f. Backing Road Roller. Do not accelerate suddenly. Watch for stones, metal scrap, and other sharp matter which
may damage the rolls. Avoid sharp and fast turns. Do not jerk or brake suddenly.
g. Sprinkler. The sprinkler system is controlled by the dual sprinkler pedals (14, fig. 10). The outside pedal operates
the steering roll sprinkler valve. The inside pedal operates the compression roll sprinkler valve. Push the pedal down to
open sprinkler valve. Use the sprinkler system only when needed. When not in use, raise the sprinkler mats to prevent
unnecessary wear.
31. Operating on Bituminous-Macadam Pavements
a. Foundation Course. After the foundation course of crushed stone or gravel with a depth of 6 to 8 inches is laid
evenly over the subgrade, the rolling must begin from the sides and progress toward the center. The roller must be kept
moving parallel to the center line of the road. In the case of a superelevated road the rolling must be started at the low
side of the curve and progress to the high side.
b. Wearing Course. Roll the wearing course in the same manner as described in a above. Continue to roll the
wearing course stone until it is well keyed and suitable for the application of bituminous binder.
c. Key or Filler Stone. After the key or filler stone is evenly spread over the bituminous binder, the stone must be
rolled as described in a above until the stone is bonded with the penetrated wearing course and makes tight and compact
surface.
d. Cover Stone. The cover stone is rolled in the same manner as the key or filler stone (see c above).
32. Operating on Bituminous-Concrete and Sheet-Asphalt Pavements
a. General. The rolling methods described in b and c below will apply to the following types of bituminous-concrete
and sheet-asphalt pavement constructions: Topeka (fine-graded bituminous concrete), Warrenite-Bitulithic (coarse-
graded bituminous concrete), Amiesite, Tarvialithic, Tarmac, Slagmac, Westphalt, Colprovia, Macasphalt, and Precote.
b. Binder Course. The binder course mixture must be distributed in place by means of hot shovels and spread with
hot rakes in a loose layer of uniform density and depth that when rolled will compact to the desired thickness. The binder
course mixture must be rolled while hot. The rolling should start at the sides and proceed longitudinally toward the center
by overlapping on successive trips by about one-half of the width of compression roll. After this rolling is finished, the
pavement should be rolled diagonally, in two directions, so that the
29
