdf/safety_of_4-leg_vs_T.pdfhttp://www.oregon.gov/ODOT/HWY/TRAFFIC-ROADWAY/docs/pdf/safety_of_4-leg_vs_T.pdf

  17. http://www.oregon.gov/ODOT/HWY/TRAFFIC-ROADWAY/docs/pdf/safety_of_4-leg_vs_T.pdfhttp://www.oregon.gov/ODOT/HWY/TRAFFIC-ROADWAY/docs/pdf/safety_of_4-leg_vs_T.pdf

  18. http://www.oregon.gov/ODOT/HWY/TRAFFIC-ROADWAY/docs/pdf/safety_of_4-leg_vs_T.pdfhttp://www.oregon.gov/ODOT/HWY/TRAFFIC-ROADWAY/docs/pdf/safety_of_4-leg_vs_T.pdf

  19. Crashes that take the highest toll on human life • Head-ons, Intersections, ROR, VRU • Show iRAP video http://www.eurorap.org/library/pdfs/roaddesignfactors.pdf

  20. Head-on collisions • head-on crash. • Fatal Head On Accident Six Killed On US12 Near Morton WA • Truck crossing median – 7 fatals video http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_500v20.pdf

  21. Intersections (junctions) See: UMN captured crashes http://onlinepubs.trb.org/Onlinepubs/nchrp/nchrp_rpt_500v5.pdf

  22. Manner of collision

  23. Run-off the road (ROR) http://www.t2.unh.edu/nltapa/Pubs/fhwa's_roadway_departure_program.pdf http://www.t2.unh.edu/nltapa/Pubs/PLD-1.pdf

  24. http://onlinepubs.trb.org/Onlinepubs/nchrp/nchrp_rpt_500v6.pdfhttp://onlinepubs.trb.org/Onlinepubs/nchrp/nchrp_rpt_500v6.pdf http://www.t2.unh.edu/nltapa/Pubs/fhwa's_roadway_departure_program.pdf

  25. Vulnerable Road users Motorcycles, bikes, pedestrians • Bicyclists and Other Cyclists (DOT-HS-810-986) • http://onlinepubs.trb.org/Onlinepubs/nchrp/nchrp_rpt_500v10.pdf • http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_500v22.pdf

  26. Children

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