Collision Analysis & Reconstruction 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 Collision Analysis & Reconstruction flashcards as text
In reconstruction of a run-off-road rollover, the 'trip mechanism' most commonly involves which of the following?
Answer: The tire contacting a curb, soft soil, or other tripping element that induces roll
The most common rollover trip mechanism is the tire encountering a curb, soft shoulder, or similar tripping feature that redirects the vehicle's lower structure while inertia continues it laterally.
A reconstructionist determines two vehicles' post-impact velocities using momentum analysis. What additional step is needed to find their pre-impact speeds?
Answer: Add back each vehicle's energy loss during the collision using the coefficient of restitution or crush energy
Pre-impact speeds require accounting for energy dissipated during the collision, which is done using crush energy or the coefficient of restitution applied to post-impact velocities.
Which scene documentation method is best suited for capturing three-dimensional spatial data of a large crash scene rapidly and accurately?
Answer: 3D laser scanning (LiDAR)
3D laser scanning (LiDAR) captures millions of spatial data points rapidly, providing a highly accurate, georeferenced three-dimensional record of the entire crash scene.
When analyzing a pedestrian throw distance to estimate vehicle speed, which formula is most commonly referenced?
Answer: Searle's formula using pedestrian throw distance and drag factor
Searle's formula (and related variants) correlates vehicle pre-impact speed to the pedestrian's throw distance and the friction between pedestrian and road surface.
An adjustable drag sled test on the crash scene pavement returns values of 0.68, 0.71, and 0.73. What value should the reconstructionist use for skid-speed calculations if conservatism favoring the driver is required?
Answer: The lowest value, 0.68
Using the lowest drag factor value is conservative in the driver's favor because it yields the lowest calculated speed for a given skid distance.
What does 'delta-V' represent in the context of a vehicle collision?
Answer: The change in velocity experienced by a vehicle during the collision
Delta-V is the vector change in a vehicle's velocity from just before to just after the collision, representing the severity of the crash experienced by that vehicle.
In a reconstruction involving a vehicle that vaulted off a roadway embankment, which projectile motion parameter must be measured from the scene to calculate launch speed?
Answer: Horizontal range and vertical drop of the vault trajectory
Horizontal range and vertical drop from the launch point to the landing point are the essential measurements for applying projectile motion equations to calculate launch speed.