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. This should really be RHMVM, shouldn’t it?

7. 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

8. 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

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

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

14. Next step: engineering study at sites

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

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

19. Aussie rates – compare road types

24. http://www.eurorap.org/library/pdfs/roaddesignfactors.pdf 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) 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); European crash rates by road type

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

27. Massachusetts Intersection Crash Rates

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

32. 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

33. Head-on collisions head-on crash. 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

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

36. Manner of collision

37. 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

38. http://onlinepubs.trb.org/Onlinep ubs/nchrp/nchrp_rpt_500v6.pdf http://www.t2.unh.edu/nltapa/Pubs/fhwa's _roadway_departure_program.pdf

40. 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_500v10.pdf http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_500v22.pdf

41. Children