Scene Documentation Flashcards
7 cards from real ACTAR practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Scene Documentation flashcards as text
What is the significance of documenting the 'area of impact' (AOI) at a crash scene, and which type of evidence is most diagnostic for locating it?
Answer: It identifies where the primary collision occurred; best evidence is gouge marks, scrape marks, and fluid deposits in the roadway
The AOI is where the collision force was exchanged, and physical evidence such as gouges, scrapes, and fluid drops left by undercarriage contact most precisely locates this zone.
When using Structure from Motion (SfM) photogrammetry software to create a 3D model, which camera setting is critical to record in the field to improve model accuracy?
Answer: Focal length and sensor size (or equivalent 35mm focal length)
SfM software uses the camera's focal length and sensor dimensions to model lens geometry; inaccurate or unknown values degrade the accuracy of the reconstructed 3D model.
In documenting a nighttime crash scene with artificial lighting, why is it important to photograph the scene under both artificial lighting and in the dark (with only headlight simulation)?
Answer: To show how the scene appeared under investigation conditions and to show how a driver would have seen it at the time of the crash
Documenting under both conditions shows investigators how the scene appeared during evidence collection and recreates the visibility conditions experienced by the involved drivers.
What is the purpose of a 'scale bar' or 'scale reference' placed in a photograph of crash scene evidence?
Answer: To allow the physical size of objects in the photograph to be determined accurately
A scale bar placed in the same plane as the subject provides a known reference dimension so that the actual size of documented features can be calculated from the photograph.
When a roadway has been resurfaced after a crash, how can a reconstructionist document the original pavement condition for the crash date?
Answer: Obtain pre-crash maintenance records, road inspection reports, prior crash reports, and any photographs taken near the crash date
Maintenance logs, inspection records, prior crash reports, and time-stamped photographs from near the crash date can establish the original pavement condition when the surface has since been altered.
Which field measurement error most commonly causes significant positional inaccuracies when using the two-reference-point (triangulation) method with a measuring tape?
Answer: Tape sag due to not keeping the tape horizontal and taut during long measurements
A sagging, non-horizontal tape reads a longer arc length than the true horizontal distance, introducing systematic error that compounds over longer measurements.
What standard practice should be followed when the crash scene crosses jurisdictional boundaries (e.g., county or state lines)?
Answer: Coordinate with all relevant agencies, note the jurisdictional boundary in the documentation, and ensure all areas are fully documented
Complete documentation requires coordinating across jurisdictions, clearly noting boundary locations, and ensuring no evidence area is omitted due to jurisdictional gaps.