ACTAR Collision Analysis & Reconstruction 3

Question 1

A reconstructionist uses the 'CRASH3' program or similar stiffness-based model. What does the stiffness coefficient 'B' represent?

Accepted Answer

The rate of force increase per unit of additional crush depth

Answer

The stiffness coefficient B represents the slope of the force-crush relationship — how much additional force is required per additional unit of crush.

Question 2

In a rollover reconstruction, which energy source is analyzed to estimate minimum vault speed?

Accepted Answer

Kinetic energy at the initiation point

Answer

The kinetic energy at roll initiation is analyzed, often using vault distance and height to back-calculate minimum pre-rollover speed.

Question 3

What does 'PDOF' stand for in the context of collision reconstruction?

Accepted Answer

Principal Direction of Force

Answer

PDOF — Principal Direction of Force — describes the resultant direction of the impact force applied to the vehicle.

Question 4

When analyzing a head-on collision between two vehicles of very different masses, which vehicle typically experiences the greater velocity change (delta-V)?

Accepted Answer

The lighter vehicle

Answer

By Newton's third law, the impulse is equal and opposite, so the lighter vehicle undergoes a greater velocity change (delta-V) because delta-V = impulse / mass.

Question 5

In the context of roadway evidence, what information do 'gouge marks' primarily provide to reconstructionists?

Accepted Answer

Point of maximum engagement or the area of contact between vehicles

Answer

Gouge marks are created when hard vehicle components contact the road surface and typically indicate the area of maximum engagement or point of impact.

(ACTAR) Accreditation Commission for Traffic Accident Reconstructionist Practice Test

(ACTAR) Accreditation Commission for Traffic Accident Reconstructionist Practice Test

ACTAR Collision Analysis & Reconstruction 3