CHP Accident Investigation 3 — Questions and Answers
Question 1: When investigating a collision involving a suspected DUI driver, when should field sobriety tests (FSTs) be administered?
- Before any collision documentation begins
- Only at the police station after booking
- After the scene is secure and immediate medical needs are addressed (Correct answer)
- Only if the driver verbally admits to drinking
Correct answer: After the scene is secure and immediate medical needs are addressed
FSTs should be conducted after scene safety is established and medical emergencies are handled, as injured subjects may appear impaired due to injury rather than intoxication.
Question 2: What does steering wheel deformation and airbag deployment indicate to an accident investigator?
- The exact time the collision occurred
- The direction and approximate severity of impact forces experienced by the driver (Correct answer)
- Whether the driver had a prior criminal record
- The insurance coverage of the vehicle owner
Correct answer: The direction and approximate severity of impact forces experienced by the driver
Airbag deployment thresholds and steering wheel deformation patterns indicate the direction and approximate force of impact sustained by the driver's compartment.
Question 3: In accident reconstruction, what does 'Delta-V' refer to?
- The difference in vehicle speeds before impact
- The change in velocity a vehicle experiences during a collision (Correct answer)
- The distance between vehicles at first point of contact
- The variation in road grades at the collision site
Correct answer: The change in velocity a vehicle experiences during a collision
Delta-V (ΔV) is the change in velocity experienced by a vehicle during impact and is a key measure of collision severity used in reconstruction analysis.
Question 4: What physical evidence suggests a tire blowout may have caused a crash, as opposed to driver error?
- Straight skid marks leading to the point of impact
- Witness statements about loud music in the vehicle
- Scattered tire tread fragments and an asymmetric yaw mark originating before the crash (Correct answer)
- Damage confined only to the rear of the vehicle
Correct answer: Scattered tire tread fragments and an asymmetric yaw mark originating before the crash
Tire tread separation and a vehicle beginning to yaw before any apparent driver input suggests a sudden blowout caused sudden loss of vehicle control.
Question 5: In pedestrian collision investigation, what is the significance of measuring the pedestrian's 'throw distance'?
- To determine if the pedestrian was trespassing
- To estimate the vehicle's speed at the moment of impact using projectile motion formulas (Correct answer)
- To identify the pedestrian's country of origin
- To verify the pedestrian was crossing legally
Correct answer: To estimate the vehicle's speed at the moment of impact using projectile motion formulas
Pedestrian throw distance can be used with physics formulas to calculate the vehicle's speed at impact when other physical evidence is limited.
Question 6: Seatbelt webbing evidence at a collision scene is significant because it can:
- Show whether the vehicle was stolen
- Indicate if a seatbelt was worn and the forces experienced by the occupant during impact (Correct answer)
- Prove the driver's blood alcohol content
- Identify the vehicle's registered owner
Correct answer: Indicate if a seatbelt was worn and the forces experienced by the occupant during impact
Seatbelt webbing stretch, locking patterns, and bruising on the occupant verify seatbelt use and indicate the direction and magnitude of crash forces.
Question 7: When documenting vehicle damage, which measurement is most useful for estimating crush depth to calculate impact speed?
- Height of the vehicle's roof from the ground
- Residual crush depth measured perpendicular to the damaged surface (Correct answer)
- Total length of the vehicle
- Width of the windshield
Correct answer: Residual crush depth measured perpendicular to the damaged surface
Residual crush depth, measured perpendicular to the pre-impact vehicle surface, is used in energy-based speed calculations during accident reconstruction.
CHP Accident Investigation 3
When investigating a collision involving a suspected DUI driver, when should field sobriety tests (FSTs) be administered?