What is a primary focus when analyzing vehicle speed from skid marks?

When analyzing vehicle speed from skid marks, the primary focus is on the length and depth of the skid marks. This is because the length of the skid marks can provide valuable insight into how fast a vehicle was traveling before it began to skid. The greater the length of the skid marks, the higher the speed of the vehicle at the time the brakes were applied, assuming other factors such as the road surface and the condition of the tires are constant.

The depth of the skid marks can also indicate the coefficient of friction between the tires and the roadway, which is crucial in accurately calculating the speed. Together, these measurements allow investigators to apply formulas that take into account the dynamics of the skid, providing a reliable estimate of the vehicle's speed at the time of braking.

Factors such as the type of pavement and the condition of the tires may influence the overall results but do not directly determine speed as the length and depth of the skid marks do. The distance from the impact point may help establish context for the crash but is not typically used to calculate vehicle speed directly from skid marks.