4.11 Accident investigation

Front

What is the drag factor in accident investigation?

Back

The drag factor is a coefficient that represents the friction between the tires and the road surface, used to calculate stopping distances and vehicle speeds during an accident investigation.

Front

How do you calculate the average skid distance from multiple skid marks?

Back

To calculate the average skid distance, add the lengths of all skid marks and divide by the number of skid marks.

Front

What is the significance of brake efficiency in accident reconstruction?

Back

Brake efficiency indicates how effectively a vehicle can stop. It is expressed as a percentage and affects calculations of stopping distances and speeds.

Front

What is the formula to determine the minimum speed of a vehicle based on yaw marks?

Back

Minimum speed (mph) = √(radius of yaw mark (ft) × drag factor) × 0.6.

Front

What is a yaw mark and what does it indicate in an accident investigation?

Back

A yaw mark is a curved skid mark left by a vehicle that is sliding sideways, indicating loss of traction and the vehicle's path during a turn.

Front

What is the purpose of measuring skid marks at an accident scene?

Back

Measuring skid marks helps determine the speed of the vehicle at the time of braking and can provide insights into the dynamics of the accident.

Front

How does road surface type affect the drag factor?

Back

Different road surfaces (e.g., asphalt, concrete, gravel) have varying levels of friction, which affects the drag factor and consequently the vehicle's stopping distance.

Front

What is the middle ordinate in relation to yaw marks?

Back

The middle ordinate is the perpendicular distance from the midpoint of a chord to the arc of the curve, used to calculate the radius of the curve.

Front

What is the relationship between speed and skid distance?

Back

Generally, the greater the speed of a vehicle, the longer the skid distance will be, due to increased momentum and the time required to stop.

Front

What factors can influence the length of skid marks?

Back

Factors include vehicle speed, road surface conditions, tire condition, brake efficiency, and the weight of the vehicle.