ACTAR Scene Documentation 2

Question 1

When documenting skid marks at a crash scene, what is the recommended method for measuring curved skid marks?

Accepted Answer

Use a tape along the arc of the mark and record the chord and middle ordinate

Answer

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.

Question 2

Which type of coordinate system is most appropriate for documenting a large-scale crash scene covering multiple city blocks?

Accepted Answer

GPS-based coordinate system tied to a geodetic datum

Answer

A GPS-based system tied to a geodetic datum provides scalable, reproducible coordinates suitable for large scenes and integration with GIS or CAD software.

Question 3

What is the primary purpose of establishing a baseline in crash scene survey?

Accepted Answer

To provide a reference line from which all other measurements are taken

Answer

A baseline is a known reference line, typically along the roadway edge or centerline, from which perpendicular and along-baseline measurements are made.

Question 4

In aerial or drone photography of a crash scene, what minimum overlap between adjacent photos is recommended to ensure complete photogrammetric coverage?

Accepted Answer

60–80%

Answer

A 60–80% overlap between adjacent images ensures that common points appear in multiple photos, enabling accurate 3D reconstruction through photogrammetry.

Question 5

When photographing gouge marks in pavement at a crash scene, which technique best captures depth and three-dimensional character?

Accepted Answer

Low-angle side lighting (raking light) with a scale marker

Answer

Low-angle raking light creates shadows that reveal depth and texture of gouge marks, while a scale marker allows size determination from the photograph.

(ACTAR) Accreditation Commission for Traffic Accident Reconstructionist Practice Test

(ACTAR) Accreditation Commission for Traffic Accident Reconstructionist Practice Test

ACTAR Scene Documentation 2