ACTAR Vehicle Damage Analysis 4 — Questions and Answers
Question 1: In determining the principal direction of force (PDOF) for a collision, the analyst primarily examines:
- The color and type of paint transfer on each vehicle
- The orientation and direction of structural crush and deformation relative to the vehicle's centerline (Correct answer)
- The vehicle's pre-collision heading based on skid marks only
- The airbag deployment threshold recorded by the EDR
Correct answer: The orientation and direction of structural crush and deformation relative to the vehicle's centerline
PDOF is determined by analyzing the direction and orientation of structural damage and deformation, which reveals the resultant force vector applied to the vehicle.
Question 2: Which factor most significantly affects the accuracy of speed estimates derived from vehicle crush depth measurements?
- The vehicle's paint color and finish
- The accuracy and availability of vehicle-specific stiffness coefficients (A and B values) (Correct answer)
- The number of airbags that deployed
- The ambient temperature at the time of the collision
Correct answer: The accuracy and availability of vehicle-specific stiffness coefficients (A and B values)
Crush-based speed estimates depend critically on accurate stiffness coefficients; using coefficients from a dissimilar vehicle can introduce substantial error.
Question 3: A 'W' damage measurement pattern (W-crush profile) across the front of a vehicle most commonly indicates:
- A uniform, full-width barrier impact
- An offset impact where the vehicle struck a narrow object such as a pole or tree (Correct answer)
- A rear-end impact transferred through the powertrain
- A rollover with roof contact on a flat surface
Correct answer: An offset impact where the vehicle struck a narrow object such as a pole or tree
A W-shaped crush profile with deeper deformation at the center flanked by less-crushed areas is characteristic of a narrow-object impact such as a pole, where the object concentrated force centrally.
Question 4: Which document provides standardized nomenclature and codes for classifying vehicle collision damage for accident reconstruction purposes?
- The NHTSA Fatality Analysis Reporting System (FARS) manual
- The National Automotive Sampling System (NASS) general estimates manual and SAE J224 standard (Correct answer)
- The Insurance Institute for Highway Safety (IIHS) crash test protocol
- The Federal Motor Carrier Safety Regulations (FMCSR)
Correct answer: The National Automotive Sampling System (NASS) general estimates manual and SAE J224 standard
SAE J224 and the NASS coding manuals provide standardized terminology and coding schemes for documenting the type, extent, and location of vehicle collision damage.
Question 5: When measuring crush on a vehicle with a non-planar pre-collision surface (e.g., curved front fascia), the crush measurement should be taken:
- From the ground to the lowest damaged point
- Perpendicular to the original undamaged surface profile at each measurement location (Correct answer)
- Parallel to the vehicle's longitudinal centerline
- From the vehicle's centerline to the outermost point of deformation
Correct answer: Perpendicular to the original undamaged surface profile at each measurement location
Crush is measured perpendicular to the original undamaged surface so that the measurement accurately reflects the depth of deformation caused by the impact.
Question 6: Event data recorders (EDRs) can supplement vehicle damage analysis by providing:
- Real-time GPS tracking of the vehicle's route before the crash
- Pre-crash vehicle speed, brake application, and delta-V data from the collision event (Correct answer)
- Insurance policy information for the vehicle owner
- Tire tread depth measurements at the time of the crash
Correct answer: Pre-crash vehicle speed, brake application, and delta-V data from the collision event
EDRs record pre-crash parameters such as speed, throttle, and brake status, plus collision delta-V, which can be compared against crush-based estimates for validation.
Question 7: The 'damage width' used in CRASH energy calculations is defined as:
- The total width of the vehicle's front bumper
- The lateral extent of the damaged zone measured parallel to the struck surface (Correct answer)
- The distance from the vehicle centerline to the outermost undamaged panel
- The width of the opposing vehicle's striking surface
Correct answer: The lateral extent of the damaged zone measured parallel to the struck surface
Damage width (L) is measured along the surface of the struck vehicle, spanning the full lateral extent of the contact/damage zone.
ACTAR Vehicle Damage Analysis 4
In determining the principal direction of force (PDOF) for a collision, the analyst primarily examines: