ACTAR Scene Documentation 5

Question 1

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?

Accepted Answer

It identifies where the primary collision occurred; best evidence is gouge marks, scrape marks, and fluid deposits in the roadway

Answer

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.

Question 2

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?

Accepted Answer

Focal length and sensor size (or equivalent 35mm focal length)

Answer

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.

Question 3

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)?

Accepted 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

Answer

Documenting under both conditions shows investigators how the scene appeared during evidence collection and recreates the visibility conditions experienced by the involved drivers.

Question 4

What is the purpose of a 'scale bar' or 'scale reference' placed in a photograph of crash scene evidence?

Accepted Answer

To allow the physical size of objects in the photograph to be determined accurately

Answer

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.

Question 5

When a roadway has been resurfaced after a crash, how can a reconstructionist document the original pavement condition for the crash date?

Accepted Answer

Obtain pre-crash maintenance records, road inspection reports, prior crash reports, and any photographs taken near the crash date

Answer

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.

(ACTAR) Accreditation Commission for Traffic Accident Reconstructionist Practice Test

(ACTAR) Accreditation Commission for Traffic Accident Reconstructionist Practice Test

ACTAR Scene Documentation 5