ACTAR Evidence Collection 4 — Questions and Answers
Question 1: When documenting occupant kinematics using interior damage evidence, which feature of steering wheel deformation is MOST informative about driver contact forces?
- The color change in the steering wheel cover
- The direction and magnitude of rim offset from its original plane (Correct answer)
- The number of spokes on the wheel
- The distance from the wheel to the seat back
Correct answer: The direction and magnitude of rim offset from its original plane
Steering wheel rim deformation direction and magnitude indicates the vector and approximate force of the driver's chest or hand contact during the crash.
Question 2: A crash reconstructionist is examining a vehicle that impacted a guardrail. Which piece of evidence best establishes the vehicle's initial contact point on the guardrail?
- The location of the furthest debris from the guardrail
- The leading edge of paint transfer and gouging on the guardrail beam (Correct answer)
- The guardrail end terminal position
- The distance between guardrail posts
Correct answer: The leading edge of paint transfer and gouging on the guardrail beam
The leading edge of paint transfer and initial gouge marks on the guardrail surface identify where the vehicle first contacted the structure.
Question 3: Which type of witness evidence should be treated with the MOST caution when reconstructing vehicle speed?
- A professional driver who regularly operates on the same roadway
- A stationary pedestrian who briefly observed the vehicles (Correct answer)
- An adjacent vehicle driver traveling the same direction
- A traffic engineer who was measuring speeds in the area
Correct answer: A stationary pedestrian who briefly observed the vehicles
Stationary witnesses observing a brief event have limited ability to accurately estimate vehicle speed, as speed perception is highly unreliable for untrained observers.
Question 4: When collecting glass fracture evidence at a crash scene, the pattern of radial and concentric fractures can help determine:
- The type of glass manufacturer
- The direction and sequence of impact forces applied to the glass (Correct answer)
- The age of the vehicle's windshield
- The chemical composition of the glass
Correct answer: The direction and sequence of impact forces applied to the glass
Radial fractures propagate outward from the point of impact, and concentric fractures form around it; sequence analysis reveals whether multiple impacts occurred and in what order.
Question 5: A reconstructionist collects a soil sample from a vehicle's undercarriage following a crash that occurred in a rural area. This evidence is MOST useful for:
- Estimating the vehicle's fuel consumption
- Corroborating or refuting the alleged crash location (Correct answer)
- Determining the vehicle's weight at the time of impact
- Establishing the driver's identity
Correct answer: Corroborating or refuting the alleged crash location
Soil composition analysis can be compared to samples from the alleged crash site to confirm or dispute where the vehicle traveled before or during the incident.
Question 6: In a pedestrian fatality investigation, which evidence at the impact point is MOST important for establishing the pedestrian's position relative to the vehicle at first contact?
- Witness accounts of the pedestrian's clothing color
- The leading edge of blood and biological trace material on the roadway (Correct answer)
- The location of the pedestrian's belongings after the crash
- The position of the pedestrian's body after coming to rest
Correct answer: The leading edge of blood and biological trace material on the roadway
The leading edge of blood, tissue, or biological evidence on the roadway marks the first contact point between vehicle and pedestrian.
Question 7: When an ACTAR reconstructionist photographs tire marks using photogrammetry for later measurement, what calibration step is essential for accurate results?
- Photographing only during daylight hours
- Placing calibrated scale references (targets) within the photographic frame (Correct answer)
- Using a minimum of 50 megapixel resolution
- Photographing from a fixed height of exactly 6 feet
Correct answer: Placing calibrated scale references (targets) within the photographic frame
Calibrated scale targets with known dimensions provide the photogrammetry software with the scale reference needed to convert pixel measurements to real-world dimensions.
ACTAR Evidence Collection 4
When documenting occupant kinematics using interior damage evidence, which feature of steering wheel deformation is MOST informative about driver contact forces?