1.1 ,This test method covers the measurement of the frictional properties of winter-contaminated pavement surfaces using an averaging-type spot measuring decelerometer. If a data phone is used, it should meet all the requirements where the word decelerometer is used in this standard. The method produces a reading that is proportional to the deceleration sustained by a test vehicle fitted with pneumatic rubber tires braking with all wheels locked. A friction index for a section of winter-contaminated pavement is determined from the average of several deceleration measurements recorded over the section of winter-contaminated pavement.