Yaws

Another element experts often analyze for speed determination is a yaw mark*. Yaws are a type of skid mark, but can generally be defined as “a physical mark on the roadway caused by the rotating tires of a vehicle slipping in a direction parallel to the axle of the wheel during a maximum rate change of direction," according to Joseph Badger. These marks are often left behind when a driver turns quickly or changes direction to avoid an object or another vehicle in the road (see Figure 2). Yaws are always curved, “initiated by steering input,” and are also parallel to a vehicle’s axis."

Figure 1. A yaw mark on pavement.
(Source: Car and Driver, 2002)

Figure 2. Yaw marks left behind after a “high speed spin.” This photo was taken after the accident of Bruce McLaren, who was driving at 180 mph before he crashed and killed himself in 1970.
(Source: Car and Driver, 2002)

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