The speed of the rollers should be controlled and should be slow. According to the NAPA SMA handbook QIS 122, the speed of a roller during rolling must not exceed 5 km/h. In one of the British guidelines, the speed of the rollers should normally be between 4 and 6 km/h (SEHAUC, 2009).
Rolling with vibration at a reduced speed improves the effectiveness of compaction. However, doing so may lead to crushing particles and squeezing mastic out on the surface of a layer. Therefore great caution should be exercised, and vibration should be turned off if need be. Rollers with a speed control option enable automatic control to disengage vibrations during braking and changing direction. It should be kept in mind that rollers with speed control require a longer braking distance and skillful control.
