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Collision Investigation Checklist and Momentum Analysis

This checklist provides an investigation guideline for determining the point of impact and analyzing momentum in different types of collisions. It includes match analysis of gouge marks, scrape marks, debris, scuff marks, tire marks, fluid dumping, and post-impact motion. The checklist also covers in-line momentum analysis and sensitivity analysis to determine post-impact distances, speeds, and angles.

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Collision Investigation Checklist and Momentum Analysis

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  1. In-line Collisions

  2. HEAD-ON REAR-END

  3. Investigation checklist: Determining the POI is critical.

  4. POI Location in Crossing the Center Line Case

  5. gouge caused by steering linkage

  6. gouge caused by drive shaft

  7. Match the gouge to thelocation on the vehicle. gouge caused by drive shaft

  8. Match the gouge to thelocation on the vehicle.

  9. Match the gouge to thelocation on the vehicle.

  10. Impact gouge marks should be matched to one of the vehicles • Scrape marks or scratches on the road • Debris • Impact scuff marks • Tire marks to FRP • Fluid “dumping”, run-off, and pooling • Post-impact motion consistent with theory

  11. Speed Analysis

  12. momentum = weight x velocity

  13. momentum = 36,000 lb ft/sec

  14. momentum = 36,000 lb ft/sec ?

  15. momentum = - 36,000 lb ft/sec

  16. IN-LINE MOMENTUM 1 1 2 2 NO APPROACH OR EXIT ANGLE GREATER THAN 5O

  17. IN-LINE MOMENTUM V1 V3 V2 V4 1 1 2 2 total momentum before = total momentum after W1 V1 + W2 V2 = W1 V3 + W2 V4

  18. CAVEAT : When W2 >> W1, momentum should be used with caution to determine speed for smaller MV V1 V2

  19. 3056 lbs 71,600 lbs

  20. 3056 lbs 71,600 lbs V2 = 42 mph V1 post-impact = 1.4 mph

  21. 3056 lbs 71,600 lbs V2 = 54 mph V1 post-impact = 1.9 mph

  22. What are the defenses ? Medical issue Mechanical failure or defect Evidence incomplete, not matched to vehicle POI incorrect Incorrect defense reconstruction Sight restrictions Passenger caused collision

  23. Intersection Collisions

  24. V3 V4 V1 V2

  25. momentum = weight x velocity

  26. Momentum = weight x velocity momentum is a “vector”: quantity direction 3,000lbs 30 mph P = 90,000 lb mph

  27. 360o momentum : V1 V2

  28. 90O Y - direction 0O 180O X - direction 270O

  29. A1 V1 A2 V2

  30. Y - direction A1 V1 X - direction A1 V1

  31. A2 V2 Y - direction X - direction A2 V2

  32. V3 V4 V1 V2

  33. A3 Y - direction V3 X - direction

  34. Y - direction A4 V4 X - direction

  35. V3 A3 V4 A4 A1 V1 A2 V2

  36. V3,A3,W3 V4A4,W4 V1, A1, W1 V2,A2,W2

  37. Impact gouges post-impact scrape

  38. The variables : Weights W1 W2 W3 W4 Post-impact speeds V3 V4 Approach angles A1 A2 Exit angles A3 A4 sensitivity analysis should be done in every case.

  39. Momentum analysis: post-impact distances post-impact drag factors post-impact speeds + exit angles + approach angles approach speeds

  40. V3 V4 V1 V2

  41. V3 V4 V1 = TOTAL MOMENTUM BEFORE TOTAL MOMENTUM AFTER V2

  42. V2 = + V1= + -

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