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
When documenting skid marks at a crash scene, what is the recommended method for measuring curved skid marks?
Answer: Use a tape along the arc of the mark and record the chord and middle ordinate
Curved skid marks are measured using the arc length along the tire mark, with the chord and middle ordinate recorded to allow mathematical reconstruction of the radius.
Which type of coordinate system is most appropriate for documenting a large-scale crash scene covering multiple city blocks?
Answer: GPS-based coordinate system tied to a geodetic datum
A GPS-based system tied to a geodetic datum provides scalable, reproducible coordinates suitable for large scenes and integration with GIS or CAD software.
What is the primary purpose of establishing a baseline in crash scene survey?
Answer: To provide a reference line from which all other measurements are taken
A baseline is a known reference line, typically along the roadway edge or centerline, from which perpendicular and along-baseline measurements are made.
In aerial or drone photography of a crash scene, what minimum overlap between adjacent photos is recommended to ensure complete photogrammetric coverage?
Answer: 60–80%
A 60–80% overlap between adjacent images ensures that common points appear in multiple photos, enabling accurate 3D reconstruction through photogrammetry.
When photographing gouge marks in pavement at a crash scene, which technique best captures depth and three-dimensional character?
Answer: Low-angle side lighting (raking light) with a scale marker
Low-angle raking light creates shadows that reveal depth and texture of gouge marks, while a scale marker allows size determination from the photograph.
Which statement correctly describes the difference between 'total station' and 'GPS RTK' for crash scene documentation?
Answer: Total stations provide millimeter accuracy without satellite dependency; GPS RTK requires clear sky view and satellite lock
Total stations achieve sub-millimeter accuracy using optical angle and distance measurement without needing satellite signals, whereas GPS RTK requires open sky and reliable satellite lock.
What information should be recorded in the field notes when documenting tire mark evidence at a crash scene?
Answer: Location, length, width, direction, surface condition, and relative position to fixed features
Comprehensive tire mark documentation requires recording location, dimensions, orientation, surface condition, and relationship to fixed scene features for accurate reconstruction.